VBQ and trail

[News Man]

Any readers of VBQ here who have seen the most recent issue. It has a section devoted to trail and it's various effects on stability at low, medium and high speed as well as cornering at low, medium and high speed. If I am reading it right, it would appear that bikes with very low trail i.e 30-42mm beat all comers in every category but stability at high speed. High trail bikes 62 or more are a close second and bikes in between a distant third.

Aren't most bikes, these days, designed with 60mm or so of trail? I think you would be hard pressed to find many low trail offerings, yet apparently they ride and handle quite well. What am I missing??

[dauwhe]

Any readers of VBQ here who have seen the most recent issue. It has a section devoted to trail and it's various effects on stability at low, medium and high speed as well as cornering at low, medium and high speed. If I am reading it right, it would appear that bikes with very low trail i.e 30-42mm beat all comers in every category but stability at high speed. High trail bikes 62 or more are a close second and bikes in between a distant third.

Aren't most bikes, these days, designed with 60mm or so of trail? I think you would be hard pressed to find many low trail offerings, yet apparently they ride and handle quite well. What am I missing??

This is a controversial topic, and Mr. Heine's views are probably not shared by a majority of bicycle designers. My impression is that for a low trail design to work, the bike probably needs a handlebar bag (as in the French randonneuring bikes) and relatively wide, lower-pressure tires.

This of course is based only on my reading lots of these articles. I have no personal experience riding low-trail bikes. I'll have to buy a Kogswell P/R!

Dave Cramer
VBQ fan club!

[News Man]

I have a Weigle Randonneur of recent vintage and I am unaware of the specifics of the geometry. I do know that I love the way it rides and according to VBQ the trail numbers are 42 give or take. The bike is equipped with 28's and no handlebar bag. What I notice most about the way this bike handles is that it is very easy to adjust your line while cornering at any speed. Much easier than my race bikes.

[e-RICHIE]

i thought the gist of their conclusions was based
on using the wheel sizes they like to use as well
as having baggage on the h'bar rack. were this
the case, then, yes - it makes sense. i didn't think
they were making sweeping statements about all
trail numbers. also - keep in mind that trail is made
up of two components, and the resultant trail number
may yield a completely different result on a frame
with different front centers.

[News Man]

i thought the gist of their conclusions was based
on using the wheel sizes they like to use as well
as having baggage on the h'bar rack. were this
the case, then, yes - it makes sense. i didn't think
they were making sweeping statements about all
trail numbers. also

As I read it, the conclusions were without front bags. Certainly much mention was made about them but I seem to recal there was a separate section that detailed the effects of front and rear bags. Front bags, in general, increased the stability on low trail bikes.


keep in mind that trail is made
up of two components, and the resultant trail number
may yield a completely different result on a frame
with different front centers.

This is interesting, I don't understand it but somehow I feel it is important. Can you provide a reference?

[e-RICHIE]

This is interesting, I don't understand it but somehow I feel it is important. Can you provide a reference?

if two frames have the same trail measurement and the
front centers differ by a cm or two, will the magazine
results hold?

if the two frames have the same trail measurement
and they result from differing head angle/rakes, will
the magazine results hold?

[News Man]

if two frames have the same trail measurement and the
front centers differ by a cm or two, will the magazine
results hold?

if the two frames have the same trail measurement
and they result from differing head angle/rakes, will
the magazine results hold?

Good questions. As I recall these results were simply their combined experience with all bikes thus reviewed by VBQ. I have only seen the reviews (and therefore geometries of) the Weigle and Van Cleve.

[e-RICHIE]

Good questions. As I recall these results were simply their combined experience with all bikes thus reviewed by VBQ. I have only seen the reviews (and therefore geometries of) the Weigle and Van Cleve.

a bicycle's behavior is the result of all of its design
elements combined as a unit, as well as by the rider
mass placed above and between the two wheels.
isolating a single measurement to draw conclusions
often overlooks the many others that are part of the
greater whole. the swiss new wave describe this as
gestalt-itis.


ps
btw unless my reading skills are fecked, the article
was about bicycles using 650B wheel sizes atmo.

[goonster]

keep in mind that trail is made
up of two components, and the resultant trail number
may yield a completely different result on a frame
with different front centers.

Those two components are head tube angle and front center, correct?

I'm going to have to go back through all the articles and figure out what exactly Jan means when he talks about "pneumatic trail". (I think he means "effective" trail with tires on the wheels, since trail can change with tire size)

Anyway, my impression from the articles was that low trail may result in stable handling at some speeds, but is really only stable at all speeds with a proper french-style (i.e. center of gravity close to the fork crown) handlebar bag.

I hope to order up just such a bike soonish. :beer:

[e-RICHIE]

Those two components are head tube angle and front center, correct?
no. head angle and fork blade offset.

...but is really only stable at all speeds with a proper french-style (i.e. center of gravity close to the fork crown) handlebar bag.

I hope to order up just such a bike soonish. :beer:


gestalt in french is configuration.

[jerk]

if two frames have the same trail measurement and the
front centers differ by a cm or two, will the magazine
results hold?

if the two frames have the same trail measurement
and they result from differing head angle/rakes, will
the magazine results hold?


no.

no.

oh, it was one of those rhetorical questions sorry.

jerk

[e-RICHIE]

no.

no.

oh, it was one of those rhetorical questions sorry.

jerk

have you ever completed paris brest hilton?

[goonster]

gestalt in french is configuration.

Surely this is a magnificent joke, which I don't understand.


if two frames have the same trail measurement and the
front centers differ by a cm or two, will the magazine
results hold?

if the two frames have the same trail measurement
and they result from differing head angle/rakes, will
the magazine results hold?

Do you have reason to believe they wouldn't?

I'm asking sincerely. I fully understand that the bike with rider must be considered as a whole, but if all other factors remain constant, and if one could modify the steering angle and front center, while maintaining constant trail, do you think the "handling", i.e. steering response, would change?

(If changing the front center involved changing the wheelbase, I guess it would.)

Yes: the article about the effect of trail on handling was written based on testing a 650b prototype Kogwell with different forks.

[jerk]

have you ever completed paris brest hilton?


yeah, she stole the jerk's line in the end though......fortunatly it was on a hooker's ***.

jerk

[e-RICHIE]

Surely this is a magnificent joke, which I don't understand.
apologies.
see above post.
i am a firm believer that it's a sum total thing
and that one detail cannot be taken out of context.
hence, my daily use of the term gestalt.



Do you have reason to believe they wouldn't?

I'm asking sincerely. I fully understand that the bike with rider must be considered as a whole, but if all other factors remain constant, and if one could modify the steering angle and front center, while maintaining constant trail, do you think the "handling", i.e. steering response, would change?

(If changing the front center involved changing the wheelbase, I guess it would.)

changing the front center is changing the wheelbase.
it's all connected.
if you re-orient the head angle and fork offset to
yield the same trail as you had before you touched
anything, the result would be that the front center
would be altered and so would the "space" between
the saddle and the h'bar assembly.

[goonster]

i am a firm believer that it's a sum total thing
and that one detail cannot be taken out of context.
hence, my daily use of the term gestalt.


I agree with you, and it is a good word, but I was confused because it's not French, which led me to suspect a deliberate joke. ;)

[e-RICHIE]

I agree with you, and it is a good word, but I was confused because it's not French, which led me to suspect a deliberate joke. ;)


well here's a tip...
you mentioned that your new mount was gonna be
one with a with a proper french-style, so - me, with
a compulsive need to use gestalt in daily conversation,
looked up the word on babelfish and realized that it
translated into configuration. i am doing all this
while reaming the tops of eight fork races.

[palincss]

Here's a link to a PDF of the test in question:
http://kogswell.com/testPR.pdf and here's a link to a page that discusses it and
includes a photo of the merry band of testers: http://kogswell.com/comparison.html

As you will see, the bikes indeed were tested with loads, some in handlebar bags, some not.

[News Man]

ps
btw unless my reading skills are fecked, the article
was about bicycles using 650B wheel sizes atmo.

No you are referring to the preceding article. You will note that the last article on trail is not specific to 650B. The ranges for what is low, medium and high trail are different for 650B and 700c. The last table in the publications is the one that I am refering to.

However you define Gestalt, it should include the Weigle. I remain ignorant of the exact geometry (as Peter really would prefer not to say), but the bike is sublime!

[e-RICHIE]

No you are referring to the preceding article. You will note that the last article on trail is not specific to 650B. The ranges for what is low, medium and high trail are different for 650B and 700c. The last table in the publications is the one that I am refering to.


my copy is at work. i'll reread in the am.
i'd have a difficult time ascribing those
numbers to 700c wheels and saying
they're the cat's ess.

[jerk]

my copy is at work. i'll reread in the am.
i'd have a difficult time ascribing those
numbers to 700c wheels and saying
they're the cat's ess.


ahm...that's because you know something about proper bicycle design and jan heine despite a great magazine, awesome taste in wool jerseys, and cool interests; seems to have a difficulty understanding the totality of bike design...which is ironic because the bikes he is into, have the freaking valve stem incorporated into the design of the total product.

focusing on trail is as stupid as focusing on stem length, setback or any other single measurement; except displacement. because as you and the jerk all know, there is no replacement for displacement.

jerk

[e-RICHIE]

ahm...that's because you know something about proper bicycle design and jan heine despite a great magazine, awesome taste in wool jerseys, and cool interests; seems to have a difficulty understanding the totality of bike design...which is ironic because the bikes he is into, have the freaking valve stem incorporated into the design of the total product.

focusing on trail is as stupid as focusing on stem length, setback or any other single measurement; except displacement. because as you and the jerk all know, there is no replacement for displacement.

jerk



hmmm i see we agree (http://forums.thepaceline.net/showpost.php?p=203636&postcount=8) once again atmo.

[dbrk]

When testing the 650B Kogswell the VBQers were using the same frame with three different forks, as I understand it. (Jan is the author but he has co-conspirators, albeit ones I think are apt to be in agreement with him.) The conclusion, if I recall properly, is that the lowest trail fork worked best with the heaviest front load while the highest trail number produced the best ride without a load (and did not fare well with the load on the bars). This focus on trail is, however, in my estimate a mistake insofar as it fails to consider the entirety. I have some experience with 650b and these design issues and don't find myself in agreement with this article's essential conclusions. Our tests too are experiential and pragmatic. Let me also say that I know Jan Heine well, respect him tremendously, and honor his opinions. He is, if you didn't know this, a PhD in geology and understands a good argument and so would not take my differing opinions personally. We are both sorta' stubborn, I suppose, but willing to listen and reply with respect and friendship.

Our own tests have shown that there is a noticeable difference in the way the same frame rides and feels with a short trail (long rake) or long trail (shorter rake) fork. However, our conclusion does not go as far as Jan and company. We did not experience the same handling discomforts with a bag on the longer trail bike. We also think that a competent rider will get used to the changes in rapid form and that it's not really worth the negative implications of less trail unless you are certainly and nearly-always committed to a heavy up front load. I believe this view is also held by other experienced builders using 650B wheels who carry handlebar bags (though I should not like to name names or speak for others). I rarely ride so heavily loaded and camping bikes are generally not great all-around riders. Again, in a constructeur bike--- in which every bit is considered for the entire design--- I am dismayed that there should be this narrow focus on trail, though I confess we have experimented. Our results are different.

ALL that said, to isolate trail can cause one to overemphasize an issue that should not be divorced from the WHOLE design, the gestalt, le configuration (though the French, as far as I understand it would say "construction" for this notion). I find myself in agreement with e-richie, and while that is not the least bit surprising to me, it is a view based on my experience doing these very same tests, not only deference and respect for his superb understanding. Building a bike that handles a reasonable front handlebar load doesn't require multiple trail forks so much as it requires a look at every bit of the whole design, at least that is the way we do it at our company.


dbrk

[catulle]

Gestalt is a, er, German word. Some dudes called Kant and Husserl made it hip, and then the shrinks baptized it to mean that the brain gathers pieces and makes it a whole schtick, atmo. Groovy idea and cool word.

[jerk]

Gestalt is a, er, German word. Some dudes called Kant and Husserl made it hip, and then the shrinks baptized it to mean that the brain gathers pieces and makes it a whole schtick, atmo. Groovy idea and cool word.


don't tell e-richie. he think's it's yiddish.

jerk

[e-RICHIE]

Gestalt is a, er, German word. Some dudes called Kant and Husserl made it hip, and then the shrinks baptized it to mean that the brain gathers pieces and makes it a whole schtick, atmo. Groovy idea and cool word.

no matter, i employ it freely because
it does wonders for my self-esteem.
it makes me feel cosmopolitan, and
that works atmo as does a grand cosmo
now and then.

[News Man]

my copy is at work. i'll reread in the am.
i'd have a difficult time ascribing those
numbers to 700c wheels and saying
they're the cat's ess.


I guess my point in starting this thread was to note the relative scarcity in low trail offerings and to gain some insight into why this was the case. I do understand that trail is just one of many design parameters and to isoloate it as the sole component of stability and cornering response is a bit myopic. I just thought the results (albeit subjective) were interesting in that the performance (as judged by Jan) peaked at high and low trail, but suffered in between. Most bikes being made today seem to be on the high side when it seems the low side is no slouch.

[catulle]

no matter, i employ it freely because
it does wonders for my self-esteem.
it makes me feel cosmopolitan, and
that works atmo as does a grand cosmo
now and then.

Hey, don't listen to Mr. Jerk. He's all uppity 'cause Mrs. Jerk is being canonized. You are cosmopolitan and a real mensch. Mr. Jerk too. I just mentioned that the word was German because the French translation (?) was provided and I didn't want the sterling coherence of the thread to be lost, atmo. Spencer for president.

[e-RICHIE]

I guess my point in starting this thread was to note the relative scarcity in low trail offerings and to gain some insight into why this was the case. I do understand that trail is just one of many design parameters and to isoloate it as the sole component of stability and cornering response is a bit myopic. I just thought the results (albeit subjective) were interesting in that the performance (as judged by Jan) peaked at high and low trail, but suffered in between. Most bikes being made today seem to be on the high side when it seems the low side is no slouch.


the "low trail offerings" are scarce because the type of bicycle
being heralded here is stuck in a time warp and does not know
what it wants to be in 2006. with the exception of a few enthusiasts
making modern incarnations, these (types of) bicycles were developed
and perfected for events that no longer exist in the mainstream.
there are quite a few folks that are now co-opting the term Constructeur
without ever having competed in these events, done a pbp, or the like.
that's not a bad thing nor do i mean it as a criticism. the fact is that
there is a renaissance in this bicycle type - this is good. will folks
use them around town or for actual trials (if they even exist) - who
really knows?! but the answer to your question is that the market
for the frame design in question is so small it is hardly a niche.
well - atmo.

ps i wrote this (http://richardsachs.blogspot.com/2006/04/my-text-from-long-thread-about.html) several months ago and it lives here. (http://richardsachs.blogspot.com)

[dbrk]

snip and snip...wit the exception of a few enthusiasts
making modern incarnations, these (types of) bicycles were developed
and perfected for events that no longer exist in the mainstrea...more snip.

The low trail bike notion tested here in 650B is for pretty heavy front loads and I would call those bikes very exceptional and more like the Adventure Cycling crowd (who are pretty numerous but definitely into schelping their way about!) To wit, these are not really PBP or trials designs but more like camping designs and if they are not, then, well, it makes less sense than I thought.

Using 650B tires and riding in a more relaxed position is indeed not even a niche but a look at Rivendell's Saluki or many other comparable bikes reveals designs not much different than any well-balanced road bike, albeit not for racing and with some important accommodations (such as bb height, etc., for the getting whole in line). What is at stake is not the style of bike as such but the way a tire like a 35mm with far lower tire pressure and more rubber feels on rough roads and very long rides or long WET rides. This particularly sets apart these bikes from skinny tire modern race bikes. There's plenty of room for all sorts of cycling and there's no one bike suited for all, as I know we'd agree.

dbrk

[goonster]

with the exception of a few enthusiasts
making modern incarnations, these (types of) bicycles were developed
and perfected for events that no longer exist in the mainstream.

Maybe not in the mainstream, but the brevets I ride seem to have a healthy (and growing) tournout, and these are pretty discerning riders with money to spend on bikes. It shouldn't take huge volume to support a healthy, mature and committed randobike culture. Even in their heyday, Herse and Singer weren't cranking 'em out for the masses.


there are quite a few folks that are now co-opting the term Constructeur
without ever having competed in these events, done a pbp, or the like.


Simon Firth rode PBP '03, and he has built some very nice Gestalt bikes, but I don't think he claims to be a Constructeur. I don't know what kind of Kool Aid the Bilenky folk are drinking down there in Olney, but I don't think it's French. ;)

[Dr. Doofus]

Gestalt is a, er, German word. Some dudes called Kant and Husserl made it hip, and then the shrinks baptized it to mean that the brain gathers pieces and makes it a whole schtick, atmo. Groovy idea and cool word.

kant, hip?

maybe in the way that wack job fichte got the first critique all wrong after a hippie trek through the massif central...

now hegel was hip, or at least lukacs' version of that guy was

[e-RICHIE]

Maybe not in the mainstream, but the brevets I ride seem to have a healthy (and growing) tournout, and these are pretty discerning riders with money to spend on bikes. It shouldn't take huge volume to support a healthy, mature and committed randobike culture. Even in their heyday, Herse and Singer weren't cranking 'em out for the masses.
no question wrt the money.
but the term mature infers that that the makers go through
the same trials and tribulations that the er, french, did
in all those decades when the problem solving was going
on. yes - these 2 marques were low volume, but they had
the clientele, they had the competition trials, and they prolly
made thousands of frames at the end of the day. (iow, those
bikes and the designs that heine gets all wet and sticky
about didn't just happen for no reason.)
in my eyes, that legitimizes their choices.

