Lightweight Frame Tubing and "Planing" [Archive]

eddief

10-01-2017, 07:20 PM

is tough to design into a bike...in my opinion. You happen into it or luck into it cuz it is a magical phenomenon. I think a builder can set you in the right direction for sure and plump low pressure tires are a giant step in the right direction, but no builder will tell you he can design planing into the build. As much about tires as metal tubes, especially with weight hanging from the bike.

I swear my el cheapo modern Fuji Touring was a planer.

https://www.performancebike.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10052&langId=-1&catalogId=10551&productId=7000000000000008823&utm_source=Google_Product_Search&utm_medium=pla&utm_campaign=datafeed&cm_mmc=Google_Product_Search-_-PLA-_-Datafeed-_-Fuji%20Touring%20Road%20Bike%20-%202018%20Black%2058&CAWELAID=400006950000200697&CAGPSPN=pla&CAAGID=25577014563&CATCI=aud-322945453344:pla-157198229283&catargetid=400006950000108166&cadevice=c&gclid=Cj0KCQjwx8fOBRD7ARIsAPVq-Nn4JoQi0Nkh_xjhIMvUEKTNGHBeCMKyhNE-GAAcMo1fcEWWgUgPUGQaAmiHEALw_wcB

Custom-butted Elios 2 chromoly frame with rack and fender mounts
Elios 2 Chromoly fork features low-rider rack mounts

ultraman6970

10-01-2017, 07:59 PM

Paper thin tubes and rando is not like a combination I would recommend for anybody. Specially if you want the frame to last you for a very long time.

adampaiva

10-01-2017, 11:34 PM

I'm about 15 lbs heavier than you and put my bikes through a lot. I have a Lyon L'Avecaise with the BQ formula tubing (and 650b) and it does plane, or I think so anyway. I rode it for 40 miles today about half on mountain bike trails and half on gravel and dirt carriage roads. I hit a surprise rock and went over the handlebars. I went down a rocky rooty descent at 30 mph. I bunny hop off the occasional rock and curb. So far, the bike has held up to all the abuse with nothing to show of it. (Touch wood)

I'm curious if there's any hesitation from builders on the Toei fork blades (I have them) and using low rider panniers.

buddybikes

10-02-2017, 05:47 AM

We obtained a abosolutely great Bilenky tandem made from super thin aerolite tubing in the 1990's. bike has long since put away due to back issues - examined it, there is a rust hole in the rear seattube. thin stuff - between denting an rusting do you really want that kind of concerns?

Peter P.

10-02-2017, 06:10 AM

Some explain planing to me, please!

eddief

10-02-2017, 06:15 AM

https://janheine.wordpress.com/2014/11/23/what-is-planing/

https://janheine.wordpress.com/2014/12/31/the-biomechanics-of-planing/

ripvanrando

10-02-2017, 06:22 AM

Paper thin tubes and rando is not like a combination I would recommend for anybody. Specially if you want the frame to last you for a very long time.

Or barely controllable shimmy.

etu

10-02-2017, 07:07 AM

I love the handling of the low trail fork on my commuter. Planning is a bit more of a complicated phenomenon but I think most people will agree that frame flex is important to the ride quality, along with a few other factors. Question is how much flex is too much or not enough. It's really subjective. Even in Jan Heine's double blinded experiment, one of the rider's couldn't tell the difference. This tells me the .7-.4.-.7 is a good starting point, but not necessarily the best for everyone. I would think a good frame builder can give you the best chance to get the ideal build. Regardless it's still a best guess. I'd say go for it and see how it goes. Chances are that you'll really like your new bike. Whether it will be the holy grail you seek... you'll never know until you ride it for a while.

palincss

10-02-2017, 08:45 AM

Hey all, this came up in another thread and I didn't want to go too off topic so I'm starting a new one. I'm looking into a new custom, low trail, 650b randonneur and from reading the reviews of bikes in Bicycle Quarterly, I've become interested in lightweight tubing and what the BQ folks call planing. I weigh between 160 and 170 depending on the season and am more of a spinner. My question is if folks seem to think that lightweight tube specs such as .7-.4-.7 tubes and Kasei fork blades would be too light of a spec for a rider like me on that type of a bike? The bike will typically carry a 10-15 lb loads with the occasional 30-40 more pounds on the fork on lowriders for the weekend camping trip, light touring, etc. Any insights y'all can offer would be greatly appreciated! Framebuilder's insights would be particularly appreciated :)

I think you're about the same weight as Jan Heine. You've read BQ, you know about the bikes he rides and the way he does it. You're basically describing his Mule.

false_Aest

10-02-2017, 08:51 AM

I'm not 100% sure that thin-walled tubing makes a flexier bike (if you're using hi-grade tubing and not hiten crap)

About 2 years ago I got to test out two bikes with the same geo + same tubing diameter, different wall thicknesses. They rode identically. The weight saving was about 150g. The biggest difference was how easily the thin-walled tubing dented.

Dave Kirk: "The diameter of the tubing used on a bike has much more to do with how stiff the frame will be than the wall thickness of that tube. So in Joan’s case I chose to use ‘standard’ diameter tubes to make the bike lighter and to give it the appropriate stiffness. "

http://kirkframeworks.com/2009/08/25/size-and-weight-appropriate/

----
My framebuilding experience (limited but it's there) tells me this:

Thin-walled tubing feels great in my hands; feels great when all the tubes are stuck together. As soon as I hang parts on the frame, throw a leg over the bike and point it upwards, I can't tell the difference.

You know when I can tell a difference? When my dog accidentally knocks the bike over and dents the top tube.
----

If I wanted a bike to plane I'd choose the appropriate main tubes for my riding style, carelessness and weight.