Simon Firth rode PBP '03, and he has built some very nice Gestalt bikes, but I don't think he claims to be a Constructeur. I don't know what kind of Kool Aid the Bilenky folk are drinking down there in Olney, but I don't think it's French.
steve's a fellow jew. i suspect it's mogan david in the box.

[goonster]

but the term mature infers that that the makers go through
the same trials and tribulations that the er, french, did
in all those decades when the problem solving was going
on.

Agreed, but with respect to the trials and tribulations, one would hope that today's masters can stand on at least one shoulder of the giants. I think what's going on now is a bit of a process to figger out how some of the ancient ideas can be adapted by today's randonneurs.

All it takes is some sustained demand.


yes - these 2 marques were low volume, but they had
the clientele, they had the competition trials, and they prolly
made thousands of frames at the end of the day.

In the very low thousands each, over twenty years (ca. 200/yr) . . . probably.

In '46 someone will say, "Richie had it easy. His clientele wanted light, pretty bikes, and sometimes races were won on them, and he advertised in VBQ and posted thirty intarwebs daily, and he made, like, hundreds of bikes, all by himself, and they sold despite being so . . . red!" ;)

[jl123]

I think theres more info on the VBQ site about pneumatic trail, here...

http://www.vintagebicyclepress.com/glossary.html

[e-RICHIE]

Agreed, but with respect to the trials and tribulations, one would hope that today's masters can stand on at least one shoulder of the giants. I think what's going on now is a bit of a process to figger out how some of the ancient ideas can be adapted by today's randonneurs.



what is a randonneur in 2006?

[catulle]

kant, hip?

maybe in the way that wack job fichte got the first critique all wrong after a hippie trek through the massif central...

now hegel was hip, or at least lukacs' version of that guy was

If Hegel were around, he'd be making Paris Hilton happy, atmo.

[jerk]

what is a randonneur in 2006?


a guy who is really just a bit too cool for a helmet mirror and an orange vest but still sporting a full on beard and adept at hand signals.

jerk

[palincss]

what is a randonneur in 2006?

One who belongs to a randonneuring organization (ours is RUSA) and participates in organized brevets, of which there are plenty in many places in the country.

[goonster]

what is a randonneur in 2006?

Anybody who regularly rides in rain and darkness, and wishes that sandwiches be readily available at all times and that all those bags, lights, fenders and reflectors be properly part of the bike, instead of clamped and zip-tied on.

It's a Gestalt thing for the RUSA set, atmo. :beer:

As someone who has been doing this kind of riding for a few years, I now realize that my needs would be better met by a bike that has a large bag in the front and permanently affixed metal fenders, than by a "normal" road bike with a largish saddle bag and flimsy plastic fenders, no matter how sweetly that bike may ride. Therefore I will kindly ask the builder of my next bike to conceive of a Gestalt that includes a front bag weighing, say, 8 lbs., without presuming to dictate how much trail that bike should have.

Years ago, trick lighting setups, with concealed wiring and cable-actuated sidewall generators, were the bling. Today, for my own personal requirements, I consider that issue solved by a dynohub with light mounted on the axle, despite the minor inconvenience of not being able to flick the switch while riding.

[e-RICHIE]

One who belongs to a randonneuring organization (ours is RUSA) and participates in organized brevets, of which there are plenty in many places in the country.

tell me, is it simply long(er) distance riding, or is the equipment judged as well? iow, is it the bicycle equivilent of orienteering or rally car racing, or a similar competition, or is it the fastest guy "wins"?

[e-RICHIE]

a guy who is really just a bit too cool for a helmet mirror and an orange vest but still sporting a full on beard and adept at hand signals.

jerk
it's the absolut talking, n'est-ce pas atmo?

[e-RICHIE]

Anybody who regularly rides in rain and darkness, and wishes that sandwiches be readily available at all times and that all those bags, lights, fenders and reflectors be properly part of the bike, instead of clamped and zip-tied on.

It's a Gestalt thing for the RUSA set, atmo. :beer:

but are you competing as well -
or simply riding to ride?

[jerk]

it's the absolut talking, n'est-ce pas atmo?


a little early for that don't you think? where's happy hour?

jerk

[palincss]

I guess my point in starting this thread was to note the relative scarcity in low trail offerings and to gain some insight into why this was the case. I do understand that trail is just one of many design parameters and to isoloate it as the sole component of stability and cornering response is a bit myopic. I just thought the results (albeit subjective) were interesting in that the performance (as judged by Jan) peaked at high and low trail, but suffered in between. Most bikes being made today seem to be on the high side when it seems the low side is no slouch.

Even in France -- even in bicycles made by Herse and Singer -- as riders switched to narrower tires, the bikes got more geometric trail to compensate for the loss of pneumatic trail produced by wide low pressure tires. According to Jan in VBQ, this is what the historical record shows. It's only recently that the tires that are appropriate for use with low trail have become more widely available.

There's also a matter of tradition and knowledge base, I think. The low trail bikes were based on school of design in France. The American bicycle market has been influenced far more by English and Italian builders than French - in fact, it's been what, thirty years? since French bicycles had any market at all in the USA.
And the English always carried the load in the back, while Italian bicycle design (at least, as we know it) is all about racing bikes, where loads aren't carried at all.

Over the course of time basically it seems to me that knowledge of low trail design
has basically been lost; it's only being recovered now by a study of the old bikes and the literature of the time. This has historical precedent: look how long the knowledge of ancient Greece was lost in the west.

[e-RICHIE]

Over the course of time basically it seems to me that knowledge of low trail design
has basically been lost; it's only being recovered now by a study of the old bikes and the literature of the time.

this trail thing is specific, not general. measurements
that conclude these opinions must be exact. when i read
the gaff wrt how they maesured the fork on the gaansari
to draw a conclusion, i lost a little faith in the process.
when they rebounded and realized the error of their ways
and followed by 'splaining that it's common to have fork
blades brazed in slightly rearward in order to yield a fork
that had less offset that the actual blades (have), i lost
a little more faith atmo.

[palincss]

tell me, is it simply long(er) distance riding, or is the equipment judged as well? iow, is it the bicycle equivilent of orienteering or rally car racing, or a similar competition, or is it the fastest guy "wins"?

Everyone who finishes wins, and results aren't published in order of time. Equipment isn't judged. You're confusing randonneuring with the Technical Trials.

Yes, rallies are a very good analogy, in that there are routes to follow, checkpoints that must be made in a specified amount of time (including hidden checkpoints), and as with rallies, reliability of equipment is very important.

We're talking about a sport where the short rides are 200km, and they progress up to 1200 km, that must be completed in 90 hrs or less, I believe. They involve riding at night, and because they take place in the spring, bad weather is common.
Hence lights, fenders, bags. Because time in the saddle is very long, comfort is extremely important; inescapably, riders will be at some point seriously tired, so stability and freedom from over-responsiveness to accidental rider inputs is highly valued. The sort of "responsiveness" that is prized in criterium bikes would be downright dangerous, not to say inappropriate, in a brevet bike.

Typically, riders are self-supported, and need to carry supplies, appropriate clothing, to get them from checkpoint to checkpoint where, I believe, they can get access to drop bags that have been prepositioned for them.

I've never done it, but I've read the reports of a number of brevets. Jan Heine is a randonneur. One of the interesting articles in recent VBQ issues described his 300km brevet on his 1952 Herse Randonneur, where he set a course record.

There are randonneurs here on the list who've done this; please jump in.

[e-RICHIE]

Everyone who finishes wins, and results aren't published in order of time. Equipment isn't judged. You're confusing randonneuring with the Technical Trials.

Yes, rallies are a very good analogy, in that there are routes to follow, checkpoints that must be made in a specified amount of time (including hidden checkpoints), and as with rallies, reliability of equipment is very important.

We're talking about a sport where the short rides are 200km, and they progress up to 1200 km, that must be completed in 90 hrs or less, I believe. They involve riding at night, and because they take place in the spring, bad weather is common.
Hence lights, fenders, bags. Because time in the saddle is very long, comfort is extremely important; inescapably, riders will be at some point seriously tired, so stability and freedom from over-responsiveness to accidental rider inputs is highly valued. The sort of "responsiveness" that is prized in criterium bikes would be downright dangerous, not to say inappropriate, in a brevet bike.

Typically, riders are self-supported, and need to carry supplies, appropriate clothing, to get them from checkpoint to checkpoint where, I believe, they can get access to drop bags that have been prepositioned for them.

I've never done it, but I've read the reports of a number of brevets. Jan Heine is a randonneur. One of the interesting articles in recent VBQ issues described his 300km brevet on his 1952 Herse Randonneur, where he set a course record.

There are randonneurs here on the list who've done this; please jump in.


at a typical event in 2006, what percentage of entrants
are on bicycles that you'd consider store-bought versus
the percentage that are on bicycles made exactly for
this type of use?

[palincss]

this trail thing is specific, not general. measurements
that conclude these opinions must be exact. when i read
the gaff wrt how they maesured the fork on the gaansari
to draw a conclusion, i lost a little faith in the process.
when they rebounded and realized the error of their ways
and followed by 'splaining that it's common to have fork
blades brazed in slightly rearward in order to yield a fork
that had less offset that the actual blades (have), i lost
a little more faith atmo.

The measurements on the historic bikes were taken off the photographs in _The Golden Age_, according to Jan. The way they were photographed made this possible: dead on views with a long lens, etc. , almost the equivalent of engineering drawings. It's a lot more difficult to measure a bike in the flesh, I'd imagine.

One thing I know they are sure about, is the dimensions of the Kogswell P/R prototypes. No guesswork there; they had the blueprints as well as the frames themselves.

[e-RICHIE]

The measurements on the historic bikes were taken off the photographs in _The Golden Age_, according to Jan. The way they were photographed made this possible: dead on views with a long lens, etc. , almost the equivalent of engineering drawings. It's a lot more difficult to measure a bike in the flesh, I'd imagine.

One thing I know they are sure about, is the dimensions of the Kogswell P/R prototypes. No guesswork there; they had the blueprints as well as the frames themselves.

1) i disagree that you can measure a bicycle dimension
from a photograph. i've been on enough shoots to know
that you set the picture to trick the eye into believing
the perspective is dead on, when often the bars are
canted one way, the forks the opposite, and the entire
bicycle is leaning either toward or away from the lens.
all this - so that it looks right to the reader.

2) but the gaansari measurements in the current issue
were taken from the bicycle by the folks shaping the
opinions right now!!

[goonster]

a guy who is really just a bit too cool for a helmet mirror and an orange vest but still sporting a full on beard and adept at hand signals.

jerk

Correct on the beard. Wrong on the mirror.

(scroll down to post #19)

NJ 600km Brevet Report (http://forums.roadbikereview.com/showthread.php?postid=318891#poststop)

tell me, is it simply long(er) distance riding, or is the equipment judged as well? iow, is it the bicycle equivilent of orienteering or rally car racing, or a similar competition, or is it the fastest guy "wins"?


That's a bit of a touchy subject. Officially, everyone competes only with themselves, and everyone is a winner if they finish in the time limit. The person finishing first gets generally gets no special recognition (although sometimes, e.g. PBP, they do award medals for first finishers in different categories). It may sound daft to racers, but it has to be at least as satisfying as "competing" in a race where you bag it with thirty miles to go after working for a teammate who doesn't place.

In reality, there is a bit of low-key nut swinging over low finishing times, but rides are almost always cooperative, and I've never seen anyone try to drop another rider.

To the uninitiated, the time limits for brevets may sound very generous. Normally, they are, but I assure you that if terrain and weather conspire, a ride that looks easy on paper can be very, very difficult to finish. I participated in the ride described above and finished with five minutes to spare, yet I consider it my greatest accomplishment on the bike to date.

The bikes are not judged officially (besides having to pass a lighting and inspection) but there is a lot of overt checking out of other riders' bikes, with respect to creative and elegant solutions to the lighting/storage/rain challenges.

The technical trials may have imparted a certain amount of prestige to the winners, but they were basically a publicity stunt for the constructeurs, and not something that rank and file randonneurs participated in, afaik.

[jl123]

Hey rich-e-yo,
I'd be a little less harsh on Jan. I think he's the only person even bothering to do bicycle comparison and road tests of any depth/length. I mean instead of losing faith in him why not help him out with some advice/expertise? If indeed you have tried that, then please disregard this thought. I think VBQ would certainly be that much better if someone as knowledgable as yourself could offer some advice to them once in awhile. JL

[goonster]

The measurements on the historic bikes were taken off the photographs in _The Golden Age_, according to Jan.

I may have missed something, but this is news to me.

AFAIK, Jan measures all frame dimensions in person, and uses a kind of large adjustable protractor to measure angles. Even then he acknowledges that measuring angles on bikes is fraught with problems. If anyone can suggest a better method, I'm sure he'd be receptive.

I might be wrong though, and can't speak for Jan.

[News Man]

FWIW

I measured the trail on the Weigle last night after reading some of your responses. I think I did it right and it is 60 not 41 as on the Weigle that Jan reviewed.

Seems e-richie, dbrk and others were right on the money.

The bike does ride differently than many of my "race" (you can hardly call what I do on a bike as racing, but I try) bikes with similar amounts of trail. Maybe it's the longer wheelbase or one of the other subtle design aspects that contribute to the whole. Bottom line is, I think the bike is superb and I have learned a few things about "gestalt" bike building.

Thanks all.

[e-RICHIE]

Hey rich-e-yo,
I'd be a little less harsh on Jan. I think he's the only person even bothering to do bicycle comparison and road tests of any depth/length. I mean instead of losing faith in him why not help him out with some advice/expertise? If indeed you have tried that, then please disregard this thought. I think VBQ would certainly be that much better if someone as knowledgable as yourself could offer some advice to them once in awhile. JL


wait - jan and i are familiar with each other and
i consider him a peer. we have spoken about these
types of things many times. i have always taken his
calls and he takes mine as well. and - i am a contract
advertiser-slash-supporter of vbq.
the only advice i would give to anyone riding, writing,
or reading about bicycles is that no one element can
be taken out of context in order to make sweeping
generalizations about how things work. this trail
issue is one example of that.

[e-RICHIE]

I may have missed something, but this is news to me.

AFAIK, Jan measures all frame dimensions in person, and uses a kind of large adjustable protractor to measure angles. Even then he acknowledges that measuring angles on bikes is fraught with problems. If anyone can suggest a better method, I'm sure he'd be receptive.

I might be wrong though, and can't speak for Jan.


you ought not be measuring the angles at all.
use a ruler/tapemeasure, a straight edge, and
a plumb bob and measure the linears. that is
the only accurate way for the layperson to
take and transcribe measurements accurately.

[palincss]

at a typical event in 2006, what percentage of entrants
are on bicycles that you'd consider store-bought versus
the percentage that are on bicycles made exactly for
this type of use?

I'd have to say general purpose bikes fitted out for the task via accessories dramatically outweigh purpose-built constructeur bikes, if the cross section of DC area randonneurs I know is in any way representative. That's not to say there aren't people riding purpose-built customs, of course; consider the Mariposa randonneuring bikes, and in the US Peter Weigle in particular has done some magnificent work in this area.

It's also worth noting that some firms, such as Thorn and George Longstaff in the UK, Heron in the US offer off-the-shelf randonneuring bikes.

Serotta used to have a model that was pretty much randonneuring geometry, in the Rapid Tour. I believe you can get this geometry now in many Serotta models.

The argument can be made that an aftermarket rack will be heavier (the adjustable fittings, nuts and bolts, etc.) than one custom made and integrated ito the bike; and of course, wires that run through the frame are much neater than wires draped all over the frame and held on with zipties. Fenders will fit better and be easier to install if the frame was designed with them in mind - proper fittings, bridges at correct distances, and so on. But that isn't to say that general purpose bikes with appropriate accessories won't or can't work.

[e-RICHIE]

... and in the US Peter Weigle in particular has done some magnificent work in this area.


magnificent is an understatement, but i'll agree with
you. he's the living incarnate of a mid 20th century
rene herse. i would say he's without peer, but that'd
be unfair to those on whom peter has had a headstart
in putting this genre of bicycles in the public's psyche.

[dbrk]

magnificent is an understatement, but i'll agree with
you. he's the living incarnate of a mid 20th century
rene herse. i would say he's without peer, but that'd
be unfair to those on whom peter has had a headstart
in putting this genre of bicycles in the public's psyche.

Not that my opinion is worth a fig and figs notwithstanding but I would reply that Weigle only has peers...and such company is truly exalted:

because that would include _in this very small niche of French-style randonneurs_ only Singer, Toei, Goodrich, and that master of the traditional bicycle Mike Barry. But such a compliment from RS is real testimony. I hope someone offers half as fine an approbation regarding anything I might ever accomplish.

on the list for a JPW, perhaps a year from now, he makes all the choices,

dbrk

[Grant McLean]

Here's a trail chart.


-g

[Grant McLean]

The only way to get low trail numbers (down to sub 40mm) is to go steep
in the head tube angle. This shortens the front center measurement,
which can be compensated for with a longer top tube and a keeping to
a shorter stem to prevent the reach from getting too far out there.

French Fit anyone?