Then I'd choose wimpy chainstays, add some bends and be done with it.

cnighbor1

10-02-2017, 11:22 AM

adampaiva

10-02-2017, 11:51 AM

heh. No, separate incidents. The over the handlebars thing basically happened in slow-motion.

timto

10-02-2017, 12:14 PM

As mentioned above too - the BQ spec type bike is thin walls AND small (std) diameter tubes with stiff chain stays (typically round or ror). I've goofed around with many permutations of tube diameter and wall thickness but have yet to build with kaisei blades...

My personal observations for the BQ type frames are as such (at 160 lbs)

With front bag and weight = more prone to shimmy
Skinny tubes make the bike feel like a handful when really reefing on the bars / sprint type efforts with bigger gears
Tempo riding while staying on top of the gear does feel nicer on a nice flexy bike vs a super stiff one and accelerating with leg speed vs higher gear and torque feels like flying on a super flexy bike. A nice feel.

Other observations for this genre of bike
650b @ 38mm felt like they didn't maintain their momentum as well as 700 c wheels at 38mm
Low trail handles just as nice without weight as with weight (easy to get used to)
Fenders and horizontal drop outs are too finicky (go vertical)
Lots of accessories makes for a heavy to pick up bike
If it's a dream bike consider the bag/decaleur/rack up front/lighting details up front

If I were making a bike for a power rider, someone who liked leaning on the pedals in huge gears and pulling on their bars, or who was really tall (big frame) or heavy I wouldn't use std tubing diameters and thin walls. If I were build a city beater that would get locked up to poles and stuff I wouldn't use super thin walls either.

Also I also don't believe the other claims such as more power, or less leg pain but I do know I like the feel of a flexy (within reason) frame. Feels really great. I don't race. I enjoy a more flexy bike over a stiff bike any day. So much so I've stopped looking at racy race bikes all together.
FWIW
Tim

cachagua

10-02-2017, 12:25 PM

Mr. Heine says,

Finite element analysis models have shown that almost all energy that you input into the frame as flex gets returned into the drivetrain, powering the bike. This stored energy is released when the pedal stroke approaches the dead spots.

Let's think. Your leg pushes against the bike (speaking in the abstract) and the resistance to acceleration pushes against it in the other direction, and the frame deflects from the force. Like a spring, yes. Think of your frame as a giant bobby pin, pinched between your foot and your back tire's contact patch.

Then as your leg presses a little less -- as you approach the dead spot in your stroke -- and as the force it's applying drops below the force the frame has stored, the frame unsprings and "gives back" that energy. Good so far.

And where does that energy go? Toward which side of the squeeze, as we pictured it, on the bobby pin of your frame? Does it go toward the resistance at the rear wheel, or does it go the other way?

Goes toward the side where the opposing force is lower, presumably. And the side where the force is lower is not the resistance at the rear wheel -- that has remained constant through the whole process. The side where the force is lower is your leg, which is coming around to where it can't push as hard.

Therefore I don't think you actually "get back" the energy that goes into frame flex in forward motion -- you get it back, essentially, in slowing down your legs. The energy stored in the spring of your frame can't accelerate you because there's somewhere easier for it to go. I don't deny Jan's experimental results, and I think a little twang in a bike frame can feel nice and be useful, but I don't think it's for that reason. The second half of that quote above looks right, but the first half I think has a hole in it somewhere.

Or am I not seeing this accurately at all?

Mark McM

10-02-2017, 12:31 PM

Theory and hypothesis aside about how a rider might generate more power with a flexible frame ...

If a flexible frame that "planed" could allow a rider to generate 15% more power (as claimed in the second article), than why wouldn't professional racing teams use such frames? A 15% difference in power would vault a middle-of-the-pack racer into being an untouchable winner. Heck, that's probably a bigger advantage than blood doping can provide. That kind of improvement could not be ignored, even if you wanted to for business/financial reasons. I call BS.

disspence

10-02-2017, 01:08 PM

GregL

10-02-2017, 01:18 PM

I agree. 15% more power is quite the claim. If it is true that all riders could generate 15% more power with the frame flex described, then this would be adopted by the pro peloton.
Another engineer jumping on this band wagon. The "planing" articles are glorified opinion pieces, NOT well-researched scientific studies.

Greg

El Chaba

10-02-2017, 01:46 PM

15% increase in power output?..what a load....However, I have to testify that a bike built with light gauge tubing in standard diameter can feel fantastic. I have a Peugeot (Pro 10) built in very early 1982 that is made with Reynolds 531 with 0.5 mm tubing save for the top tube which is *believed* to be 0.3 (you can squeeze it). The bike has the greatest ride characteristics, and I can fully understand why somebody would coin a term such as "planning" to describe it. Of course, there are no free lunches and you wouldn't want to have the bike fall over into the corner of a brick wall....It's also not the best bike that I have ever ridden for stomping up a short steep hill in the big ring, but you can still do it especially if you make enough grunting and heavy breathing sounds to drown out the sound of a little front derailleur rubbing...I think that light gauge tubing might a fair portion of the "magic" that is often attributed to many of the bikes built by constructeurs such as Rene Herse and Alex Singer. They really tended to go light except for the full campeur models or the ones built for tall or heavy riders.

disspence

10-02-2017, 01:58 PM

Another engineer jumping on this band wagon. The "planing" articles are glorified opinion pieces, NOT well-researched scientific studies.

Greg

You're right that Jan's posts on Off the Beaten Path should be read as opinion, and I forget that sometimes because the semblance of scientific method put forth in all the BQ tests.

bewheels

10-02-2017, 05:53 PM

As others have stated...if there was this level of untapped free power laying around all these decades it wouldn't be such a secret.

Regarding tubing thickness - I have a slightly different approach: if I am paying for the services of a highly skilled professional frame builder who's job it is to take in all the factors necessary to build a great end product for me, I have no business trying to tell them what specifications of the materials should be used. If they need me to tell, I should find a different builder.
If they let me dictate what the material specs should be, I would be very cautious.

merckx

10-02-2017, 07:35 PM

Sean Kelly planed his way to the bank on his French noodle.

bicycletricycle

10-02-2017, 10:27 PM

He claims 15%! I don't remember reading that before.

That is laughable, I like bq but opinions are not facts, it is fine to do basic unscientific/semi scientific tests but in the end the result is still mostly, "I like this one more".

As far as frame flex = mechanical reservoir thing.

It seems to me more likely that in the dead spots that stored energy in the frame is expended slowing your feet down (partially, as long as you are applying some load some will go to drivetrain?)not speeding the bike up, that is a much easier path for it to travel. (I am no engineer). If this does work why not make cranks out of leaf springs and store more energy in those to be used later?

Besides , less frame flex would just apply that power directly, sounds just as good to me.

If we could make a robot pedal a test rig we could compare frames to see if more power is getting to the wheels on the flexy ones.

I guess storing power to be released in the dead spots could reduce small pulses in acceleration which sounds like it could be more efficient. If that is what it is doing and if the losses in the "storage" are smaller than the "gains". Seems unlikely but possible I guess. Not sure if an average speed of 18 achieved by always going 18 is more efficient then micro pulsing above and below 18. I am crap at equations and physics and biomechanics and aerodynamics, etc.

As far as frame flex is suspension goes. On rock hard thin tires go for it, but why bother on a bike with nice big tires? Let the frame do its job and the tires can suspend it. Obviously it is always some of both, just more about the design priorities of each component.

Shimmy- flexy frames have more shimmy, shimmy sucks.

Obviously people like all kinds of bikes and use them and like them so who cares really I guess. It would just suck to wait two years to get a frame built to specs that you don't really like because an opinionated eccentric expert ( I fit this description as well) likes those specs.

On the other hand, I really like big smooth tires for road use now and that was largely inspired by weirdos (grant, jan)

marciero

10-03-2017, 07:03 AM

The first article cites a value of 12% for one test. To make a blanket claim this would need to be replicated by lots of tests. But nobody does this. I appreciate that BQ even does these tests. The weight to give them is up to the reader, but I consider them as evidence-beyond anecdote and opinion. Who even does double-blind tests with real riders on otherwise identical bikes? No, the tests are not perfect but keep in mind that many, perhaps most, peer-reviewed health-related studies are far from perfect in that there are often many confounding variables, they do not or cannot use randomized subjects, etc.

Not sure where the 15% blanket value in the second article was arrived at, but keep in mind that this is about "optimized" flex characteristics; that is, flex optimized to the rider, and, probably, the style of riding. Just as a weekend golfer using a flexy carbon-shafted driver can hit a ball much farther (I would guess 15%, easy) than he could with a XXX-shafted club that a pro might use, I find it conceivable that a featherweight climber might be much better off with a flexy bike than he would with a stiff bike that a sprinter might perform better with. Am pretty sure the big companies that sponsor pro riders dont do custom carbon lay-ups for each rider. At one time some of the stars did get this. Is a shame since the flex characteristics of carbon are so tune-able.

Doug Fattic

10-03-2017, 09:08 AM

There are very few frames in existence anywhere that were made with 1" top tubes with a wall thickness of .7./4/.7mm in the top and down tubes. Production frame companies avoid such tubing because it is more likely to fail (they could be ridden by someone bigger and heavier than the frame is intended to support) and thin wall heat treated tubing requires more care when building. Neither of these issues help their bottom line. I kind of remember there were some Japanese frames made in the 80’s I think that were made with thin walled tubing (maybe Shogun?) and Raleigh owned by the same company as Reynolds made some frames out of 753 tubing in the 70’s. There was a pro team that rode them. Bill Davidson had a bigger frame making operation in the 80’s and 90’s that turned out hundreds of units a year that used Tange Prestige tubing some of which was probably 7/4/7.

There are a number of custom frame builders who also avoid this tubing because of philosophy or their preference for the looks of a frame with bigger diameter tubes or they buy heavier tubing in bulk because it is cheaper and therefore more profitable. Jan began researching why his old French Herse and Singer bicycles seemed to him to have superior ride qualities. He was told that their top and down tubes were "3 tenths" - which I have understood to mean that the middle of the tubes were .3mm (3/10th) thick. This is a bit of a mystery to me because any tubing I am familiar with that has a center of .3mm, would have ends that would only be .6mm. This is very thin and would not tend to hold up under normal use like the classic old frames he loves to ride. But I digress.

Long before I ever heard of Jan Heine or when the Bicycle Quarterly was first published I have personally built frames with 1” heat treated thin wall top tubes. I vastly prefer the ride. It is what I would describe as more “lively”. It is easy for me to tell the difference between 7/4/7 and 9/6/9 when I am riding them. I can also tell the difference between thin walled 1” and 1 1/8th inch top tubes. Back in 1978 or so I built a 56 cm frame with Ishiwata 015 tubing that had top and down tube with wall thicknesses of .6/.3./.6. The whole bicycle weighted about 15 1/2 pounds and has been in the Three Oaks bicycle museum for the last 25 years or so. The ride was not too flexible for me. In fact going by memory it didn’t seem that flexible at all. However some of my bigger racing buddies thought it was. This is an illustration that what tubing wall thickness and diameter is best is based on a number of a personal preferences. The problem with 6/3/6 tubing is that it is easily damaged.

I am sorry that the hypothesis called “planing” became associated with light tubing. The problem as I see it is that it can become easy to reject the use of 7/4/7 tubing because of skepticism of the theory. I am not saying planning is wrong or right, I just know I personally very much prefer the ride of a frame made out of standard size (1” top tubes) and light tubing (.7/.4/.7mm top and down tubes). Your mileage may vary.

false_Aest

10-03-2017, 09:22 AM

Hey Doug,

I was always under the impression that tubing diameter (and shape) contributed more to stiffness than wall thickness. But in your 3rd paragraph seems to slightly contradict that -- maybe I'm misreading?