-g

[e-RICHIE]

Not that my opinion is worth a fig and figs notwithstanding but I would reply that Weigle only has peers...and such company is truly exalted:

because that would include _in this very small niche of French-style randonneurs_ only Singer, Toei, Goodrich, and that master of the traditional bicycle Mike Barry. But such a compliment from RS is real testimony. I hope someone offers half as fine an approbation regarding anything I might ever accomplish.

on the list for a JPW, perhaps a year from now, he makes all the choices,

dbrk

agreed on all counts yo atmo.
i'm a demon with those double negatives ("...i would
say he's without peer, but that'd be unfair to those on
whom..."), especially after two grand cosmpolitans. your
list of names echos my inner thoughts, which will have
more clarity after i dine! apologies for any ambiguity.
each of the cats that you name is at the vanguard of
this framemaking niche.

[palincss]

The only way to get low trail numbers (down to sub 40mm) is to go steep
in the head tube angle. This shortens the front center measurement,
which can be compensated for with a longer top tube and a keeping to
a shorter stem to prevent the reach from getting too far out there.

French Fit anyone?

-g

Sorry, but that's incorrect. The Kogswell P/R prototype with the 25mm trail has a 73 degree head angle. You can get there by increasing rake, too -- and the short trail fork has lots of rake. I posted a link to the article; it's all in there, as I recall.

[e-RICHIE]

Sorry, but that's incorrect. The Kogswell P/R prototype with the 25mm trail has a 73 degree head angle. You can get there by increasing rake, too -- and the short trail fork has lots of rake. I posted a link to the article; it's all in there, as I recall.

whadya' suppose that rake is?

[Grant McLean]

Sorry, but that's incorrect. The Kogswell P/R prototype with the 25mm trail has a 73 degree head angle. You can get there by increasing rake, too -- and the short trail fork has lots of rake. I posted a link to the article; it's all in there, as I recall.

With all due respect, that test is meaningless. It boggles my mind that
they would use only 1 head tube angle!!

The whole point of trail
is to balance BOTH headtube angle and forkrake for the resultant trail and front
center that is desired.
Any fool who does a test based on changing ONLY fork rake is missing the
entire point of a great riding design.

The only reason they did the test the way they did was that it was the only
way they could do it with limited resources. They needed to build entirely
different frames to test in impact of trail on the overall ride quality.

In my eyes, their test is like changing chainring sizes, and concluding that
a bigger ring gives you a bigger gear, without even realizing that the
rear cog changes the ratio too. No kidding!?

-g

[whippettanker]

whadya' suppose that rake is?

we've kinda given up on supposition and gone with calculation:

http://kogswell.com/geo.php

the tire diameter of a 584 CdlV is 666mm

Matthew (I'm studying to be a whippet tanker) Grimm

[e-RICHIE]

we've kinda given up on supposition and gone with calculation:

http://kogswell.com/geo.php

the tire diameter of a 584 CdlV is 666mm

Matthew (I'm studying to be a whippet tanker) Grimm

hey matthew -
welcome.
make it easy...
what steve p says about the specs -
what offset are you using to get 25mm of trail?



could it be 74mm fork rake?
or have i worked that page incorrectly?
http://kogswell.com/trail.php?e4.x=12&e4.y=16&h1=666&i1=73&j1=75

[Grant McLean]

we've kinda given up on supposition and gone with calculation:

http://kogswell.com/geo.php

the tire diameter of a 584 CdlV is 666mm

Matthew (I'm studying to be a whippet tanker) Grimm


Thank you!!!! Finally!! some useful info.

With that diameter, 73' head angle needs 74mm of rake to get to 25mm trail.

You don't need a degree in math to know that's going to ride like crap.

Anybody else out there get it??

g

[palincss]

With all due respect, that test is meaningless. It boggles my mind that
they would use only 1 head tube angle!! What point is a 73 angle with
over 7cm of rake?

The whole point of trail
is to balance BOTH headtube angle and forkrake for the resultant trail and front
center that is desired.
Any fool who does a test based on changing ONLY fork rake is missing the
entire point of a great riding design.

The only reason they did the test the way they did was that it was the only
way they could do it with limited resources. They needed to build entirely
different frames to test in impact of trail on the overall ride quality.

In my eyes, their test is like changing chainring sizes, and concluding that
a bigger ring gives you a bigger gear, without even realizing that the
rear cog changes the ratio too. No kidding!?

-g

Grant, I think you are the one missing the point. This wasn't some arbitrary research project inquiring into the effect of trail on bicycle handling.

The Kogswell P/R is going to be available with three fork options, which will give trail of 30, 40 and 50 mm. They were testing the prototypes -- and on the basis of the test, the decision was made to change the trail of the lowest trail model from 25 to 30.

The point of trail, by the way, is to affect handling, not to change the length of front center.

[palincss]

Thank you!!!! Finally!! some useful info.

With that diameter, 73' head angle needs 74mm of rake to get to 25mm trail.

You don't need a degree in math to know that's going to ride like crap.

Anybody else out there get it??

g

Have you ridden it? Have you even read the article, written by people who did ride it? I think what you think you know is based entirely on theory, and you are dismissing out of hand the evidence of people who have actually experienced it.

What do you believe "ride like crap" is like? Can you describe "craplike" characteristics? And what do you base that on?

In fact, I really have to ask, have you ever ridden on a 38x650B tire inflated to 50psi?

[e-RICHIE]

The point of trail, by the way, is to affect handling, not to change the length of front center.


these are inseparable.
everything is connected,
the same goes for what is above the headset;
if you slightly alter the head angle, it repositions
the upper body placement.

[jerk]

the jerk really likes vbq and reads it cover to cover every time it arrives chez jerk. but take it for what it is, a fun magazine written by a hobbyist who writes well but is obviously fairly new to his hobby. he makes up for it in the jerk's eye, by having very good aesethitic and historical taste which is more than can be for most bicycle manufacturers...including the small list of frame builders who do get the totality of bike design idea that the jerk keeps harping on and e-richie is talking about.

by the way, than gaansaari or whatever the hell they tested in the latest issue was mp. you know why? because it was freaking hideous, belonged to no tradition reasonable or otherwise, and basically combined nothing of the best of the modern with nothing of the best of the classic. nonetheless, the jerk is sure it has a wonderful trail measurement and those lugs were mighty pretty.

jerk

[Grant McLean]

Have you ridden it? Have you even read the article, written by people who did ride it? I think what you think you know is based entirely on theory, and you are dismissing out of hand the evidence of people who have actually experienced it.

What do you believe "ride like crap" is like? Can you describe "craplike" characteristics? And what do you base that on?

In fact, I really have to ask, have you ever ridden on a 38x650B tire inflated to 50psi?

Dude, I have credibilty. don't challenge what i know, you'll look bad.

The (lack of) wheel flop of 74mm of rake is what crap is.

The issue you ARE missing is that if you want 25mm of trail,
use a 75' head angle with 63mm of rake. It's way better.

Rene Herse never built a frame with 73' 74mm fork.

g

[jerk]

The point of trail, by the way, is to affect handling, not to change the length of front center.


wow, the jerk hasn't broken out the "i" word in a while....but you sir are an idiot. there is no "point" to trail. it's a measurement! you can not take any of these things out of the context of the totality of the bicycle. the fact that people so fixated on whether the fender lines match the lug shore lines, and that decrease their tire pressure depending on road conditions in the middle of a ride would look at something as meaningless as "trail" floating like marx's table above your head unattached to anything and everything is frustrating, infuriationg and wrong.

if your mind can only focus on one thing when it comes to bike design...focus on weight balance of the rider between the wheels mkay? you'll still be dazed and confused but you'll be better off.

imho bro,
the jerk lives up to his name,

jerk

[Grant McLean]

Sorry, but that's incorrect. The Kogswell P/R prototype with the 25mm trail has a 73 degree head angle. You can get there by increasing rake, too -- and the short trail fork has lots of rake. I posted a link to the article; it's all in there, as I recall.

when I said 'the only way' I meant that if you wanted on purpose to design
a frame from scratch with 25mm of trail, you'd do it with a headtube angle
steeper than 73'.... as in 'the only way to go' would be steep.

g

[goonster]

Dude, I have credibilty. don't challenge what i know, you'll look bad.


I don't have an axe to grind, but I'll take you up on that. ;)


Rene Herse never built a frame with 73' 74mm fork.

You might think that, but you'd be wrong.

Rene Herse Randonneur No. 2 52 (1952)
73 deg head tube, 73 mm fork offset, 26 mm trail. (close enough?)
650B x 39mm tires

"It handles very pleasantly at all speeds. However, switching to to narrow 29mm tires resulted in an unstable bike."

(Source: VBQ Vol. 3 No. 3, pg. 30)

One reason why Jan is writing and theorizing about this stuff is because he came across older bikes that "should", on paper, ride like crap, but don't.

[e-RICHIE]

Rene Herse Randonneur No. 2 52 (1952)
73 deg head tube, 73 mm fork offset, 26 mm trail. (close enough?)
650B x 39mm tires

"It handles very pleasantly at all speeds. However, switching to to narrow 29mm tires resulted in an unstable bike."



you read about the miscue on taking the measuremnt
of the gaansari fork? how do we know that their (the zine's)
method of taking spec is accurate?
ps - what do you know about, as vbq implies, of the trend
in the industry to lean fork blades back of the steering axis
to yield less of a rake than the blades actually have? i have
never heard of this. it seems counterintuitive atmo.

[jerk]

I don't have an axe to grind, but I'll take you up on that. ;)



You might think that, but you'd be wrong.

Rene Herse Randonneur No. 2 52 (1952)
73 deg head tube, 73 mm fork offset, 26 mm trail. (close enough?)
650B x 39mm tires

"It handles very pleasantly at all speeds. However, switching to to narrow 29mm tires resulted in an unstable bike."

(Source: VBQ Vol. 3 No. 3, pg. 30)

One reason why Jan is writing and theorizing about this stuff is because he came across older bikes that "should", on paper, ride like crap, but don't.


73 degree head tube, 73mm fork offset. 26mm trail....this tells the jerk nothing about this bike. you put 650x39mm tires on anything and it'll handle "pleasantly"....doesn't make it any less f'ed up just because it doesn't go over 25kmh...and without the rest of the package no one can say either way whether the bike is good or bad.....

here's the deal....mr. csuska doesn't care what the resulting trail measurement is. no frame builder cares....he cares that he's building a bike that's going to do what it is suppossed to do.....the jerk just appreciates that he still does it in grey market 753 even though he never passe reynold's test...

jerk

[jerk]

you read about the miscue on taking the measuremnt
of the gaansari fork? how do we know that their (the zine's)
method of taking spec is accurate?
ps - what do you know about, as vbq implies, of the trend
in the industry to lean fork blades back of the steering axis
to yield less of a rake than the blades actually have? i have
never heard of this. it seems counterintuitive atmo.

counterintuitive*





*french for re-tarded.

[jerk]

you read about the miscue on taking the measuremnt
of the gaansari fork? how do we know that their (the zine's)
method of taking spec is accurate?
ps - what do you know about, as vbq implies, of the trend
in the industry to lean fork blades back of the steering axis
to yield less of a rake than the blades actually have? i have
never heard of this. it seems counterintuitive atmo.


he probably measured it off of one of those photographs that are better than a blue print because they're in color and not only blue and stuff.

jerk

[Grant McLean]

As has been pointed out, the accuracy of the fork rake measurement is in question.

The greater point is that drawing conclusions on what all low trail bikes
would ride like based on only 1 combination of head tube and various fork rake
is only part of the story. There are other combinations of rake and angle,
that also yield the same trail numbers shown, but none of that was explored in the test,
so i'm unsure of the value of drawing conclusions based on trail numbers
of so few examples alone.

g

[goonster]

you read about the miscue on taking the measuremnt
of the gaansari fork? how do we know that their (the zine's)
method of taking spec is accurate?
ps - what do you know about, as vbq implies, of the trend
in the industry to lean fork blades back of the steering axis
to yield less of a rake than the blades actually have? i have
never heard of this. it seems counterintuitive atmo.

I don't fully understand the business with the Gaansari's fork blades. I've also never heard of this before, and I agree that it doesn't make a whole lot of sense.

As far as VBQ's measuring methods are concerned, I only know what I read.

The same issue quoted above contains a description of his measuring methods and this note on accuracy:

"We estimate the accuracy to be within 3 mm and 0.3 degrees for all measurements" (as applicable to the Herse cited above)

[goonster]

...doesn't make it any less f'ed up just because it doesn't go over 25kmh...

That's a good one! :p

[whippettanker]

The measurements on the historic bikes were taken off the photographs in _The Golden Age_, according to Jan. The way they were photographed made this possible: dead on views with a long lens, etc. , almost the equivalent of engineering drawings. It's a lot more difficult to measure a bike in the flesh, I'd imagine.

One thing I know they are sure about, is the dimensions of the Kogswell P/R prototypes. No guesswork there; they had the blueprints as well as the frames themselves.

Here's how it unfolded for me:

- I noticed that each Golden Age bike was photo'd -orthograpically-

- I was taliking to Jan and I asked him a geometry question about
a GA bike - he response sounded like he had all of the photographs
at hand and could measure them instantly

- it occured to me that geologists are used to taking measurements
from photos (you can't take a piece of Earth back to your lab for
study, so you take a photo)

Way out in front.

Way out.

[whippettanker]

you ought not be measuring the angles at all.
use a ruler/tapemeasure, a straight edge, and
a plumb bob and measure the linears. that is
the only accurate way for the layperson to
take and transcribe measurements accurately.

I've been pondering how to do this.

Thanks, G. You just saved me from have'n ta thinkify all up on this.

[jan heine]

Somebody pointed me to this list, and it was interesting reading. For those who don't know me, I am the editor of VBQ... First of all, I do consider Douglas and Richard friends, so our disagreements are not personal at all.

Douglas, you say you have experimented with trail and came to different conclusions from ours. I'd love to publish the results in VBQ, if they haven't been published elsewhere. I don't want only my stuff to be in VBQ. Like a scientific journal, VBQ has no position in this trail thing. Contact me offlist for format, etc. We can put this into the fall 2006 issue. Then people can evaluate your tests, rather than just hearing oblique references.

I have made a point of putting unsuspecting people on low-trail bikes. They didn't know what the bike was, nor what they were supposed to feel. That they confirm our evaluation is encouraging. That said, I do not believe there is a perfect geometry.

Richard, the discussion here is taken out of context. The 700C table was specifically for 700C x 28 mm tires. As you probably know from your bikes (which aren't high-trail, either), changing from 20 mm tires at 105 psi to 28 mm tires at 75 psi will change the handling of the bike, especially if it doesn't have a ton of trail.

I agree with you that the entire bike is important. The bikes we tested in Vol. 3, No. 3 had similar chainstay lengths and other features to make them comparable. Indeed, it would not make sense to compare a 1980s Crit bike to a 1954 Singer, but when I have two Singers with every measurement almost the same except the fork offset, I think the comparison is apt. Sure, the front-center measurement changes the weight distribution, but adding 10 mm to fork offset changes the center of gravity by about 5 mm... And front-end geometry is important. Peter Weigle's test bike had the front end of my 1954 Singer, but everything else was different (including the chainstays being 20 mm longer), yet both bikes ride very similarly. I had Peter ride the Singer, and he agreed. Furthermore, if my measurements were to totally off, I doubt the two bikes would handle identically, because Peter built off the measurements in VBQ Vol. 3, No. 3.

Regarding our measurements: It's one thing to build a bike on a jig, and another to have a completely assembled bike and measure it without taking it apart completely. Most mags, if they publish measurements at all, trust the builders. We measure every bike ourselves. I am pretty confident in our measurements. The accuracy stated is the worst-case scenario. I have measured a number of bikes where I had no idea about the geometry, and the builders then confirmed I was spot-on. The Kogswells are a case in point - the low-trail bike was built from an older spec sheet, and I thought I got the latest design. After the ride (we always ride first, then measure, to reduce the bias as much as possible), we found that the trail was 25 mm, not 30 mm as we thought. Then the builder confirmed that they had forgotten about the latest spec sheet. Our latest test bike does not match the numbers the builder publishes on their web site at all. When I asked the builder, he confirmed our numbers, and realized that his web site was out of date.

The Gaansari had the fork blades offset a few mm to the rear, not enough to be apparent immediately. That throws things off, because when you put the 4-foot ruler along the head tube and fork blades, you are off by a degree or so. The fact that I knew the measurements had to wrong because the bike didn't ride like the measurements indicated shows that the differences are real.

Rivendell also has their latest fork crowns designed so that the blades are offset backwards. On their bikes, it's totally obvious, because the centerline of the fork blades is about 7 mm behind the centerline of the steerer. So you get a fork with a lot of rake, but less offset.

I have no bones to pick - it doesn't matter to me which bikes ride best. Most people used to assume that "more trail = more stable bike", and so did I. But when I was riding modern "relaxed geometry" bikes for tests in VBQ, and found that especially with a handlebar bag, they lacked the stability of my older machines, I started measuring the old bikes to see how they were different. And the results were surprising, to say the least.

Finally, all of you are welcome to submit your concerns, criticisms, comments, etc., to VBQ.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[jl123]

Jerk,
"fun magazine written by a hobbyist who writes well but is obviously fairly new to his hobby"

Jan is a extremely good long distance rider- quite possibly a better long distance rider than 99% of the visitors to this forum. More-over Jan is able to clearly isolate and discribe a great number of subtle handling characteristics of a great many subtly different rides, and do so over many hundreds of miles. In fact I would go one further and say that he has brought back into awareness (re-discovered); *that is put into specific language where before I could not find such*, many of the handling attributes a bike should posses for long distance riding.