To your idea of a "lively" bike, that seems to be a bit different than what Jan is talking about. Your description makes me think of a bell or tuning fork. If a bell is made well it will sound beautiful, if it's not done right it's horrible and shrill. Seems to be a similar when building a bike ... it's gotta be tuned and a 1-size fits all doesn't work for some folks.

To your note about production thin wall bikes. You're spot on. I've worked with a few factories that refuse to do anything under 1mm straight gauge tubing (they really prefer 1.2mm) b/c they cannot guarantee that a frame will leave the factory w/out dents.

bicipunk

10-03-2017, 10:30 AM

I didn't realize how hotly debated this topic was. I'm wondering if those who are pro thin walled tubes see any downsides to riding those bikes with loads. I would imagine they would be more noodley? Standard diameter 8/5/8 might be a good place for me to start to try lighter weight tubes considering the lightest I've ridden is old reynolds 531 with 9/6/9...

Mark McM

10-03-2017, 10:40 AM

I agree. 15% more power is quite the claim. If it is true that all riders could generate 15% more power with the frame flex described, then this would be adopted by the pro peloton.

If energy stored in the frame can drive more power to the rear wheel, then energy stored in the cranks should do it even more efficiently! I just installed this cranks on my bike, and I can't wait to reap the benefits of 15+% more power!

http://pardo.net/bike/pic/mobi/d.interdrive-crank/farm7.staticflickr.com/6156/6231286452_105fa3d08a_o_d.jpg

mayal7

10-03-2017, 10:41 AM

paper thin tubes and rando is not like a combination i would recommend for anybody. Specially if you want the frame to last you for a very long time.

+1

false_Aest

10-03-2017, 10:42 AM

Standard diameter 8/5/8 might be a good place for me to start to try lighter weight tubes considering the lightest I've ridden is old reynolds 531 with 9/6/9...

If you're building this for yourself + you have time then build the same bike twice. Same tubing diameter just go with a thinner wall tube.

Really, if you have a lot of time you could build a bunch of iterations
TT 969, 858, 747
DT 969, 858, 747 (I think that's Columbus Life range)

Then on to chain stays.
Round, Round-oval-round, 30x16, 26x16, single bend, s-bend.

Seat Stays:
16-12.5 taper, 14-10.5 taper, single bend, s-bend

There's 16 combos right there! Then you could start combining the combos. Then other brands of tubing! Then joining methods: lug, fillet braze, tig, bi-lam, TIG braze, MIG, arc, etc. By the time you're done you'll have enough practice to go into business!
----

If you're not going to do this yourself don't tell the builder what to build with. Tell the builder what you're hoping for and have faith.

Telling a builder what to do is like having a seamstress tell a luthier what wood to choose for her uncle's cousin's friend's sister's guitar.

bicipunk

10-03-2017, 11:04 AM

If you're not going to do this yourself don't tell the builder what to build with. Tell the builder what you're hoping for and have faith.

Telling a builder what to do is like having a seamstress tell a luthier what wood to choose for her uncle's cousin's friend's sister's guitar.

I hear ya on that. I certainly wouldn't dream of telling the builder what to do. I'm more just curious and want to be educated on what might get me to the ride that I'm looking for in the frame.

mhespenheide

10-03-2017, 11:06 AM

I don't understand the strong responses from some posters about asking a framebuilder to build with certain materials. To extend an analogy, if I'm working with a professional tailor, I'm certainly going to ask him or her to work with either heavy wool, light wool, cotton, etc. I may even ask for either an "Italian" fit or an "English" fit.

I'm certainly not going to call up Richard Sachs and specify a tubeset. But if I'm the OP, I might well call up Jeff Lyon and say that I'm interested in this type of bike; I've heard about this kind of ride, and what would he think about working with thin wall tubing.

disspence

10-03-2017, 11:11 AM

If energy stored in the frame can drive more power to the rear wheel, then energy stored in the cranks should do it even more efficiently! I just installed this cranks on my bike, and I can't wait to reap the benefits of 15+% more power!

http://pardo.net/bike/pic/mobi/d.interdrive-crank/farm7.staticflickr.com/6156/6231286452_105fa3d08a_o_d.jpg

Hilarious!:hello: :beer:

El Chaba

10-03-2017, 11:13 AM

There's a tradition-especially in the US- of the customer turning the specifications on a custom bike into an exercise in OCD....specifying every part down to the last nut. Telling the builder what gauge of tubing, what lugs, etc. I would imagine is just the next level....

bicipunk

10-03-2017, 11:18 AM

I'm certainly not going to call up Richard Sachs and specify a tubeset. But if I'm the OP, I might well call up Jeff Lyon and say that I'm interested in this type of bike; I've heard about this kind of ride, and what would he think about working with thin wall tubing.

This ^^ is what I'm getting at. Just trying to hear some opinions....

false_Aest

10-03-2017, 08:56 PM

I don't understand the strong responses from some posters about asking a framebuilder to build with certain materials.

Go solicit a client that thinks they know more than you do about your job then try to work for them (not with).

mhespenheide

10-03-2017, 09:09 PM

Go solicit a client that thinks they know more than you do about your job then try to work for them (not with).

I do it more often that I care to, thank you.

Doug Fattic

10-04-2017, 09:35 AM

I was always under the impression that tubing diameter (and shape) contributed more to stiffness than wall thickness. But in your 3rd paragraph seems to slightly contradict that -- maybe I'm misreading?

Yes, tubing diameter makes a big contribution to frame stiffness. One of my framebuilding class students that is an engineer calculated that a 1 1/8th" top tube with a wall thickness of .7/.4/.7mm had approximately the same stiffness as a 1" top tube with .9/.6/.9mm walls. What I was trying to say is that I can tell the difference in ride feel between a frame that has a 1" top tube with 7/4/7 walls compared to either one that also has a 1" top tube with 9/6/9 walls or one with 1 1/8th" top tube with 7/4/7 wall thickness.

To your idea of a "lively" bike, that seems to be a bit different than what Jan is talking about. Your description makes me think of a bell or tuning fork. If a bell is made well it will sound beautiful, if it's not done right it's horrible and shrill. Seems to be a similar when building a bike ... it's gotta be tuned and a 1-size fits all doesn't work for some folks.

My personal observation of riding a bicycle with a frame built with 7/4/7 standard tubing is that it has a feel that is different than riding frames with heavier walls or bigger diameters. To me it is noticeable and I very much prefer it. It isn't about the weight savings but the ride quality. I am 5'8" and light and can pedal smoothly so obviously what works best for me may not apply to bigger more powerful riders with a different kind of pedal stroke.

The other point I wanted to emphasize is that there probably aren't many cyclists that have actually ridden a 7/4/7 frame with a 1" top tube. Not many have been made. I have not only ridden the several I've built for myself but others I have made for customers. However that hasn't stopped a whole lot of people having strong opinions just from reading.

Ken Robb

10-04-2017, 10:27 AM

I guess my stock 60cm Legend ti "planed". It had a slightly springy feel but never felt wobbly or too "flexy". Maybe some riders would have been happier with a stock Serotta than the one where they had a lot of input regarding custom features and design?

To some extent I think people often tend to choose sports equipment that is stiffer than they need. I have seen it in tennis rackets, golf clubs and skiis. They think if a pro plays a stiff shaft they should too but their swing speed isn't fast enough to benefit from it and they would gain distance if they used softer shafts that could add a little "snap" to their swing.

Mark McM

10-04-2017, 10:38 AM

Go solicit a client that thinks they know more than you do about your job then try to work for them (not with).

Maybe its just me, but I'd expect that creating bespoke products would be a collaboration between client and provider. The client knows more than the provider about what qualities the product is expected to have, and the provider knows more than the client about how to achieve those qualities. Just as bad as a client telling a provider how to do their work, is the provider telling the client what they want. As such, it would behoove the client to know at least a little about the work, to make sure the provider is achieving what they want, just as much as it would behoove the provider to understand how the client will be interacting with the product. In both cases, there is nothing wrong with the one side lending some guidance to the other, if they think the creation of the product isn't heading the right direction.

moobikes

10-05-2017, 06:33 PM

Here is a response from Mike Kone on the Classic Rendezvous list about lightweight bicycle tubing. He is the guy behind Boulder Bicycles and for a time the revived Rene Herse brand.

>>>>>>>>>>>>>>>>>
From Mike Kone:

We play around constantly with light gauge tubes on bikes we design here.
A few observations in no particular order. And remember, these are just
our thoughts and experiences, and others (especially builders) may have
different thoughts or observations that may be equally or more valid.

1) Some folks just can't notice what the frame tubing is. Others can .
The crazy thing is that how a bike "feels" may be dependent on the bike (s)
you've been riding before. Its all about the rider getting in sync with
the flex of the frame. But many riders really prefer the lighter tubes.

2) If a frame is either way to stiff or way to flexy for some riders, they
just know it doesn't seem to work, but they can't tell why! And sometimes
a really stiff frame may feel great to rider, and a really flexy one works
great too and one in the middle just is wrong. I have no idea why.

3) I think there is a strong "mental" element to frame flex. Like hearing
some of the crazy things that audiophiles claim to hear (no, lets not go
into that, wrong forum). I swear there is a placebo effect with frame
tubing. I've tricked myself.

4) Oversize light tubes I believe transmit road shock differently. For
really skinny tires long we used to ride, the oversize tubes felt great and
more planted and that is why they took off in the early 1990's. When you
go to a 28 or 30mm tire, the skinny tube bikes start working really well.
Less than 25mm and its kinda harsh with a typical Columbus SL/531 frame.

5) With light tubes, shimmy is an issue. Especially on rando frames.
Contributing factors to shimmy are weight far back, a low trail geometry,
handlebars that are relatively high that get the weight back. And finally,
some riders have a natural "shake" frequency that invites a shimmy. That
is why some riders on a give bike may have issues, and then lots of other
riders will never have a problem. Headset choice and even grease can
impact the natural ocillation of the bike so can change shimmy likelihood.

6) Non-racers tend to benefit more from light tubes as they tend to flex
the frame less naturally.

7) For many light riders, especially women, the bike's they've tried have
probably all been too stiff.

8) There is never a reason to go lighter than skinny 8/5/8 on a downtube.
I suppose for a 90lb women it could make sense as the exception. But its
harder to discern a down tube being stiffer than it is a top tube - the top
tube flexes like crazy in torsion and of the main tubes has the most
profound effect on the feel of the frame.

9) Light tubes can feel less "planted" - on initiation of a turn, the very
light tube bikes wiggle a bit. For many folks, its not an issue. But a
frame a tad stouter than the "lightest" may give a bit more of a planted
feeling. Especially true with light oversize frames.

10) Optimal tube choice is very rider and frame size specific. We NEVER
use a 7/4/7 skinny top tube on a top tube that is over 57.5cm cc.

I know that a bit of this may turn folks off from the light tubes, but that
is not my intent. Many folks love the really light tubing including myself
on some bikes I have. But I also love my old Cinelli (I think it has a
Reynolds 8/5/8 top tube).