Just quickly glancing an older issue I read from a test about a Berthoud: "The bike requires a little more space than my older randonneur bikes with less trail- riding no-hands..with traffic around did not feel comfortable. The extreme stability on fast downhills means that once a line is chosen around a curve, it is impossible to make corrections- the input required for sudden moves is greater than the weight shifts the rider can execute. At low speeds..on very steep climbs, wheel flop can occur when taking a hand off the handlebars to reach for a waterbottle...the bike then veers off course unexpectedly....At first I found it difficult to spin on the Epervier, and I tended to bog down on long climbs...I suspected the relatively wide Q factor of the cranks as the culpret. I replaced the cranks...reducing the Q factor from 165 to 145mm. The bike was transformed." etc.

Further Rich-imo has stated that he considers Peter Weigle to be at the very top of the heap as a builder of long distance riding bikes. I had the pleasure to speak with Mr. Weigle a few months ago, and he told me what a great rider (they have rode together for many miles) and tester Jan was, indeed, that some of Jan's reiterations and specific commentary about older French design had inspired him to take a closer look at how the best French builders designed their bikes. Weigle also spoke about how in agreement he was with Jan on the specific riding characterics which Jan was able to put into clear prose in the Weigle test.

So going by Rich-e's thinking that Weigle is at the top, if Weigle rates Jan at the top in terms of rider skill and picking out riding characterics, that makes Jan more than "hobbyist". Jan has real skills.

I'm rather surprised and disappointed, especially by those on this thread who will literally write a post about almost any thought that dangles before their minds eye at a moments notice (as they say, at the drop of a dime) that as such, no-one else felt the need to at least take issue with the Jerk's catagorization of Jan. Too bad that. JL

[jan heine]

One more thing, which was stated clearly in the original article titled "Front End Geometry for Different Loads, Speeds and Tire Sizes," is that I do not believe there is one single perfect geometry.

For a racing bike you need a different geometry than for a touring bike. Even at my level (Cat. 2), races rarely go slower than 25 mph (well, except on really steep hills), and rarely last more than 4-5 hours. A bike that handles well at these speeds and at the limit descending will feel quite differently under a century rider at 18 mph.

Also, if you use narrow tires, you need more trail, as you have less pneumatic trail. That is why racing bikes went from low-trail in the 1940s to more trail over time. Also, as the roads got better, bikes didn't have to be as "nimble" (see below) to weave their way around holes and rocks. Eddy Merckx' 1970s bikes were as perfect for his races as Fausto Coppi's 1940s bike were for the very different races of that time.

It also depends on your skill level. Some like a bike that will be hard to budge from a line around a curve, others prefer a bike that is able to change the line when an unforeseen pothole or obstacle appears in its path. The "nimble" bike, however, also will allow you to do stupid things, such as run into the curb.

So I think there are a lot of geometries that work. In fact, most geometries feel remarkably similar - one of the findings of the aforementioned article was that the outliers in the test, bikes with 11 mm trail and 68 mm trail, really don't feel that dramatically different. I could live with either bike, even though neither of them was my favorite. The differences are in the subtle details. For example, I like to eat and stretch while riding uphill, so being able to ride no-hands at moderate speeds is very useful there. And how a bike behaves after 10 hours in the saddle and under a somewhat sloppy rider is not of much interest to a racer, but very important to a randonneur. And handlebar bags have a bad reputation for messing up a bike's handling. We found this to be true because the load magnifies wheel flop. So you need a geometry is designed for carrying a front-end load.

Switching topics a bit, as a scientist, I don't mind at all if people question my findings. Just like in science, all technical articles in Vintage Bicycle Quarterly are reviewed by experts in their field, to avoid embarrassing mistakes. The article in question was reviewed by Jim Papadopoulos, who wrote the chapters on "steering and handling" in the reference book "Bicycle Science" (MIT Press), as well as John Olsen, who also has done a lot of work on the subject. They suggested numerous changes which were incorporated into the article before it was printed. It was Jim who introduced me to the concept of pneumatic trail... The most recent article with the chart was reviewed, among others, by Grant Petersen of Rivendell Bicycle Works.

Finally, somebody asked me how to get a copy of the article. If you are a VBQ subscriber or want to subscribe, drop me a line and I'll send you the issue and take one issue off your future subscription. If you want only that issue (Vol. 3, No. 3), send $ 10 to the address below. The original article is 8 pages long, and I can't lay it all out in this forum.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[Grant McLean]

Also, if you use narrow tires, you need more trail, as you have less pneumatic trail.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

Hi Jan,

Thanks for contributing to the knowledge here.

Can you explain more about what you mean by "pneumatic trail"? There has
been discussion on this list before about what this is, and I don't think
we clearly understood it.

thanks!

-g

[e-RICHIE]

Richard, the discussion here is taken out of context. The 700C table was specifically for 700C x 28 mm tires. As you probably know from your bikes (which aren't high-trail, either), changing from 20 mm tires at 105 psi to 28 mm tires at 75 psi will change the handling of the bike, especially if it doesn't have a ton of trail.
i agree. that is why i posted in the first place.

We measure every bike ourselves. I am pretty confident in our measurements. The accuracy stated is the worst-case scenario.
that sounds oxymoronic.
people are accepting of these measurements,
however accurate or inaccurate, as the gospel,
and turn on every word. the original intent of the
first post has already been revised by the post-er.
The Gaansari had the fork blades offset a few mm to the rear, not enough to be apparent immediately. That throws things off, because when you put the 4-foot ruler along the head tube and fork blades, you are off by a degree or so. The fact that I knew the measurements had to wrong because the bike didn't ride like the measurements indicated shows that the differences are real.
Rivendell also has their latest fork crowns designed so that the blades are offset backwards. On their bikes, it's totally obvious, because the centerline of the fork blades is about 7 mm behind the centerline of the steerer. So you get a fork with a lot of rake, but less offset.
this is the one factoid that confounds me.
designing a fork to lean rearward in order
to negate the offset built into the blade curves
seems counterproductive. what/where is the
genesis of this build detail?

I have no bones to pick - it doesn't matter to me which bikes ride best. Most people used to assume that "more trail = more stable bike", and so did I.
i agree.
i'm a low(er) trail guy.
i'm into more rake getting you less trail
as part of the greater whole. catch gestalt-itis.

[e-RICHIE]

As far as VBQ's measuring methods are concerned, I only know what I read.

The same issue quoted above contains a description of his measuring methods and this note on accuracy:

"We estimate the accuracy to be within 3 mm and 0.3 degrees for all measurements" (as applicable to the Herse cited above)

i would say/think this whether i was following this
thread or not: that's not accuracy, it's generalizing!

[93legendti]

hey...he is trying to have a frank discussion abou the realities of bicycle components...
why don't you talk about the subject of the post and not personally attack a member of this forum in a way that is irrellevent to the post?...as you were,

jerk

------


wow, the jerk hasn't broken out the "i" word in a while....but you sir are an idiot. there is no "point" to trail. it's a measurement! you can not take any of these things out of the context of the totality of the bicycle. the fact that people so fixated on whether the fender lines match the lug shore lines, and that decrease their tire pressure depending on road conditions in the middle of a ride would look at something as meaningless as "trail" floating like marx's table above your head unattached to anything and everything is frustrating, infuriationg and wrong.

if your mind can only focus on one thing when it comes to bike design...focus on weight balance of the rider between the wheels mkay? you'll still be dazed and confused but you'll be better off.

imho bro,
the jerk lives up to his name,

jerk

[e-RICHIE]

93legendti-issimo
are you channeling roy e. munson?

[Grant McLean]

As has been pointed out, the accuracy of the fork rake measurement is in question.

The greater point is that drawing conclusions on what all low trail bikes
would ride like based on only 1 combination of head tube and various fork rake
is only part of the story. There are other combinations of rake and angle,
that also yield the same trail numbers shown, but none of that was explored in the test,
so i'm unsure of the value of drawing conclusions based on trail numbers
of so few examples alone.

g

Ok E-Richie, here I am quoting myself!

The VBQ article hosted on the Kogswell website shows the results of the
test organized in order of their trail. What I wanted to point out was
that it seemed rather a stretch to me to conclude that "trail" was the magic
bullet.

With a wheel diameter of 666mm the following 4 combinations all result
in 40mm of trail, yet all 4 bikes would handle differently because they
have a different front center.

73.5' + 57mm rake = 40mm trail
73.0' + 60mm rake = 40mm trail
72.5' + 62mm rake = 40mm trail
72.0' + 65mm rake = 40mm trail

I was critical of the 25mm trail design earlier in this thread, and it seems
that the Kogswell experiment results would actually agree with me, since
as was already pointed out by Palincss, the Kogswell team went with 30mm
of trail in their lowest trail offering.

g

[e-RICHIE]

With a wheel diameter of 666mm the following 4 combinations all result
in 40mm of trail, yet all 4 bikes would handle differently because they
have a different front center.

this is a no-brainer.
are you blond?

[93legendti]

93legendti-issimo
are you channeling roy e. munson?

Is he on Comcast cable? :)

[Grant McLean]

are you blond?

Yes, I am. ;-)

I was only pointing out that test only included 1 example
from each different trail number. If there were more examples
from each trail, then I would have more confidence in the conclusions,
that is all i'm saying....

g

[jerk]

------


note the jerk took offense on a personal attack not related to the post or the subject...here the jerk's personal attack is clearly linked and relevent to the post; it's on topic and hence fair game. now if the jerk had called him fat, or an idiot when it comes to his politics or his ability at math or juggling, that would have been irrelevent, petty and mean. in this context the jerk is just being petty and mean.

jerk

[jan heine]

Richard,

I don't know why the Gaansari's and the new Rivendell's forks are designed that way. Maybe because fork rake is cool these days among certain circles. I know a few builders who did the opposite in the 1980s, when people wanted bikes without much fork rake. They added rake imperceptibly by starting the bend higher up. It's a "tromp-l'oeil" type thing. (That is French for "mislead the eye.")

But you are asking the wrong guy. I test the bikes, I don't design them.

Pneumatic trail - the best explanation is in Bicycle Science. I'll try here. Basically, when you corner, there is a side force on the front tire. However, where the tire first hits the road, at the front of the contact patch, the tire tread is laid down with no side force - it just comes out of the air. As the wheel rotates, the bike continues to push outward, yet the tire tread is stuck on the road. So the tire deforms. The most deformation is at the rear end of the contact patch. Then, as it leaves the road, the tire springs back. You can hear that springing back under hard cornering.

So you have the tire deforming more at the back than the front. If you imagine a bunch of force vectors going off the tire to the side, with the steerer axis in the middle, you see that this deformation pulls the steering straight. So it acts like geometric trail (the trail everybody talks about), but it's due to the tires. It appears that wider tires and lower pressures both increase pneumatic trail. So you can get away with 25 mm trail on a 38 mm tire at 55 psi, but not on a 20 mm tire at 140 psi.

Head angles: Our original test included two Singers, one with 72 degree and one with 73 degree head angles. The trail figures were similar (the fork offsets were quite different), and the bikes handle similarly. However, I have ridden bikes with 68 degree head angles, and they handle totally differently with the same trail measurement. That is why you have the wheel flop factor, which takes that into account. Our table clearly states that the values are "for head angles between 72 and 74 degrees."

Regarding the accuracy of our measurements - at least we state the accuracy. Everything, whether a measurement or even a finished bike, has tolerances. The head angle on a real bike may be listed as 73 degrees, but it never is exactly 73.000000000 degrees, but perhaps 73.25677 degrees or 72.99999 degrees. And if you can get the fork offset within 1 mm, you are doing pretty well. You have to define what tolerance is acceptable. Among today's bikes, which usually are very close to their spec, I have never found a few mm or 0.3 degree to make a huge difference. Noticeable perhaps, but I wouldn't reject a bike because it's a tad off the spec.

In the end, there seems to be little controversy about the physics or the measurements. It comes down to preferences, usually influenced by how people ride, and that is fine. Your preferences, and riding style, may vary from mine, and thus you'll like a different bike. Or not - as one of my favorite bikes seems to have a geometry very similar to a friend's Richard Sachs.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[e-RICHIE]

Richard,

I don't know why the Gaansari's and the new Rivendell's forks are designed that way. Maybe because fork rake is cool these days among certain circles. I know a few builders who did the opposite in the 1980s, when people wanted bikes without much fork rake. They added rake imperceptibly by starting the bend higher up. It's a "tromp-l'oeil" type thing. (That is French for "mislead the eye.")
i think we're speaking at cross purposes.
in the 80s, as in other eras, folks used different
radiiaiisiu (!!) in the curve to get the dropout at
the correct offset. starting "higher up" does not
change the offset, only the shape of the curve.
my point is that you're arguing that there could
be a reason that a fork blade pair has 47mm of
rake in them and that the builder installs them
cant-ed rearward so that the fork itself has less
rake the the blades themselves. mon dieu* that
sounds like a misinterpretation of what really is
going on atmo.
*french for my dieu.


Regarding the accuracy of our measurements - at least we state the accuracy. <cut>You have to define what tolerance is acceptable. Among today's bikes, which usually are very close to their spec, I have never found a few mm or 0.3 degree to make a huge difference.
the other post-er wrote this:
"As far as VBQ's measuring methods are concerned, I only know what I read.
The same issue quoted above contains a description of his measuring methods and this note on accuracy:
'We estimate the accuracy to be within 3 mm and 0.3 degrees for all measurements' (as applicable to the Herse cited above)"

a 3mm range in estimating accuracy doesn't seem accurate!

[Grant McLean]

Hi Jan,

thanks for the pneumatic trail explaination.

Since you were involved in the test, what would you say is the "outside of the
envelope" when it comes to lowest number trail? It seemed to me there was
some consensus among these "builders of note" that it was around the 4cm range,
which is why there seem to be a greater number of examples of bikes in
that range. Have you measured a Herse or Singer with more than 73mm
of rake? When I saw that number, I thought it had to be the edge. no?

g

[whippettanker]

With a wheel diameter of 666mm the following 4 combinations all result
in 40mm of trail, yet all 4 bikes would handle differently because they
have a different front center.


73.5' + 57mm rake = 40mm trail
73.0' + 60mm rake = 40mm trail
72.5' + 62mm rake = 40mm trail
72.0' + 65mm rake = 40mm trail


So I took the two ends of this sample and plotted them to see what the front centers would be:

http://kogswell.com/images/study57.jpg
73.5' + 57mm rake = 40mm trail


http://kogswell.com/images/study65.jpg
72.0' + 65mm rake = 40mm trail

And what I found was that the front centers are:

73.5' + 57mm rake = 598mm front center
72.0' + 65mm rake = 620mm front center

A whopping 3.6 percent difference.

Statistically insignificant. But you all agree that there will be an appreciable difference in the ride. Do I have that right?

I guess I'm going along w/ Grant on this one. A steeper head angle does seem to be the better way to go. I'd just keep an eye on toe-clip-overlap.




.

[e-RICHIE]

And what I found was that the front centers are:

73.5' + 57mm rake = 598mm front center
72.0' + 65mm rake = 620mm front center

A whopping 3.6 percent difference.

Statistically insignificant. But you all agree that there will be an appreciable difference in the ride. Do I have that right?[/COLOR]

i think a 2cm difference in front center on
these examples would make these two separate
and distinct bicycles, handling-wise. and, don't
neglect what happens to reach; by changing the
head angle, the handlebar assembly ends up in a
different place in space.

[whippettanker]

i think a 2cm difference in front center on
these examples would make these two separate
and distinct bicycles, handling-wise. and, don't
neglect what happens to reach; by changing the
head angle, the handlebar assembly ends up in a
different place in space.

Ah, the reach around. I always forget about the reach around.

What we need are handlebar stems of various lengths to accomodate such differences.

I'm off to the drawing board!

[e-RICHIE]

Ah, the reach around. I always forget about the reach around.

What we need are handlebar stems of various lengths to accomodate such differences.

I'm off to the drawing board!


it's all connected yo. to harken back to
the hypothetical, if i designed something
and it came out 2cm different from planned,
i'd feel i erred or, worse, shortchanged the
client. i think it's difficult to design what's
on the ground without concurrently designing
what's up above. well, maybe it's not that
difficult, but it does seem like you're only
dealing with the bicycle without the rider atop.

[whippettanker]

well, maybe it's not that
difficult, but it does seem like you're only
dealing with the bicycle without the rider atop.


I wasn't dealing with anything.

Grant was talking about different ways to accomplish the same trail.

So reherse Grant on the reach around thing if you're into it.

[e-RICHIE]

I wasn't dealing with anything.

Grant was talking about different ways to accomplish the same trail.

So reherse Grant on the reach around thing if you're into it.

trail is part of the design of a bicycle,
and the design also incorporates the user,
especially these made-to-order jobbies that
everyone is referencing here. that 2cm is
important and part of the whole.

[catulle]

. that 2cm is
important and part of the whole.

Hey, size matters, atmo. :cool:

[whippettanker]

that 2cm is
important and part of the whole.

Important enough to single it out and perseverate on it?

[catulle]

Important enough to single it out and perseverate on it?

Size is all about the whole, atmo.

[e-RICHIE]

Quote:
Originally Posted by e-RICHIE
that 2cm is
important and part of the whole.
Important enough to single it out and perseverate on it?

??
this is a thread about a frame detail that some
folks think is interesting, so interesting in fact,
that there's an article about it. in this thread it
has been established that the accuracy of the
measurements in the article is within 3mm. you
post a hypothetical about the effect of obtaining
the same trail specs vis-a-vis different methods
and note that it yields a change in front center by
22mm on the otherwise same bicycle.

if these measurements are not important enough
to single out, especially when they are not accurately
taken in the first place, then i guess - yes, it's
imporant enough to perseverate on it. if one doesn't,
than what is the sense of obsessing about any of the
other details?

the frame is the frame, and it's not worth much if
all the details are inaccurate or we are dismissive of
them. in bicycle design, front center is part of the balance
that produces confidence inspiring turns and descending,
as well as making sure a rider's upper body is effectively
placed. it is not an afterthought or a resultant distance.
this trail measurement that someone else found interesting
enough to post about because someone else still wrote
about it, is part of the front center measurement
and coexists within it. the "best" trail measurement in the
world is meaningless if the hub axle point is either too
close or too far away from the central movement.

yes - 2cm is important

[Grant McLean]

I demonstrated the importance of front center for myself last year
when i rode some demo six13's. The only geometry difference
between the 52cm and the 53cm is 5mm of top tube, which equals
5mm more front center.

I rode both bikes, and far preferred the longer one. Same trail,
same angles, same fork rake, same handlebar postion (i changed stems,
and spacers). for me, 5mm made a big difference. 20mm is like
raising you seat 20mm, not going to happen! ATMO.

g

[jan heine]

Before I bow out of this discussion - I have a magazine to get to the printer in the next two weeks - a few comments on measuring bikes:

1. Richard claims that an accuracy of +/- 3 mm invalidates any observations VBQ has made. However, taking the Peter Weigle tested a few issues ago - whether its trail measures 41 mm as Peter claims and we measured, or 38 mm (- 3 mm) or 44 mm (+ 3 mm) doesn't really matter. It's a low-trail bike with any of those numbers.

Even if our measurements are totally off, you still have Peter's claim that he built the bike to these specs. I think it is safe to assume that Peter's bike is a low-trail bike, just as he intended it and as we measured. (For those, who don't know Peter Weigle's bikes, they are among the best anywhere, ever built.)

2. Measuring bikes from photos is possible, but Richard is right that it is beyond the scope of most people. You need good photos with no distortion, of course. (Photos taken with your digital camera and a zoom lens do not work!) And you need to position the bikes carefully. To test this, I measured some bikes in our book "The Golden Age of Handbuilt Bicycles" by using the original photos, blown up to larger size. I had measured the same bikes "in the flesh" for the article in VBQ Vol. 3, No. 3. I found that the head angles were exactly the same, whether measured from the photos or in the flesh, while the fork offsets were very close. I trust the fork offsets from the photos a bit less, because it is hard to align the front wheel perfectly.

3. "Measuring linears," as Richard suggested, leads to even greater errors than our method. Even if every single "linear" measurement is accurate within 0.5 mm (and I challenge you to get a plumb bob to line up to 0.5 mm every time you repeat the measurement), these errors add up. And when you extrapolate the linears outward, as you do for trail, the errors get compounded. Jamie Swan explained that nicely in his article on frame alignment in the latest VBQ.

4. Somebody asked about the lowest workable trail number. There are so many factors involved... Certainly, the 1947 Alex Singer was perfectly rideable with 11 mm trail, but I didn't like it. The Rene Herse and Kogswell prototype with 25 mm trail were well-liked by those who tested them. I haven't ridden any bikes that fall in between.

5. Somebody here claimed that Rene Herse never built a bike with a 73 degree head angle and 73 mm fork offset, resulting in 25 mm trail. In fact, he built at least two. A friend in France has one. He measured his, while I independently measured the one I rode for the 300 km brevet over here. My friend is a surveyor, whose job is to measure things accurately. He once spent a year measuring the facade of the palace at Versailles, so they could draw plans of it. Anyhow, when we compared our measurements, they were spot-on, within 1 mm of each other. I've ridden both bikes for quite some distances, and they ride the same, too. So this geometry apparently was standard for "light randonneur" bikes made by Herse at the time in large frame sizes.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[whippettanker]

Quote:
Originally Posted by e-RICHIE
that 2cm is
important and part of the whole.


??
this is a thread about a frame detail that some
folks think is interesting, so interesting in fact,
that there's an article about it. in this thread it
has been established that the accuracy of the
measurements in the article is within 3mm. you
post a hypothetical about the effect of obtaining
the same trail specs vis-a-vis different methods
and note that it yields a change in front center by
22mm on the otherwise same bicycle.

if these measurements are not important enough
to single out, especially when they are not accurately
taken in the first place, then i guess - yes, it's
imporant enough to perseverate on it. if one doesn't,
than what is the sense of obsessing about any of the
other details?

the frame is the frame, and it's not worth much if
all the details are inaccurate or we are dismissive of
them. in bicycle design, front center is part of the balance
that produces confidence inspiring turns and descending,
as well as making sure a rider's upper body is effectively
placed. it is not an afterthought or a resultant distance.
this trail measurement that someone else found interesting
enough to post about because someone else still wrote
about it, is part of the front center measurement
and coexists within it. the "best" trail measurement in the
world is meaningless if the hub axle point is either too
close or too far away from the central movement.

yes - 2cm is important


I'm pretty sure that we all agree that each dimension is important and has a role in the ride.

So there's no denying that 2cm of front center is important.

My question was about the degree to which it is important.

This posting is about 2cm of trail.

You and Grant have added front center to the discussion and y'all seem to think that 2cm of front center makes a difference.

Here's my question in an elemental form:

Ceteris paribus, which would have a larger effect on the nature of the ride? Moving from 50mm of trail to 30 or moving from 600mm of front center to 620?

My guess is trail, the subject of this posting.

If you think that it's front center, I'd like to hear more about that.

[e-RICHIE]

1. Richard claims that an accuracy of +/- 3 mm invalidates any observations VBQ has made. However, taking the Peter Weigle tested a few issues ago - whether its trail measures 41 mm as Peter claims and we measured, or 38 mm (- 3 mm) or 44 mm (+ 3 mm) doesn't really matter. It's a low-trail bike with any of those numbers.
i didn't write that this invaliates your pov.
i am of the opinion that a 3mm difference in a
measurement is one that is not accurately taken.

Even if our measurements are totally off, you still have Peter's claim that he built the bike to these specs. I think it is safe to assume that Peter's bike is a low-trail bike, just as he intended it and as we measured. (For those, who don't know Peter Weigle's bikes, they are among the best anywhere, ever built.)
the thread veered towards the accuracy of the
measurements because one of the subscribers
pointed out just how accurate they were.
wrt peter, i fully agree - and you know as
much from that text i sent you when you
asked for some verbiage to go along with
the vbq article on him.

2. Measuring bikes from photos is possible, but Richard is right that it is beyond the scope of most people. You need good photos with no distortion, of course. (Photos taken with your digital camera and a zoom lens do not work!) And you need to position the bikes carefully. To test this, I measured some bikes in our book "The Golden Age of Handbuilt Bicycles" by using the original photos, blown up to larger size. I had measured the same bikes "in the flesh" for the article in VBQ Vol. 3, No. 3. I found that the head angles were exactly the same, whether measured from the photos or in the flesh, while the fork offsets were very close. I trust the fork offsets from the photos a bit less, because it is hard to align the front wheel perfectly.
i respectfully disagree.
as noted earlier, i have sat in on enough shoots
to know what is set up is for the eye, not the
ruler.
3. "Measuring linears," as Richard suggested, leads to even greater errors than our method. Even if every single "linear" measurement is accurate within 0.5 mm (and I challenge you to get a plumb bob to line up to 0.5 mm every time you repeat the measurement), these errors add up. And when you extrapolate the linears outward, as you do for trail, the errors get compounded. Jamie Swan explained that nicely in his article on frame alignment in the latest VBQ.
i said that method works for the lay person.
for the academics, i would imagine the budget
would allow for a t square or straight edge to
substitute for a plumb bomb. i am sorry that
wasn't clear.

[e-RICHIE]

I

Ceteris paribus, which would have a larger effect on the nature of the ride? Moving from 50mm of trail to 30 or moving from 600mm of front center to 620?

My guess is trail, the subject of this posting.

If you think that it's front center, I'd like to hear more about that.
as noted in other posts, i cannot separate the two details.
frame height, frame length, front center, trail, cg, cpg, and
overall wheelbase work in harmony to yield the desired solution.
added to this, the rider's, contact points must work effectively
above and between the wheels once they are added to the chosen
frame design. this 2cm variable** that's getting tossed around
is outside the scope of what i would consider a tight tolerance.


** as well as the 3mm margin of error noted elsewhere

[SamIAm]

as noted in other posts, i cannot separate the two details.
frame height, frame length, front center, trail, cg, cpg, and
overall wheelbase work in harmony to yield the desired solution.
added to this, the rider's, contact points must work effectively
above and between the wheels once they are added to the chosen
frame design. this 2cm variable** that's getting tossed around
is outside the scope of what i would consider a tight tolerance.


** as well as the 3mm margin of error noted elsewhere

I feel fortunate to have a bike on order with this man. So much passion combined with experience and a refusal to compromise is a powerful combination.

[Grant McLean]

5. Somebody here claimed that Rene Herse never built a bike with a 73 degree head angle and 73 mm fork offset, resulting in 25 mm trail. In fact, he built at least two. A friend in France has one. He measured his, while I independently measured the one I rode for the 300 km brevet over here. My friend is a surveyor, whose job is to measure things accurately. He once spent a year measuring the facade of the palace at Versailles, so they could draw plans of it. Anyhow, when we compared our measurements, they were spot-on, within 1 mm of each other. I've ridden both bikes for quite some distances, and they ride the same, too. So this geometry apparently was standard for "light randonneur" bikes made by Herse at the time in large frame sizes.

www.vintagebicyclepress.com

For the record, it was I who said they didn't use "74mm" rake. I was making a specific
point, so your comments are made without the context. My point is that I was
speculating that this was as far as it goes: 73mm was the most rake used.
If 73 isn't the most ever, what is? 80? 90? 100?

The reason for my particpation in this discussion was to establish just what
is "outside of the envelope" of trail. Nobody is going to get too excited if
we were discussing 40-60mm, right? The only disagreement is where the
line is drawn. My impression was that these 73mm rake bikes were
pretty specific use bikes, for carrying weight on the front wheel. Not
something designed for everybody.

-g

[jl123]

E-rich,
"i said that method works for the lay person.
for the academics, i would imagine the budget
would allow for a t square or straight edge to
substitute for a plumb bomb. i am sorry that
wasn't clear."

That is insulting to Jan's intelligence. You suggest, no actually you come right out and clearly state that instead of what-ever it is he is doing now, he should be using a T-square and straight edge. This statemnt directly means that you believe that Jan has not already thought or utilized this basic means of measurement, or that indeed if he has used it he has done so incorrectly: using a T square and striaght edge. And further that this technique is your perscription for how he should measure frames in order to stop getting inaccurate results.

Thats unfortunate that you do not hold some of his basic technical skills as competent. Whats even more unfortunate is that you air your belief in his questionable technical skill on a public forum without first asking him what his methods are. E you doubt Jan too much, and you are quicker to judge ("lose faith" as you wrote) him than you are to ask him. And instead of questioning him in a forum that he did not even know about, why not question him as the peer you say he is, directly. JL

[whippettanker]

as noted in other posts, i cannot separate the two details.
frame height, frame length, front center, trail, cg, cpg, and
overall wheelbase work in harmony to yield the desired solution.
added to this, the rider's, contact points must work effectively
above and between the wheels once they are added to the chosen
frame design. this 2cm variable** that's getting tossed around
is outside the scope of what i would consider a tight tolerance.


** as well as the 3mm margin of error noted elsewhere


Here's the complete text of a posting of your's from this thread:

i think a 2cm difference in front center on
these examples would make these two separate
and distinct bicycles, handling-wise. and, don't
neglect what happens to reach; by changing the
head angle, the handlebar assembly ends up in a
different place in space.

It seemed to me that in this posting you were separating details.

If not then I beg your pardon.

Your gestalt/holistic view is clearly the way to approach design.

I think it might be good to give you a little background re how the P/R was 'designed'. It started off to be porteur model and so a couple of different Herse porteur models were measured. The porteurs had extremely low trail because they were used to carry large newpapers loads, in some cases 50kg of papers. So Grant's conjecture that such a bike would not ride well is in fact right, if you leave the load off. Along the way it came to our attention that Herse randonneur bikes had frame geometries that were very close to the porteurs. They differed mostly in the trail. So we reasoned that RH knew what he was doing and that if we offered forks with more trail the same frame could be used by porteurs and randonneurs alike. We ended up with three forks and so the VBQ article is a report on how those three forks work with the same frame.

It's not custom work. It's production work. And there are different objectives in production work. You've had experience in the world of production bicycle, right? You know what I'm talking about.

The bottom line is that we chose a test team that has considerable experience with the kind of riding that these bikes are designed for and not one of them has volunteered to send her test bike back.

[jerk]

enough is enough. the test in question proved nothing except what changing the forks on an individual bicycle did to the perceptions of three individuals who rode those bicycles. as for removing trail out of the totality of bicycle design; there is no point and it serves no purpose. as the jerk said in an off-forum email to some friends, mr. csuska doesn't give a flying gauloise what the heck the trail measurement of the last bike he built is. he does what he does becuase it works, it worked in the past and his experience and that of his customers suggests that it'll work in the future. any attempt to deduce or explain bicycle design that is honed on years of experience in the real world, to simple "experiments" basded on a single variable is an excericise in futility.

a scientific approach is a good thing, but proper bicycle design is a result of a myriad of factors and considerations. whether it is tradition, conscious choice, or some other factor that caused them to work is irrelevent. a great bike is a great bike because it exists as a totality.

details are in the deity in this case; but extracting them from the whole must be done with care.

jerk

[e-RICHIE]

E-rich,
"i said that method works for the lay person.
for the academics, i would imagine the budget
would allow for a t square or straight edge to
substitute for a plumb bomb. i am sorry that
wasn't clear."

That is insulting to Jan's intelligence. You suggest, no actually you come right out and clearly state that instead of what-ever it is he is doing now, he should be using a T-square and straight edge. This statemnt directly means that you believe that Jan has not already thought or utilized this basic means of measurement, or that indeed if he has used it he has done so incorrectly: using a T square and striaght edge. And further that this technique is your perscription for how he should measure frames in order to stop getting inaccurate results.
if he or anyone is getting results, posting them as
accurate, i would believe them, esp if they had
the mission statement of a vbq. however, another post-er
here made the mention that the measurements were
accurate to 3mm - and that those were jan's "words".
whatever jan et al uses or has used, once it's "out
there" that the margin of error encompasses 3mm
wrt to a frame detail that is under scrutiny, i sit up
and notice.
to tell you the truth, while i do know what trail is and
does, i normally don't read articles about it. that is no
slight on vbq, but i am not a tech head and i have never
been into analyzing frame design. i know what i know
from being around bicycles. period. i only read the text
because the o.p. was so compelling. and - isn't it a
bit ironic that the o.p. chimed in later and revised his
point of view?

Thats unfortunate that you do not hold some of his basic technical skills as competent. Whats even more unfortunate is that you air your belief in his questionable technical skill on a public forum without first asking him what his methods are. E you doubt Jan too much, and you are quicker to judge ("lose faith" as you wrote) him than you are to ask him. And instead of questioning him in a forum that he did not even know about, why not question him as the peer you say he is, directly. JL
we all have basic skills that can be improved upon.
lord knows i am still trying to dial it in here atmo.
but as far as the doubting goes, why shouldn't i?
why shouldn't anyone who knows what goes where
read some of this and question the stated result,
especially after the other post-er "outs" that 3mm
thang? like i said, had he not brought that factoid
to this discussion, perhaps it wouldn't be as interesting
to me. oh - and furthermore, jan only became a forum
member half way through this thread. from that point
on i have posted replies to him. before he joined, i was
unable to "ask him", as you suggest i do.
lastly - don't make this a personal issue. i have good a
rapport with jan and my support of the zine began from
day one. i link his site. i take big effin' ads. i pay my
bills. and i enjoy his enthusiasm for what he does, even
if i don't agree with some of the findings atmo.

[catulle]

[QUOTE=e-RICHIE]

I believe it is a privilege to have someone with over thirty years experience building bicycles, which are presently reputed to be the best built in the world, expressing his opinion about a bicycle article. Moreover, we can only learn from this thread. This is not a discussion between opinionated idiots but between very serious and knowledgeable cycling people. I'd like to thank e-RICHIE and Jan and the other serious debaters for taking the time to invest in this discussion, atmo.

[jl123]

E-rich said:

"jan only became a forum
member half way through this thread. from that point
on i have posted replies to him. before he joined, i was
unable to "ask him", as you suggest i do."

but just before said:

"wait - jan and i are familiar with each other and
i consider him a peer. we have spoken about these
types of things many times. i have always taken his
calls and he takes mine as well."

I Jeremy believe your not being fair.