One more thing - we don't use the Kesai forkblades much. For one thing,
they have not passed the EN standard and therefore Waterford won't use them
on our Boulder Bicycles. I really don't think its an issue in practice,
though, as blade failure is so darn unlikely. But in my mind, maybe its
the placebo effect, I've always felt that bikes with the Continental oval
instead of the Imperial oval like the Kesai blades feel more "planted" when
I stand and sprint (or climb a hill). Interestingly, Rene Herse on some of
his race bikes and on some go-fast rando bikes actually used round blades.
And on his race/road sport bikes, when he used Imperial oval blades he
tended to use really stout blades. He might have been concerned about this
issue as well. But for a rando bike where one is sitting and spinning most
of the time, I can see the appeal of the comfy Kesai blades. We've used
them on some Rene Herse bikes.

Mike Kone in Boulder CO USA

false_Aest

10-05-2017, 07:31 PM

Maybe its just me, but I'd expect that creating bespoke products would be a collaboration between client and provider. The client knows more than the provider about what qualities the product is expected to have, and the provider knows more than the client about how to achieve those qualities. Just as bad as a client telling a provider how to do their work, is the provider telling the client what they want. As such, it would behoove the client to know at least a little about the work, to make sure the provider is achieving what they want, just as much as it would behoove the provider to understand how the client will be interacting with the product. In both cases, there is nothing wrong with the one side lending some guidance to the other, if they think the creation of the product isn't heading the right direction.

Mark, I think you're right. There is a collaborative aspect to working with any (good) client.

FlashUNC

10-05-2017, 07:37 PM

It's a give and take. I remember getting a stem for my Della Santa from Eric at Winter, I admittedly gave him some bad ideas I was tossing around and he steered me 100% in the right direction.

A good builder will save you from your own bad choices is you listen.

But other than general characteristics, man, I wouldn't go in and specify tubesets.

adampaiva

10-05-2017, 10:33 PM

It doesn't need to be so black and white. To dictate to the builder that I know what my tubing should be would be a bit much and obnoxious. But now that I have and really like this skinny light tubing thing, I would want my next custom bike to also have these same characteristics and if the builder was offended by my saying that I really enjoy my L'Avecaise and I am pretty confident that a main factor of what I like so much about this bike is this tubing spec, well then I've gone to the wrong builder. But I think if I do get another custom bike (and I would want to replicate the ride characteristics of my L'A if I do), I would specifically be shopping at builders that build in this niche of the bike world. I think it's perfectly acceptable and not rude to expect to be able to give some design input like that, but yes if I went to the wrong place like if I went to Spooky and asked for a planing bike with a 1" 747 top tube then I shouldn't be offended when he says no get lost.

bicipunk

10-06-2017, 05:24 PM

jimoots

10-08-2017, 12:55 AM

The concept of planing is absurd; and anyone with any exprience pacing intervals to a power meter can poke holes through their testing methodology.

Sitting the same guy on a bike for five “all you got” efforts and holding that up as your proof... it’s lazy and misleading to the casual reader who might actually place weight behind what’s being read.

And I found myself wondering if the author actually understood the concept of power as I read through the article.

Simply put if there was a 15% increase in power waiting to be unlocked based upon bikes - it wouldn’t be a concept being floated on the backwaters of the internet and there would be serious pro team R&D going into it.

But there’s not, so there isn’t.

rain dogs

10-08-2017, 04:20 AM

Some of the stuff I read in BQ... man. I appreciate his passion, but it's a total echo chamber.

Maybe it's too obvious to state but power doesn't come from a bicycle unless it's electric. Nor from flex, nor from bigger tires, nor from 'planing'

Power comes from the rider. If you put 200W into a bike, you put in 200W. From there it's loss. There is no "more power" or "free power" or "increases" that's all mumbo jumbo.

In theory, it could be "more/less loss" when it comes to actually moving you forward, but you put 200W in, you want as close to the 200W out. Simple. Jan will lead you to believe that you put 200W in, and X is lost into frame flex/heat (because thermodynamics exist) and then X+Y is coming back?!?!? It cannot be X+ anything because the universe would implode.

It's X-Y coming back. And I am willing to bet you the "Y coming back" is so immeasureably small that it is inconsequential, the same with all of his vibrating molcules theory in the rider. Make the choice for comfort, not "free power". Some miniscule truth may be there, but it's better to call that preference, because we're also dealing with such TINY numbers. 200W is a tiny amount of power. His 15% claims, which are laughable, would be 30W which is miniscule power, and if it is actually 1 or 2 W here or there.... that's inconsequential, especially for the "real world" riders of the world. But hey, like changing 4g bolts for 2g bolts, if this is your thing - free world.

Forest thru the trees and all that.

marciero

10-08-2017, 06:52 AM

Some of the stuff I read in BQ... man. I appreciate his passion, but it's a total echo chamber.

Maybe it's too obvious to state but power doesn't come from a bicycle unless it's electric. Nor from flex, nor from bigger tires, nor from 'planing'

This is a total misreading. Nowhere is this claim made.

Simply put if there was a 15% increase in power waiting to be unlocked based upon bikes - it wouldn’t be a concept being floated on the backwaters of the internet and there would be serious pro team R&D going into it.

But there’s not, so there isn’t.

I'm so tired of this argument. The fact is that no one does this kind of R&D, with real riders. Why should they when everyone simply accepts the stiffer-is-better mantra? When companies need only mass produce bikes in three sizes in Asia and furnish them to pro teams to get them sold there is no incentive. Having based all their marketing for years and years on stiffer is better there would be a natural reluctance to even allow the possibility that "...um, it's not that simple..." That the women's time trial world champion could not even get a frame in her size from the sponsor speaks volumes about how interested companies are in optimizing frames for individual riders.

How long was it simply accepted that higher pressure tires were faster? After literally decades, you finally have tire companies doing their own testing and finding that, as BQ has been saying for 10 years, no, it is not that simple, and professionals are finally using 28+ tires in races like Paris Roubaix.

Many here are honed in on this 15% number, take it out of context, and apply to all riders in all situations. It is one test, and I doubt that number would hold up to further testing. But rather than just dismissing, calling BS, and crying absurd, it would be nice to actually cite some study or test, or even some anecdotal evidence. Even anecdotal would at least be something. When someone here relates their actual non-scientific experience I usually give that at least some weight based on who it's coming from. But people just simply seem unwilling to even allow the possibility that for SOME riders in SOME riding conditions, a flexy frame MAY have a benefit over a stiff one. My own anecdotal would go something like this "on rides of 100 miles or more I am not slower, and possibly faster, and am also less fatigued, on my cheap Asian made skinny tube frame than I am on my "nicer" other bikes."

There is a recent podcast, yes with Jan Heine, but also engineers from, I think Cannondale or Specialized, finally allowing that stiffer may not always be better.

rain dogs

10-08-2017, 02:08 PM

This is a total misreading. Nowhere is this claim made.

It's made in numerous articles he writes about planing and the like: "We know that riders put out up to 15% more power on bikes with optimized flex characteristics."

BS. Riders don't 'put out' 15% more power because they are on a flexy bike. Or maybe they do because they ride harder during that part of the test, and ride casually during the other parts. A rider will put out X power, and the bike is moving at speed because of X Power minus losses. And for a test to be meaningful a rider should put out the exact SAME power, not '15% more' or 15% less.

If Jan wants to say: The power recorded at the wheel was 15% greater on the flexy bike than the power recorded at the wheel on the stiff bike.... fine (but unlikely). But even if that's what his small qty of data shows it is totally meaningless unless we know the power the rider was actually producing was exactly the same (and recorded numerous times for a realiable sample size under controlled conditions)

I can "put out 15% more power on a Wal-mart Huffy" than I can on a specialized Venge if I want to and decide to pedal wth variable power. I can quite easily ride a Venge at 150W and a Huffy at 173W. But that doesn't mean I should ride a Huffy if I want to go faster, further or have higher performance.

He repeatedly makes these types of conclusions. If you want to put out more power, ride a flexy bike! As if the flexy bike somehow enables you to overcome your physical limits and magically 'put out' more power! Sounds easy... why train? :banana:

And for what it's worth, and I said it above, choose the flexier bike if you wish. Choose if for comfort, choose it for a nice ride. Choose it because, maybe you will in fact see the tiniest less loss of power into the frame (1 or 2W) due to a myriad of dynamics. But don't choose it because you believe you're suddenly going to increase your FTP by 15%, or start 'putting out' 15% more power.

etu

10-08-2017, 04:04 PM

There is a recent podcast, yes with Jan Heine, but also engineers from, I think Cannondale or Specialized, finally allowing that stiffer may not always be better.

It's interesting how heated the debate gets when it involves Jan, almost like Grant Petersen, eh? I think no matter where you stand on the planing argument, it's hard not to admit he is probably top one or two most influential individuals for us recreational cyclists. Who has been leading advocate for larger tires and more flexible frames that are now so accepted as norm.
I am actually very grateful for his contribution to the sport in general and I feel that he has helped me with real, genuine improvement in my riding experience. From this perspective, I am much more inclined to give Jan the benefit of the doubt if there is a point that he makes that doesn't make sense to me.
Having read most of what he wrote frame flex and having subsequently ridden a fair number of miles on flexible frames, I didn't interpret his message to mean that a flexible bike will give you more power. No, I think he challenges you to consider that a bike with flex characteristics that match your pedaling style better might motivate you to push, harder and therefore go faster. The idea of bike and rider being a synergist whole is pretty cool IMO. This idea does not seem alien to custom builders, e.g. Dave Kirk and Carl Strong. Jan just has done a great job publicizing it and showing us the possibilities.

marciero

10-08-2017, 06:58 PM

It's made in numerous articles he writes about planing and the like: "We know that riders put out up to 15% more power on bikes with optimized flex characteristics."

No BQ claims ever violated the second law of thermodynamics, which is what you suggested. "Jan will lead you to believe that you put 200W in, and X is lost into frame flex/heat (because thermodynamics exist) and then X+Y is coming back? where Y>0.

BS. Riders don't 'put out' 15% more power because they are on a flexy bike. Or maybe they do because they ride harder during that part of the test, and ride casually during the other parts. A rider will put out X power, and the bike is moving at speed because of X Power minus losses. And for a test to be meaningful a rider should put out the exact SAME power, not '15% more' or 15% less.

If Jan wants to say: The power recorded at the wheel was 15% greater on the flexy bike than the power recorded at the wheel on the stiff bike.... fine (but unlikely).

A rider will produce more power if they are less fatigued, or more efficient. But you've raised, and perhaps conflated, two separate questions-whether there is energy that is stored in the frame and returned to the rear wheel with a flexy frame, and whether the rider is able to produce more power with the same effort and level of fatigue. To test the latter, and in particular whether it depends on frame/rider dynamics, you would need a test of average power over some duration- it makes no sense to have the the rider produce the SAME power, unless you wanted to ask them afterward if they were more or less fatigued, which would be okay, though more subjective.

Many of us have worked to reduce inefficiencies in our pedaling motion. Is it so much of a stretch to entertain the notion that the frame itself might be part of that equation?