And e-rich I do not speak for Jan, I speak for myself. I believe that Jan makes every effort to measure bikes as well as anyone can, without having to resort to very expensive aparatus. In fact months ago I e-mailed Jan as to how he DOES measure bikes and this is what he wrote:
"T-square's are not often accurate, as even 0.1 degrees off horizontal at the top tube would get you a huge inaccuracy at the BB or similar areas. And no bike I ever have seen had an exactly level top tube. (There are so many variables, for example, how much you face off at the bottom headlug and on top of the fork crown, plus headset stack height affect your head and thus top tube angle.)
I measure with an angle finder for angles (placing the bike on a very straight 6x6 piece of wood that I level with a spirit level. I use a ruler to measure tube lengths. I use a very long ruler as reference by aligning it along the center of the head tube/fork blades, and a T-square off that for fork offset."

The bottom line is that you have stated that Jan has not known how to measure the geometry of a bike frame correctly, and I believe he does as well as anyone could- that is as well as anyone can without resorting to expensive machinery.

[e-RICHIE]

E-rich said:

"jan only became a forum
member half way through this thread. from that point
on i have posted replies to him. before he joined, i was
unable to "ask him", as you suggest i do."

but just before said:

"wait - jan and i are familiar with each other and
i consider him a peer. we have spoken about these
types of things many times. i have always taken his
calls and he takes mine as well."

I Jeremy believe your not being fair.

And e-rich I do not speak for Jan, I speak for myself. I believe that Jan makes every effort to measure bikes as well as anyone can, without having to resort to very expensive aparatus. In fact months ago I e-mailed Jan as to how he DOES measure bikes and this is what he wrote:
"T-square's are not often accurate, as even 0.1 degrees off horizontal at the top tube would get you a huge inaccuracy at the BB or similar areas. And no bike I ever have seen had an exactly level top tube. (There are so many variables, for example, how much you face off at the bottom headlug and on top of the fork crown, plus headset stack height affect your head and thus top tube angle.)
I measure with an angle finder for angles (placing the bike on a very straight 6x6 piece of wood that I level with a spirit level. I use a ruler to measure tube lengths. I use a very long ruler as reference by aligning it along the center of the head tube/fork blades, and a T-square off that for fork offset."

The bottom line is that you have stated that Jan has not known how to measure the geometry of a bike frame correctly, and I believe he does as well as anyone could- that is as well as anyone can without resorting to expensive machinery.


you know - you're right.
i'm not being fair.

since you are the one doing the cut and pasting,
i will ask you - with all these checks and balances,
how does one accept a 3mm margin of error?

[jerk]

E-rich,
"i said that method works for the lay person.
for the academics, i would imagine the budget
would allow for a t square or straight edge to
substitute for a plumb bomb. i am sorry that
wasn't clear."

That is insulting to Jan's intelligence. You suggest, no actually you come right out and clearly state that instead of what-ever it is he is doing now, he should be using a T-square and straight edge. This statemnt directly means that you believe that Jan has not already thought or utilized this basic means of measurement, or that indeed if he has used it he has done so incorrectly: using a T square and striaght edge. And further that this technique is your perscription for how he should measure frames in order to stop getting inaccurate results.

Thats unfortunate that you do not hold some of his basic technical skills as competent. Whats even more unfortunate is that you air your belief in his questionable technical skill on a public forum without first asking him what his methods are. E you doubt Jan too much, and you are quicker to judge ("lose faith" as you wrote) him than you are to ask him. And instead of questioning him in a forum that he did not even know about, why not question him as the peer you say he is, directly. JL


now you are turning this whole debate against the notion of debate itself? what is your problem? e-richie questioned the validity of the measurements and their conclusions after the validity of the measurements was brought into question in the article itself! because you read it in a magazine does not make it beyond scrutiny, in fact the fact that it is published opens it to scrutiny. you clearly do not understand bicycle design and can not refute the argument that no frame builder worth his salt gives a f%$%^ what the trail measurement is removed from the rest of the design so you decide to protect the author's "feelings"? NO ONE CARES ABOUT TRAIL! riders and frame designers care about bicycles and balance of which trail is a funny number derived from two other measurements that may or may not be relevent to anything. anybicycle designed around achieving a certain "trail" measurement is an incomplete design at best. for the umpteenth time, jan heine would have been better served riding three bicycles set up exactly the same but for the tire pressure....it would have actually produced a semblence of a real world conclusion.

if you want to pick on someone, pick on the jerk. he's only a subscriber.
e-richie is an advertizer and a reader and has more right than anyone to examine and question the content.

jerk

[e-RICHIE]

e-richie is an advertizer and a reader and has more right than anyone to examine and question the content.

jerk



do you really think that if i read books or watched tv, i would
be here trying to work my intellect and exorcize all those demons
that re-appear cuzza i gave up a creative writing interest, was gonna
go to a fine anti-war hippie school to have fun, date, and write for
4 effin' years - gave all that up for a gig with a torch?
this is payback atmo.

[jerk]

do you really think that if i read books or watched tv, i would
be here trying to work my intellect and exorcize all those demons
that re-appear cuzza i gave up a creative writing interest, was gonna
go to a fine anti-war hippie school to have fun, date, and write for
4 effin' years - gave all that up for a gig with a torch?
this is payback atmo.


yeah, so what. the jerk won socks and you got to ride today. misery poker score: jerk 1....
e-richie...0

plus, no one ever accused you of reading a book. the jerk accussed you of reading a black and white bicycle fanzine written in the best punk rock tradition even if the writer/owner/publisher doesn't know it.

[Dr. Doofus]

doof will now ingratiate himself with everyone

one variable does not, by itself, create handling characteristics

guys who build bikes understand bike design

guys who don't build bikes don't

guys who don't design bikes who argue about bike design with guys who do provide lots of chuckles

one day doof will accurately measure the trail of whipped creme on vanessa paradis

(he can dream)

[jerk]

you accuse the jerk of not understanding bicycle desing and then you tarnish the image of the jerk's girlfriend with your sick fantasy?

not all guys who build bikes understand bicycle design.

and vanessa prefers creme fraiche doofus. show some respect.

jerk

doof will now ingratiate himself with everyone

one variable does not, by itself, create handling characteristics

guys who build bikes understand bike design

guys who don't build bikes don't

guys who don't design bikes who argue about bike design with guys who do provide lots of chuckles

one day doof will accurately measure the trail of whipped creme on vanessa paradis

(he can dream)

[Ray]

guys who build bikes understand bike design

guys who don't build bikes don'tThere was nothing in this thread I'd have been willing to touch with a ten-foot pole until now. This, though, I find to be quite right from my extremely limited personal experience. I don't build (or design) bikes. I once thought I knew a lot about bike design and the interplay of the variables that go into it. Then I finally had a guy who designs bikes design me a bike. It's the best bike in the world (for me and the limited demands I put on it). I am now quite totally certain that I know SQUAT about bicycle design.

Maybe there are some people who don't build or design bikes who understand bike design as well as those who do. But I bet there are very very damn few.

I like not knowing more than I used to think I liked knowing. I have a lot less to think about and I love the riding more than ever.

-Ray

[e-RICHIE]

There was nothing in this thread I'd have been willing to touch with a ten-foot pole until now. This, though, I find to be quite right from my extremely limited personal experience. I don't build (or design) bikes. I once thought I knew a lot about bike design and the interplay of the variables that go into it. Then I finally had a guy who designs bikes design me a bike. It's the best bike in the world (for me and the limited demands I put on it). I am now quite totally certain that I know SQUAT about bicycle design.

Maybe there are some people who don't build or design bikes who understand bike design as well as those who do. But I bet there are very very damn few.

I like not knowing more than I used to think I liked knowing. I have a lot less to think about and I love the riding more than ever.

-Ray




great initials atmo

[catulle]

one day doof will accurately measure the trail of whipped creme on vanessa paradis

(he can dream)

The Doof'd have to cream too, atmo. :cool:

[catulle]

do you really think that if i read books or watched tv, i would
be here trying to work my intellect and exorcize all those demons
that re-appear cuzza i gave up a creative writing interest, was gonna
go to a fine anti-war hippie school to have fun, date, and write for
4 effin' years - gave all that up for a gig with a torch?
this is payback atmo.

Meet you in Provo under Diogenes' lantern, atmo. Hippie chicks are good for the torch, iirc.

[e-RICHIE]

okay - redemption time.
sorry for all the innuendo and double entendre atmo.
i'm agitated. i have been since len bias sam cooked
himself. i have been since bird retired. the 80s celts
were my real muse. i miss the parquet. the banners.
the post seasons. red and the cigars. life has been
different since the winning ended. we took the pipe
at the end of the 80s.
even the music was better then.

hey - thanks for reading.

[jerk]

okay - redemption time.
sorry for all the innuendo and double entendre atmo.
i'm agitated. i have been since len bias sam cooked
himself. i have been since bird retired. the 80s celts
were my real muse. i miss the parquet. the banners.
the post seasons. red and the cigars. life has been
different since the winning ended. we took the pipe
at the end of the 80s.
even the music was better then.

hey - thanks for reading.


yeah and between cocaine and the movie "celtic pride" starring dan akroyrd the team will never recover.

[Dr. Doofus]

okay - redemption time.
sorry for all the innuendo and double entendre atmo.
i'm agitated. i have been since len bias sam cooked
himself. i have been since bird retired. the 80s celts
were my real muse. i miss the parquet. the banners.
the post seasons. red and the cigars. life has been
different since the winning ended. we took the pipe
at the end of the 80s.
even the music was better then.

hey - thanks for reading.


ainge is waiting for you in provo

doof was always more of a bill lee guy

[jerk]

ainge is waiting for you in provo

doof was always more of a bill lee guy


the jerk'd like to see schilling pitch a perfect game on l.s.dose.



jerk

[Dr. Doofus]

the jerk'd like to see schilling pitch a perfect game on l.s.dose.



jerk

that was doc ellis

[jerk]

that was doc ellis


yeah, the jerk knows. but it should have been the space man. plus ellis walked eight, it was a mere no-hitter.

jerk

[Grant McLean]

I'm pretty sure that we all agree that each dimension is important and has a role in the ride.

So there's no denying that 2cm of front center is important.

My question was about the degree to which it is important.

This posting is about 2cm of trail.

You and Grant have added front center to the discussion and y'all seem to think that 2cm of front center makes a difference.

Here's my question in an elemental form:

Ceteris paribus, which would have a larger effect on the nature of the ride? Moving from 50mm of trail to 30 or moving from 600mm of front center to 620
My guess is trail, the subject of this posting.
If you think that it's front center, I'd like to hear more about that.

Matthew,
It's clear to me you've actually read most of these postings, and are
trying to learn somthing here. That's cool. That's also what
gets me up in the morning too. Maybe we'll get to ride together
some time, that'd be great.

I am confused as to why we have to choose what's more important
in these design criteria. Here's my last thought on the subject:

Is it more important to look "left" or "right" at a railroad crossing,
before Tom Boonen rides around the lowered gates?

My guess is you'd have a hard time choosing to look only one way, right?

Trail and Front center should be thought of as inseperable. The whole
is the whole. Everything matters.

g

[whippettanker]

Matthew,
It's clear to me you've actually read most of these postings, and are
trying to learn somthing here. That's cool. That's also what
gets me up in the morning too. Maybe we'll get to ride together
some time, that'd be great.

I am confused as to why we have to choose what's more important
in these design criteria. Here's my last thought on the subject:

Is it more important to look "left" or "right" at a railroad crossing,
before Tom Boonen rides around the lowered gates?

My guess is you'd have a hard time choosing to look only one way, right?

Trail and Front center should be thought of as inseperable. The whole
is the whole. Everything matters.

g

I do look both ways.

Comes from living in England for a time.

Now about variables....

Let me repeat myself: the Herse bikes varied only by offset. We got that from measurement.

I can see why you'd think that, perhaps in some sort of Absinthe induced state of insanity, we just up and chose to vary only one dimension. The report gives no indication that we did otherwise.

But that's not the case.

We just did what RH did.

Had RH varied everything, we would have too.

But he didn't. So we didn't.

Does that clear things up?

Thanks for the kind words. I do try to learn. I take things very methodically and I test them and I ride them to see what they do and then I put them into my big model and go on.

And as much as I like to learn, my need to understand is dwarfed by Jan's. No one dogs the truth like this guy. Stay tuned. Subscribe. Opportunities like this don't come along often.

[Grant McLean]

We just did what RH did.
Had RH varied everything, we would have too.
But he didn't. So we didn't.
Does that clear things up?

Thanks for the kind words. I do try to learn. I take things very methodically and I test them and I ride them to see what they do and then I put them into my big model and go on.

And as much as I like to learn, my need to understand is dwarfed by Jan's. No one dogs the truth like this guy. Stay tuned. Subscribe. Opportunities like this don't come along often.

I hear you. I get it. The test was the test. The point I was
making was the test does not fit the write up.

http://kogswell.com/testPR.pdf

The article Jan wrote summarizes everything by "trail".
It didn't sort all the results by "rake". The article makes
assumptions about ride characterists based on changes to
both front center and trail, and attributes these qualities
only to trail. That's my only beef. What people posted here
was that they took away from the article was what different
"trail" bikes ride like. That's not the truth. Bikes with the
same trail can ride very differently, and bikes with different
trail numbers can ride very much the same.

From several emails from people (I think you know who)
who disagreed with my comments, it became clear to me
that they didn't know what front center was, or that it affected
anything. It was called "left over" or "resultant". It's not.

You were the only one here who looked at my 4cm trail example
and ran the 4 variations into the calculator, and seemed to get it.
I don't see why we're still talking about this. It's time for
someone to say "wow, gee grant, I get your point, the article
did only mention trail"... anyway. Thanks for discussing!

cheers

-g

[e-RICHIE]

From several emails from people (I think you know who)
who disagreed with my comments, it became clear to me
that they didn't know what front center was, or that it affected
anything. It was called "left over" or "resultant". It's not.


it's not here either.
i build to a front center first. of course, frame height,
length, cg, and cpg are part of the design set up, but
for every frame made and for each rider atop, i have a
FC©™® in mind. with all the other vairables contributing to
the stew, i want that FC©™® to be within range of 2mm or
so at the end of the build. if, while fixturing, i need to
alter specs to get the FC©™® i desire, i edit the offset and/
or the head angle so that the front axle ends up where
i want it - or, better stated - it ought to be.

offset, head angle, and trail (and top tube) are resultant
choices that allow me to arrive at the FC©™® that i
feel will best complete the picture. (that picture includes
a rider yo).

ftr, all of my trails are on the low side using lotsa fork
rake - this is part of the whole. but i do not agonize on
a particular frame if the head angle changes by 4 minutes
or the offset is 2mm different than first chosen. these
details are flexible. they are a means to an end, not
the end. the FC©™® is the "go to" measurement.
it's not a "left over" or "resultant" one atmo!

[jan heine]

Richard,

Planning out the next few issues of VBQ this morning, I had an idea...

I am sure VBQ readers would love to learn more about the "gestalt" approach of designing bikes, and your emphasis on front-center. How about you write this up in the VBQ "Builders Speak" series? You know how it works - a few photos or drawings, your text. You get to say what you want...

I can put your article into the Fall 2006 issue. I am looking forward to that issue - there will be some great stuff in there.

What do you think? Please contact me directly, as I don't follow this list very closely.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[e-RICHIE]

Richard,

Planning out the next few issues of VBQ this morning, I had an idea...

I am sure VBQ readers would love to learn more about the "gestalt" approach of designing bikes, and your emphasis on front-center. How about you write this up in the VBQ "Builders Speak" series? You know how it works - a few photos or drawings, your text. You get to say what you want...

I can put your article into the Fall 2006 issue. I am looking forward to that issue - there will be some great stuff in there.

What do you think? Please contact me directly, as I don't follow this list very closely.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com



you're more than welcome to peruse this (http://richardsachs.blogspot.com)
i am happy to chat anytime, as you know from past
phone calls. you can cull all the blog entries and
phone replies and edit these into a workable text, i am
sure. as far this specific request, here on a public
forum goes - well, thanks, but this is a public forum,
not a place to solicit. i appreciate the sentiment, but
i'll willingingly link you to the 40thou plus words in the
blog and encourage you to find pertinent entries. if
you can't, i'll try. the best we can do is to use
existing material in a new format.

[Johny]

Richard,

Planning out the next few issues of VBQ this morning, I had an idea...

I am sure VBQ readers would love to learn more about the "gestalt" approach of designing bikes, and your emphasis on front-center. How about you write this up in the VBQ "Builders Speak" series? You know how it works - a few photos or drawings, your text. You get to say what you want...

I can put your article into the Fall 2006 issue. I am looking forward to that issue - there will be some great stuff in there.

What do you think? Please contact me directly, as I don't follow this list very closely.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

gestalt 101???

[Johny]

you're more than welcome to peruse this (http://richardsachs.blogspot.com)
i am happy to chat anytime, as you know from past
phone calls. you can cull all the blog entries and
phone replies and edit these into a workable text, i am
sure. as far this specific request, here on a public
forum goes - well, thanks, but this is a public forum,
not a place to solicit. i appreciate the sentiment, but
i'll willingingly link you to the 40thou plus words in the
blog and encourage you to find pertinent entries. if
you can't, i'll try. the best we can do is to use
existing material in a new format.

You mean we'll read this in the fall issue:

Editor: My theory of "your trail is too long" has been challenged by a few infamous Serotta forumites.
MG: Yeah, they are a bunch of ***** who don't know RH at all.
...
...
...

RS, dbrk, Jerk,Gee-man are our guests from the Serotta forum.
RS: It's the gestalt.
...
dbrk: We did the right experiments and our results can not agree with your conclusion.
...
Jerk: %$&^^@...You don't understand anything!
...
Gee-man: Watch out when you cross the railway.

Editor: These represent ONLY their own opinions. If you ride a long-trail bike that results in an accident, don't sue us.

[e-RICHIE]

You mean we'll read this in the fall issue:

Editor: My theory of "your trail is too long" has been challenged by a few infamous Serotta forumites.
MG: Yeah, they are a bunch of ***** who don't know RH at all.


lots/laughs atmo.
but the theory has not been challenged.
my trails veer to the short side, as stated.
they just don't control my bikes - they are
part of them!

[Dr. Doofus]

personal taste

doof likes short f-c, less than 55mm of trail, and a long azzed stem -- faster you go, the better it feels*...whoever designed doof's ridley knew what they were doing



*said in full knowledge that trail and f-c only work in the context of bb height, rear-center, and whether you're riding the right dang size thing to begin with, so your weight is distributed properly....

[David Kirk]

lots/laughs atmo.
but the theory has not been challenged.
my trails veer to the short side, as stated.
they just don't control my bikes - they are
part of them!

This is all so confusing to me. Would any reasonable person pick a new frame based on purely on BB drop, or chainstay length, or fork rake, or etc?

As E.R. has said so many times you can't take any given spec out of the context of the complete design. One or two or three numbers alone won't make or break a design but it's how all the numbers work together that matters.

For many years Merckx didn't list head tube angles or fork rakes on thier spreads sheets. It's easy to understand his motivation if folks are picking thier new bike by a single number.

The soapbox is all yours.

Dave

[Dr. Doofus]

This is all so confusing to me. Would any reasonable person pick a new frame based on purely on BB drop, or chainstay length, or fork rake, or etc?

As E.R. has said so many times you can't take any given spec out of the context of the complete design. One or two or three numbers alone won't make or break a design but it's how all the numbers work together that matters.

For many years Merckx didn't list head tube angles or fork rakes on thier spreads sheets. It's easy to understand his motivation if folks are picking thier new bike by a single number.

The soapbox is all yours.

Dave


word

even how the trail and f-c are created on the front end could vary...you could end up with 50mm of trail and a 58.5 f-c on a two different 58cm bikes -- one with a 75 hta and one with a 70 and one with a 73, depending on the TT length...its all so out of context as to be meaningless, but if the back end of all three bikes was identical and traditional for a race bike, doof suspects that one of them would ride ok and the other two would be wack....

[e-RICHIE]

This is all so confusing to me. Would any reasonable person pick a new frame based on purely on BB drop, or chainstay length, or fork rake, or etc?

As E.R. has said so many times you can't take any given spec out of the context of the complete design. One or two or three numbers alone won't make or break a design but it's how all the numbers work together that matters.

For many years Merckx didn't list head tube angles or fork rakes on thier spreads sheets. It's easy to understand his motivation if folks are picking thier new bike by a single number.

The soapbox is all yours.

Dave

since my text is snipped, i'm not sure this is
for me or at me, but i fully agree with you.
i believe consumers buy based on corporate
culture and a certain emotional attachment to
the brand and the manufacturer. specs, be damed;
these are just something to bandy about, not unlike
baseball stats.
i barely understand the science and mechanics behind
all the tech talk going on here, but repetition has a way
of being a decent teacher.
i'm comfortable choosing what goes where, being able
to measure it precisely, and improving on it as the years
tick by atmo.

[jl123]

Dave,
"This is all so confusing to me. Would any reasonable person pick a new frame based on purely on BB drop, or chainstay length, or fork rake, or etc?

As E.R. has said so many times you can't take any given spec out of the context of the complete design. One or two or three numbers alone won't make or break a design but it's how all the numbers work together that matters.

For many years Merckx didn't list head tube angles or fork rakes on thier spreads sheets. It's easy to understand his motivation if folks are picking thier new bike by a single number."

I think the majority of this thead had become confused. The major idea here is that I believe that Jan and others believe like you say that one cannot pick a new frame not purely "on drop, chainstay length and fork rake", but instead they believe in the re-discovery of many of the very well designed bikes from France in the 40 and 50's most which have similar geos. And what both Jan and Mr. Weigle have found is that the geometries of these frames work spectactually well for long distance riding.

Jan, Mr. Weigle and Matthew and others believe there can yet be more subtle tweaking to these geos, to slightly alter the handling toward added agility and especially changes necessary for weighted rack vs un-weighted front-end riding. Many people here believe the process of tweaking of any these older french geos is very difficulty. There is some debate over the accuracy needed in order to sucessfully test such changes. And I also gather there is some debate wether tweaking these older French geos is a good thing to do what-so-ever, as such changes might change the totality of the design and fuction. I personally believe such tweaks are all great experiements that even if not perfectly measured to the millimeter, but rather measured through people like Jan and Mr. Weigles riding skill is good enough. I believe that indeed if someone were to donate expensive measuring equipment to Jan the perfect measurments provided would not change his riding impressions. I think this was born out in the test of Weigles bike as tested in VBQ where Weigle was able to use Jan measuremnts on a 54' singer to interpret his newer age version. I believe the comparison of the Weigle and Singer bears this out. JL

[e-RICHIE]

And what both Jan and Mr. Weigle have found is that the geometries of these frames work spectactually well for long distance riding.
agreed. no one has taken issue with this.



I personally believe such tweaks are all great experiements that even if not perfectly measured to the millimeter, but rather measured through people like Jan and Mr. Weigles riding skill is good enough. I believe that indeed if someone were to donate expensive measuring equipment to Jan the perfect measurments provided would not change his riding impressions.

measuring is fine. using people's emotions as
a subjective opinions is fine. writing down the
results is fine.

if you opine, and then draw up graphs and/or
comparisons using numbers taken inaccurately,
and - worse yet, folks' notions turn on those very
numbers, that is when a thread like this evolves
into what it has become. a tolerance of 3mm+- and
the word accurate do not belong in the same sentence.

i don't think anyone here ever debated the riding
impressions of the writers. it was the inaccuracy of
the number-taking that was at the core of much of
this discussion.

lastly - two things: you don't need expensive measuring
equipment to measure accurately imo, and afaik, there
is no such animal as a fork assembled rearward so that
the rake yields less than the offset of the blades themselves.

[cpg]

Rivendell also has their latest fork crowns designed so that the blades are offset backwards. On their bikes, it's totally obvious, because the centerline of the fork blades is about 7 mm behind the centerline of the steerer. So you get a fork with a lot of rake, but less offset.

I have no bones to pick - it doesn't matter to me which bikes ride best. Most people used to assume that "more trail = more stable bike", and so did I. But when I was riding modern "relaxed geometry" bikes for tests in VBQ, and found that especially with a handlebar bag, they lacked the stability of my older machines, I started measuring the old bikes to see how they were different. And the results were surprising, to say the least.

Finally, all of you are welcome to submit your concerns, criticisms, comments, etc., to VBQ.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com


Sorry for being late to this. To attempt to clarify, what Jan is talking about with regard to Rivendell crowns is actually an optical illusion. The centerline of the blades is still on the centerline of the steerer. The overall shape just creates the illusion that it's behind centerline. So the fork blades are not raked any more than the offset. This is not to diminish Jan's articles. They have merit and should not be dismissed so quickly. Why are people threatened by this? I know E-richie, dbrk and a few others aren't but look at the thread count and all the non-framebuilding experts spouting how it can't work. It does work but most of the nay sayers are only looking at the issue through racing bike geometries. These designs that Jan writes about are not in relation to modern racing bikes. These are different bikes riden under different conditions. Not better or worse conditions. Just different. I don't agree with all that Jan writes but nobody should. Just like you shouldn't agree with everything that I write. But unless you actually have experience with this I wouldn't be so quick to dismiss this.

Curt

[jl123]

E-rich:
"folks' notions turn on those very
numbers"

I agree indeed that folks should not turn on such numbers ( although as I have said I think in the case of Jan and Mr. Weigle's experiements their slightly inaccurate measurements are good enough for me, but of course can stand and should be made more accurate ) but this folk does turn on their riding impressions. I will be purchasing a frame with very similar geometry, and further, I am sorry if it offends you, but this is my belief, I do not believe your *preimise that folks (readers) notions are turing on those very numbers. I believe folks take the best of what Jan is doing, next they buy into (that is agree to its overall merit) the idea, and next try those designs out for themselves, as many consumers and framebuilders are now doing for themselves. JL

[e-RICHIE]

...I am sorry if it offends you, but this is my belief, I do not believe your *preimise that folks (readers) notions are turing on those very numbers. I believe folks take the best of what Jan is doing, next they buy into (that is agree to its overall merit) the idea, and next try those designs out for themselves, as many consumers and framebuilders are now doing for themselves. JL

sorry -
i misunderstood the original post. (http://forums.thepaceline.net/showpost.php?p=203576&postcount=1)
i could have sworn the OP liked what he read,
liked what he had, and wondered why more like
this did not exist. maybe what confused me was
his follow-up; (http://forums.thepaceline.net/showpost.php?p=203993&postcount=54) i thought he was revising the (his)
original intent of summoning up the published data.


bad reading and retention skills on my part atmo.

[Grant McLean]

For many years Merckx didn't list head tube angles or fork rakes on thier spreads sheets.
Dave

Good point David,

Anyone else come across these Colango charts before?

http://www.colnagonews.com/prova2/storia/geometrie/giannimotta.php

g

[e-RICHIE]

Good point David,

Anyone else come across these Colango charts before?

http://www.colnagonews.com/prova2/storia/geometrie/giannimotta.php

g


hmmm.
frame height, length, setback, rear stays, FC©™®...
i wonder what these cats know.

[goonster]

if you opine, and then draw up graphs and/or
comparisons using numbers taken inaccurately,
and - worse yet, folks' notions turn on those very
numbers, that is when a thread like this evolves
into what it has become. a tolerance of 3mm+- and
the word accurate do not belong in the same sentence.


This whole business regarding the measurements is a red herring.

Jan has published accuracy ranges and, if anything, that gives me more, not less, confidence in his numbers. In the article I quoted above, he listed different accuracy values for different bikes. That distinguishes the work of someone who has a firm grasp of the meaning of those numbers.

As everyone knows, if you list a tolerance of +- 3 mm, the probabilities of the measurement being spot-on or off by 3 mm are not equal. Also, the individual frame dimensions do not exist indepedent of each other. When you assemble all of the measured values and review the data as a whole, a gross error in an individual value would become apparent. No?

Regardless of anyone's opinion regarding frame design, regardless of whether any particular frame dimension should be isolated and discussed, and regardless of what one may think of his methods, Jan can either measure frames or he can't. In the absence of evidence to the contrary, his experiences of measuring frames "blind" and having the results match the builders' spec sheets to a reasonable degree of accuracy seem to indicate that he can.

(edit: grammar)

[e-RICHIE]

This whole business regarding the measurements is a red herring.

Jan has published accuracy ranges and, if anything, that gives me more, not less, confidence in his numbers. In the article I quoted above, he listed different accuracy values for different bikes. That distinguishes the work of someone who has a firm grasp of the meaning of those numbers.

As everyone knows, if you list a tolerance of +- 3 mm, the probabilities of the measurement being spot-on or off by 3 mm are not equal. Also, the individual frame dimensions do not exist indepedent of each other. When you assemble all of the measured values and reviewed the data as a whole, a gross error in an individual value would become apparent. No?

how can you measure something and
be off by up to 3mm and use the term
accurate in the same breath?

i'm not debating anyone's likes or experiences
at all. we like what we like. we know what we
know. the zine has patterned itself after an
academic revue publication, one in which data
is under continuous peer scrutiny. this is not
about emotion, it's about facts, details, and
compiling data. that is where the thread went after
you (i believe it was you) introduced the publisher's
statement wrt accuracy tolerances.

[Dr. Doofus]

hmmm.
frame height, length, setback, rear stays, FC©™®...
i wonder what these cats know.


ok...doof will come clean. he took a welding class last summer cause he thought he wanted to learn how to make bike frames. what he discovered was that he was a butcher with a torch, that brazing was nowhere in his future, and that the more he read about frames the less he knew.

but

when e-ritchie says that height, setback, rear center, front center are the four crucial starting points...ignorant doof says he sho nuff is right...all the stuff on geo charts are resultants, not starting points...

the failed sorcerer's apprentice says that trail is the last point to dial in, and not a point to experiment with cause the totality has already been built...leave it as it is...one reason modern bikes are quasi-effed up is that crabon forks have made rake and trail starting points...the frame designed around the fork rather than the fork around the frame atmo....

[sspielman]

how can you measure something and
be off by up to 3mm and use the term
accurate in the same breath?

i'm not debating anyone's likes or experiences
at all. we like what we like. we know what we
know. the zine has patterned itself after an
academic revue publication, one in which data
is under continuous peer scrutiny. this is not
about emotion, it's about facts, details, and
compiling data. that is where the thread went after
you (i believe it was you) introduced the publisher's
statement wrt accuracy tolerances.


I hope that my next frame is built to an accuracy of 3 mm or less

[David Kirk]

[QUOTE=Dr. Doofus]ok...doof will come clean. he took a welding class last summer cause he thought he wanted to learn how to make bike frames. what he discovered was that he was a butcher with a torch, that brazing was nowhere in his future, and that the more he read about frames the less he knew.

That's why they invented epoxy!

Dave

[Dr. Doofus]

[QUOTE=Dr. Doofus]ok...doof will come clean. he took a welding class last summer cause he thought he wanted to learn how to make bike frames. what he discovered was that he was a butcher with a torch, that brazing was nowhere in his future, and that the more he read about frames the less he knew.

That's why they invented epoxy!

Dave

duct tape and bondo, bro

[Fixed]

[QUOTE=Dr. Doofus]ok...doof will come clean. he took a welding class last summer cause he thought he wanted to learn how to make bike frames. what he discovered was that he was a butcher with a torch, that brazing was nowhere in his future, and that the more he read about frames the less he knew.

That's why they invented epoxy!

Dave
bro old world crafsmanship is going to be lost i.m.h.o. everybody wants it now . except for a few bros . my dad was a weilder a man told me one time he was one of the best in town . he was a machinest too . a great man I miss him everyday . he could do everything . I think that is one reason i love steel lugged frames . cos a man like my dad made them . cheers

[News Man]

how can you measure something and
be off by up to 3mm and use the term
accurate in the same breath?

i'm not debating anyone's likes or experiences
at all. we like what we like. we know what we
know. the zine has patterned itself after an
academic revue publication, one in which data
is under continuous peer scrutiny. this is not
about emotion, it's about facts, details, and
compiling data. that is where the thread went after
you (i believe it was you) introduced the publisher's
statement wrt accuracy tolerances.

By trade, I am a physicist and I must admit that I did regard the article as similar in style to many academic publications. Based on what I read, I was perfectly prepared to search out my next bicycle by trail alone, and I was going after a low trail because I really thought the handling characteristics ascribed to low trail fit my style of riding. I now know that would have been a big mistake. The fact remains that the Weigle has all the handling characteristics (in my mind, and it may all be in my mind, but that counts) as the low trail offerings reviewed by Jan, but in fact it has a trail of 60 which places it as a high trail bike. There is no science here and perhaps none was intended. I thought I had something special and a good explanation to go with it and as a scientist, that was satisfying. I was right on one account, it is a special bike.

I am not sure where 3mm entered this thread, but I would rather work with a builder that considers this important than one who doesn't.

The kind of passion shown on this thread makes me happy that I am a bike enthusiast and that this forum exists.

[jan heine]

Grant,

The Colnago drawings are interesting. We have three frames that aren't that different in size - 57 through 60 cm. The numbers on the drawing are for seat and top tube lengths, setback, front-center, chainstay length and BB height. Of those, chainstay length and BB height are pretty constant. Seat and top tube lengths vary according to the rider's body measurements. Setback varies quite a bit, too, perhaps due to rider preference? But the value that varies most is front-center, by a whopping 31 mm (more than on those Kogswell prototypes.

Clearly, the Colnagos weren't designed to keep front-center constant. Basically, the front-center varies roughly as much as the top tube length ahead of the BB, so it appears to be the resultant of the rest of the frame design. Unless there is a reason why taller riders should have a much longer front-center...

In fact, looking at the numbers, I estimate that head angle and fork offset (and thus trail) of the three bikes are relatively constant - much more so than front-center. (Curt, can you plug the numbers into your CAD software and give us the accurate numbers?)

To me, it looks as if they started designing the bikes at the constant front end (head angle and fork offset as the starting point). Then they added the top tube length, subtracted the setback and thus found the BB location. They moved the top tube up or down to get the correct seat tube height. Chain stay length again is constant, and the seatstays fall where they connect the seat lug with the rear dropouts.

I don't see any other way these numbers can make sense. So even if trail (or head angle and fork offset, which is the same) isn't specified, it's one of the starting points. Just like wheel size, there is no need to spec it, because it's a given.

I am sure they then looked over the bike's design and tweaked the numbers a bit here and there to get a good overall "gestalt" - any good builder would do that. (I am the last to claim that trail is the only thing that determines how a bike handles!)

Anyhow, those Colnagos are interesting. I haven't ridden any of the bikes in question, so I am willing to accept that Colnago had no clue, and that Merckx et al. would have been better off on a Sachs...

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[jan heine]

The fact remains that the Weigle has all the handling characteristics (in my mind, and it may all be in my mind, but that counts) as the low trail offerings reviewed by Jan, but in fact it has a trail of 60 which places it as a high trail bike.

Peter Weigle modified his geometries in recent years. The bike we rode was one of the first "low-trail" Weigles. I have ridden one of Weigle's older bikes. While pleasant, it rode very differently, and I prefer the newer one. I would not discount Weigle as a builder only because he is willing to experiment and modify his products when he finds something that works even better than his previous bikes.

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[goonster]

I am not sure where 3mm entered this thread, but I would rather work with a builder that considers this important than one who doesn't.

It entered the thread because I quoted the accuracy figure as published by VBQ for a particular bike.

Certainly 3 mm is significant when building a bike.

When measuring an existing bike, for the purpose of discussing its geometry, an accuracy of +- 3 mm for an individual measurement (where the probability of that measurement being off by 3 mm is, what, 5%?), that accuracy is good enough for me.

how can you measure something and
be off by up to 3mm and use the term
accurate in the same breath?


For someone who preaches Gestalt-itis, embracing the wholeness of an endeavour, you seem awfully hung up on this 3 mm number. ;)

How about everyone who thinks Jan can't measure a bike chips in, e-Richie builds him a frame, and if Jan gets the measurements right he gets to keep it? :p

[whippettanker]

I hope that my next frame is built to an accuracy of 3 mm or less

I hope my next frame rides well.

[News Man]

I would not discount Weigle as a builder only because he is willing to experiment and modify his products when he finds something that works even better than his previous bikes.



I am not sure what this means. Who is discounting Weigle here?

[Dr. Doofus]

Clearly, the Colnagos weren't designed to keep front-center constant. Basically, the front-center varies roughly as much as the top tube length ahead of the BB, so it appears to be the resultant of the rest of the frame design. Unless there is a reason why taller riders should have a much longer front-center...

In fact, looking at the numbers, I estimate that head angle and fork offset (and thus trail) of the three bikes are relatively constant - much more so than front-center. (Curt, can you plug the numbers into your CAD software and give us the accurate numbers?)

To me, it looks as if they started designing the bikes at the constant front end (head angle and fork offset as the starting point). Then they added the top tube length, subtracted the setback and thus found the BB location. They moved the top tube up or down to get the correct seat tube height. Chain stay length again is constant, and the seatstays fall where they connect the seat lug with the rear dropouts.

I don't see any other way these numbers can make sense. So even if trail (or head angle and fork offset, which is the same) isn't specified, it's one of the starting points. Just like wheel size, there is no need to spec it, because it's a given.

I am sure they then looked over the bike's design and tweaked the numbers a bit here and there to get a good overall "gestalt" - any good builder would do that. (I am the last to claim that trail is the only thing that determines how a bike handles!)

Anyhow, those Colnagos are interesting. I haven't ridden any of the bikes in question, so I am willing to accept that Colnago had no clue, and that Merckx et al. would have been better off on a Sachs...

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com


functioning at the limits of my doofusdepth on this topic:

yes, taller riders would need a longer f-c: because their hands are farther out...taller rider=longer arms, longer stem, longer tt.... the longer f-c is a starting point to put the wheel in an optimum relationship to the front-end contact point.

these frames were built around contact points -- frame setback puts the riders butt where it needs to be, f-c puts the hands where they need to be with an appropriate length stem, chainstay length finishes off the weight distribution picture. also, one suspects that bb location was a starting point for solving the weight distribution problem, not a result of solving the problem -- frame setback extends back from that starting point to arrange (disorderly) rider weight over the rear wheel. the bb is the CoG point to start spreading the weight out from (did doof get that right in the foolishly self-guided frame-design crash course, ER?).

doof doubts that ernesto started with a set front end and moved it out based on rider measurements...he probably started with the measurements or the contact points, saw where the hands needed to be, then arrived at the f-c, then chose the hta/fork rake as the best way to achieve desired handling characteristics over the roads the rider had to deal with.

a bike is a platform for weight distribution, albeit a platorm that has to roll and lean over a given set of surfaces at a given range of speeds. doof bets colnago looked at the contact points, considered the types of surfaces the rider would encounter, the speeds at which the platform/vehicle would have to function, and then arrived at the f-c, r-c, setback, and height....

EC probably used the same design process as ER. ER would find a *slightly* different set of solutions to the weight distribution problem because US roads in 2006 are a heck of a lot better than euro roads in 1970. but ER and EC are basically smokin from the same bowl.


(bear in mind doof is not a bike builder, therefore by his own definition has nothing meaningful to say about bike design)

[whippettanker]

hmmm.
frame height, length, setback, rear stays, FC©™®...
i wonder what these cats know.


Where do you see the setback?

[palincss]

The fact remains that the Weigle has all the handling characteristics (in my mind, and it may all be in my mind, but that counts) as the low trail offerings reviewed by Jan, but in fact it has a trail of 60 which places it as a high trail bike. There is no science here and perhaps none was intended. I thought I had something special and a good explanation to go with it and as a scientist, that was satisfying. I was right on one account, it is a special bike.


Which Weigle are we talking about here? One you own, or the one tested in a recent VBQ issue?

[e-RICHIE]

Where do you see the setback?


the number above the seat lug area...
17.5, 16.5, 15...

[News Man]

Which Weigle are we talking about here? One you own, or the one tested in a recent VBQ issue?

One I own, of course.

[whippettanker]

the number above the seat lug area...
17.5, 16.5, 15...

Ah

I was thinking that they might be S/T angles

(90-16.5) = 73.5
(90-17.5) = 72.5
etc...

But smaller frames on the Colnago site have
smaller values so they must be setbacks.

So that's arcCosine(seattube/setback) = S/T angle

[e-RICHIE]

So since all other dimensions are reported as
lengths, then you think these are lengths
as well?

I'm just wondering why they aren't S/T angles?

(90-16.5) = 73.5
(90-17.5) = 72.5
etc...

they're linear.
why are you perservating on this yo?

[Grant McLean]

Grant,

The Colnago drawings are interesting. We have three frames that aren't that different in size - 57 through 60 cm. The numbers on the drawing are for seat and top tube lengths, setback, front-center, chainstay length and BB height. Of those, chainstay length and BB height are pretty constant. Seat and top tube lengths vary according to the rider's body measurements. Setback varies quite a bit, too, perhaps due to rider preference? But the value that varies most is front-center, by a whopping 31 mm (more than on those Kogswell prototypes.

Clearly, the Colnagos weren't designed to keep front-center constant. Basically, the front-center varies roughly as much as the top tube length ahead of the BB, so it appears to be the resultant of the rest of the frame design. Unless there is a reason why taller riders should have a much longer front-center...
www.vintagebicyclepress.com

Hi Jan,

thanks for taking the time to look at the charts.
I profess to know nothing about "why" framebuilders do anything.

The only thing I offer from my 26 years of searching for nice riding bikes,
is that changing front center length profoundly changes how a bike handles.

I in NO way am saying that every bike out there should have the
same front center. There is no magic front center measurement that
works for every size, shape, and type of rider.

It's totally dependant on the specific rider, and the use of the bike.

Take one rider example:
If you look at the charts for eddy merckx: there are seven of them.

http://www.colnagonews.com/prova2/storia/geometrie/merckx.php

Six have the same front center, even though the top tube ranges from 54.5 - 58.
Top Tube / Front Center
54.5 / 60.8
58 / 60
56.5 / 60
58.5 / 60
54.5 / 60
57.5 / 60
54.5 / 60

Seems to me that Eddy liked a 60cm front center, regardless of what the
top tube is, the constant for Eddy is 60.

Are you searching for 1 magic front center number that works for every bike?
It doesn't exsist, in fact, the OPPOSITE is true. Every rider of a different
size will require a different front center.



-g

[e-RICHIE]

these frames were built around contact points -- frame setback puts the riders butt where it needs to be, f-c puts the hands where they need to be with an appropriate length stem, chainstay length finishes off the weight distribution picture. also, Ione suspects that bb location was a starting point -- frame setback extends back from that point to arrange (disorderly) rider weight over the rear wheel. the bb is the CoG point to start spreading the weight out from.


a bike is a platform for weight distribution...



i agree with doof.
set up rider's leg extention = frame height and setback.
set up rider's reach = top tube, stem sized approiately for bike size, and head angle (from which telescopes the h'bar assembly).
set up rider's balance points above and between wheels = front center and rear stays.

a builder knows the range for angle/trail/fork rake that will allow for all
the above to occur. he uses that range to balance a rider on a bicycle.
when you're on the inside, you sooner or later realize that the common
factoids that are perpetuated by the comsumer press (not vbq) about
how 73=road and 72=touring and 74=aggressive crit, etcetera are
meaningless once you're cutting metal and solving problems.

[e-RICHIE]

I'm thinking that these are jig setups.

Facinating.


fascinating atmo

[whippettanker]

they're linear.
why are you perservating on this yo?

be prepared, that's my motto

[e-RICHIE]

be prepared, that's my motto
The Frame is the Frame ©™®

[jan heine]

Six have the same front center, even though the top tube ranges from 54.5 - 58.
-g

I don't think Merckx ever rode a top tube as short as 54.5 cm. He already used long stems with a 58.5 cm top tube (12.5 cm according to drawing No. 4)). So he'd need a 16.5 cm stem to keep his reach constant with a 54.5 cm top tube! I don't think Cinelli even made stems that long in the 1970s. (I know that your reach depends on a lot of factors, including handlebars, and that Merckx' back injury might have affected his reach, but not by that much.)

The first bike on the site you quote has a 57.5 top tube, and the 54.5 you took for the top tube length is some other "mystery" number. I think the last bike's top tube number is again that other "mystery" number, and it was just entered in the wrong place. So Merckx' top tube varied between 57.5 and 58.5 cm, which makes it a lot easier to keep his front-center constant.

In my 20 years of serious riding, racing and randonneuring, almost every measurement on my bikes has changed. Only one has stayed the same: top tube length. That one has gone up by 5 mm, and the stem length hasn't changed at all. I ride bikes with different measurements, and they are fine, but I still prefer bikes that fit perfectly.

BTW, what is that other "mystery" number that is so easily mistaken for top tube length?

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

[e-RICHIE]

BTW, what is that other "mystery" number that is so easily mistaken for top tube length?

it's more than likely the cut length;
cuy length typically is/was 2.8-3cm
less than desired yield length.

some of these charts have arcane info,
such as the notation of 58.5 on this:
http://www.colnagonews.com/prova2/storia/geometrie/roger.php
it shows the working down tube angle
needed to yield the resultant head angle
and fron center on that particular bicycle,
assuming 1) the top tube was level and,
2) the fork length was built to the prescribed
design. in those days in those shops, the
down tube/head tube confluence was fixtured
first, as a subassembly, and then used to
construct a main triangle around.

[Grant McLean]

I don't think Merckx ever rode a top tube as short as 54.5 cm. He already used long stems with a 58.5 cm top tube (12.5 cm according to drawing No. 4)). So he'd need a 16.5 cm stem to keep his reach constant with a 54.5 cm top tube! I don't think Cinelli even made stems that long in the 1970s. (I know that your reach depends on a lot of factors, including handlebars, and that Merckx' back injury might have affected his reach, but not by that much.)

The first bike on the site you quote has a 57.5 top tube, and the 54.5 you took for the top tube length is some other "mystery" number. I think the last bike's top tube number is again that other "mystery" number, and it was just entered in the wrong place. So Merckx' top tube varied between 57.5 and 58.5 cm, which makes it a lot easier to keep his front-center constant.

In my 20 years of serious riding, racing and randonneuring, almost every measurement on my bikes has changed. Only one has stayed the same: top tube length. That one has gone up by 5 mm, and the stem length hasn't changed at all. I ride bikes with different measurements, and they are fine, but I still prefer bikes that fit perfectly.

BTW, what is that other "mystery" number that is so easily mistaken for top tube length?

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

Jan,

Why are you assuming his reach stayed constant?
I figured Eddy asked for different frames to be built BECAUSE he wanted
different reach, (back problems). The ONE constant is Front Center.

As for top tube: Depending on the seat tube angle, the top tube length
doesn't directly correspond with "reach". Drop a plumb line to the
bb and measure forward, every part of the top tube behind that point
doesn't matter for fit. If every bike has the same seat tube angle,
the top tube would be the same, but if the angle changes, the length
of the top tube should too.

Doofus and Richie already said it: postion cleats, then saddle set back, and
height, postion hands, and fill in the wheels with the right spacing.
Easy peasy.


g

[jerk]

Grant,

The Colnago drawings are interesting. We have three frames that aren't that different in size - 57 through 60 cm. The numbers on the drawing are for seat and top tube lengths, setback, front-center, chainstay length and BB height. Of those, chainstay length and BB height are pretty constant. Seat and top tube lengths vary according to the rider's body measurements. Setback varies quite a bit, too, perhaps due to rider preference? But the value that varies most is front-center, by a whopping 31 mm (more than on those Kogswell prototypes.

Clearly, the Colnagos weren't designed to keep front-center constant. Basically, the front-center varies roughly as much as the top tube length ahead of the BB, so it appears to be the resultant of the rest of the frame design. Unless there is a reason why taller riders should have a much longer front-center...

In fact, looking at the numbers, I estimate that head angle and fork offset (and thus trail) of the three bikes are relatively constant - much more so than front-center. (Curt, can you plug the numbers into your CAD software and give us the accurate numbers?)

To me, it looks as if they started designing the bikes at the constant front end (head angle and fork offset as the starting point). Then they added the top tube length, subtracted the setback and thus found the BB location. They moved the top tube up or down to get the correct seat tube height. Chain stay length again is constant, and the seatstays fall where they connect the seat lug with the rear dropouts.

I don't see any other way these numbers can make sense. So even if trail (or head angle and fork offset, which is the same) isn't specified, it's one of the starting points. Just like wheel size, there is no need to spec it, because it's a given.

I am sure they then looked over the bike's design and tweaked the numbers a bit here and there to get a good overall "gestalt" - any good builder would do that. (I am the last to claim that trail is the only thing that determines how a bike handles!)

Anyhow, those Colnagos are interesting. I haven't ridden any of the bikes in question, so I am willing to accept that Colnago had no clue, and that Merckx et al. would have been better off on a Sachs...

Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
www.vintagebicyclepress.com

go ride one. colnago knows exactly what he is doing. the resulting bicycle from those measurements ride very well, better than just about everything else out there. they like weight on the front wheel and as they get "bigger" without starting to behave like different bikes in different sizes.

colnago has more of a clue than you do. plus he was able to cut his costs by utilizing a single fork offset.

go ride a c50.

jerk

[jerk]

top tube lengths are the result of achieving front center, bb drop, head angle and set back! as a measurement it means nothing! (sort of like "trail" really.) that's why top tube lengths are always strange sizes in properly designed bikes.

jerk

[e-RICHIE]

top tube lengths are the result of achieving front center, bb drop, head angle and set back! as a measurement it means nothing! (sort of like "trail" really.) that's why top tube lengths are always strange sizes in properly designed bikes.

jerk

correct -
the space is more important than the actual
tube length spec. how parts telescope out of
head and seat tubes has a strange way of skewing
the reach dimensions of similarly sized top tubes.
the angles dictate where in space parts end up.

[whippettanker]

plus he was able to cut his costs by utilizing a single fork offset.


See in the real world it costs less to make a fork than a frame... so multiple offsets was rational and economical.

[e-RICHIE]

See in the real world it costs less to make a fork than a frame... so multiple offsets was rational and economical.

why not make compact P/Rs?
3 sizes fits most atmo.

[catulle]

Ehem, excuse me but, what's front center? Thank you. :confused:

[Grant McLean]

Ehem, excuse me but, what's front center? Thank you. :confused:

It's the place in hell specifically reserved for all the smarty-pants.

;)

g

[catulle]

It's the place in hell specifically reserved for all the smarty-pants.

;)

g

Er, no, really, front center doesn't fall within my circle of light. I know about flux, praxis, and the polimorphous pervert, but I don't know what is front center, iirc, atmo.

[e-RICHIE]

Er, no, really, front center doesn't fall within my circle of light. I know about flux, praxis, and the polimorphous pervert, but I don't know what is front center, iirc, atmo.



FC©™®

[jerk]

Er, no, really, front center doesn't fall within my circle of light. I know about flux, praxis, and the polimorphous pervert, but I don't know what is front center, iirc, atmo.


it's the primary reason why the jerk put you on the right sized colnago and the one you got it too big.

jerk

[catulle]

Would someone please point their little finger to the front center part of this frame, pretty please, atmo.

[manet]

quote: "The Gaansari had the fork blades offset a few mm to the rear, not enough to be apparent immediately."


are we talking about bent-back blades(?!) _ please no!
if there is a hell this will be employee of the month for a year.

[whippettanker]

Would someone please point their little finger to the front center part of this frame, pretty please, atmo.

http://kogswell.com/images/fc.gif

Front center (or FC©™® as it is known in some circles) is the dimension shown above.

It's the distance from the front axle center to the bottom bracket center.

The bottom bracket is the origin for lots of frame(set) dimensions.

Hope this helps.

Matthew Grimm / Whippet Tanker
Kogswell Cycles

[catulle]

Thank you....!!!

[Johny]

Thank you....!!!

Because MG turned your Colnago C-50 into a Kogswell?

[catulle]

Because MG turned your Colnago C-50 into a Kogswell?

Nope, just because he expanded the circle of light of my lantern, atmo.

[e-RICHIE]

Nope, just because he expanded the circle of light of my lantern, atmo.

the light is over-rated.
you want the heat atmo.

[manet]

the light is over-rated.
you want the heat atmo.

http://i37.photobucket.com/albums/e61/easterncaster/IMG_0088.jpg