El Chaba

10-08-2017, 07:00 PM

What makes a bike great is *balance*, and it is exactly what is lost on many (most) modern big box bikes. They can measure stiffness and add more, measure weight and reduce it....make it steer more quickly, etc...The talent and art comes in finding the balance point for any given parameter....

adampaiva

10-08-2017, 08:22 PM

I don't know about other BQ readers and fellow owners of flexy skinny tubes planing bikes, but I am smart enough to take any and every thing Jan says with a grain of salt. And tbh I really don't care if I have 15% more power or if I am losing 15% because I just really do enjoy the ride of this bike more than my other bikes. And the sort of rides he does stories on are the same sort that I like to do. And I haven't found another cycling magazine to read that I like and its nice to still nerd on bikes but get off the internet.
I think we've digressed. What was the original question.

weisan

10-08-2017, 08:43 PM

https://i.pinimg.com/736x/aa/07/8a/aa078a916fa68cdd6ffaa15a3cf3dc4a--antique-bicycles-electric-bicycle.jpg.

https://static1.squarespace.com/static/560f1941e4b0e75bc493a695/t/560f1d05e4b0eb177e2d69d6/1443833074834/old-hickory-wood-bicycle.jpg

FlashUNC

10-08-2017, 09:27 PM

Aging MAMILs have more to do with the self-justification of searching out wider tires and less stiff frames -- and an industry looking for a marketing veneer to cover for the realities of why that is -- than any arbitrary sense that more cushion and more flex are mo' betta.

adampaiva

10-08-2017, 10:33 PM

geordanh

10-08-2017, 10:56 PM

His tests are absurd to me, and to draw conclusions from them is nuts. I'm not a smart guy about science and stuff but the problems with his 'tests' in his magazines seem so blatant to me.

There's no control variable! If you really wanted to test his theory, you'd keep either power or speed constant on bikes with identical vertical compliance because at the end of the day, what he's saying is that lateral loading of a flexible frame as a spring makes you pedal more efficiently. Modern carbon all rounder road bikes have largely solved the vertical compliance comfort issue relative to steel so we should eliminate that as a test factor.

If you keep speed up a particular climb constant, according to Jan, the springy bike should be able to maintain a certain speed at a lower power output at the crank, right?

If you keep power at the crank constant, the springy bike should be faster up the climb, right?

What am I missing here? Why would he keep both speed and power as variable in a test like this? Just seems insane to me and so obviously open to tester manipulation.

If his point is that power output at the end of a long day is greater because the flexy frame is more comfortable, leaving a rider more fresh, that seems to hard to test under repeatable conditions. I do believe it, however, modern, non-aero-first carbon road bikes are, in my experience, no less comfortable than old, flexy steel frames. This wasn't the case 10 years ago, but these designs have come a long way in vertical compliance. Yet, they are vastly superior laterally and respond incredibly out of the saddle under high power.

etu

10-08-2017, 10:57 PM

hey I had to google that but at 33 I hope I'm not MA and should take offense :eek: I did just come back from French Fender Day and was about half the average age of attendance.

To the OP. Don't do it. You'll be slow and won't like your bike and your friends will make fun.

I am MA and I'll vouch that dropping testosterone levels and receding hairlines lead to a 15% increase in intensity of devotion to wider tires and flexible frames! :butt:

R3awak3n

10-08-2017, 11:04 PM

I don't have a lightweight tubed bike so can't comment on planning but I like Jan enough. I am with Adam, there is no other cycling magazine I like to read, BQ is great and always interesting even though I don't always buy the stuff Jan sells. Its cool though. The guy has introduced some of the best tires in the market right now and really pushed for 650b stuff which is all stuff I like. He has super cool bikes and features awesome bikes in the magazine.

Planing, maybe exists, maybe not but sometimes I feel good on the bike and everything seems in tune and turns out to be a great ride, sometimes it doesn't. Stiff is not always better but springy is not always better either. Every bike for a different occasion is how I see it.

marciero

10-09-2017, 05:09 AM

What am I missing here?

You are conflating the two issues I mentioned.

...and speaking of carbon-it is too bad no one seems interested in testing different layups. If planing is a real phenomenon and people are not just imagining it or making it up, and if it is attributable to frame flex in certain places I would think it could be dialed in and isolated better with carbon.

geordanh

10-09-2017, 09:06 AM

You are conflating the two issues I mentioned.

...and speaking of carbon-it is too bad no one seems interested in testing different layups. If planing is a real phenomenon and people are not just imagining it or making it up, and if it is attributable to frame flex in certain places I would think it could be dialed in and isolated better with carbon.

Ok. So the test should then be power kept constant over some repeatable period of time, and heart rate should be lower for a given effort on the flexy frames. Right?

Sent from my iPhone using Tapatalk

Doug Fattic

10-09-2017, 12:20 PM

I always feel that whenever a discussion starts about Bicycle Quarterly and “planing” they unfortunately almost always go off the rails. I am a frame builder that has actually built frames out of .7/.4/.7 (for myself and others) and like the ride of them better than frames built out of heavier or bigger diameter tubing. As I mentioned before it is easy for negative opinions on the theory of “planing” to erode into negative attitudes onto frames built with thin wall standard size tubes (with 1” top tubes). The 2 should be kept separate.

When I ride a frame built out of heavier wall standard or oversize tubing they feel clunky by comparison. I suppose it is like going from a double butted frame to one built with straight gauge “hi ten” (which stands for hi tensile steel). They have a dead feel. Production steel frames were built so that the biggest heaviest strongest person would not break them and as a result sue the company. They also made/make frames out of heavier tubing because it is easier manufacturer. So tubing choice was not chosen by companies that made bicycles in volume for what would be the ideal ride quality of an average person.

Jan Heine studies of classic European builders has been an enormous benefit to American frame builders. He has had more influence than any other single source. As riders have aged and no longer want a racing bicycle and younger riders are wanting practical bikes to ride for transportation, we don’t have to reinvent the wheel again but look at Jan’s research to see what worked well in the past. His curiosity on why he liked his Rene Herse bicycle (made in Paris by one of the best custom builders in the world) better than his Bob Jackson (a custom builder in England) led to his discovery of the advantages of thin wall tubing over heavier stuff. I learned how to build frames in England in the middle of the 70’s and the type of custom bicycles there and in France were different.

My personal bicycle built with standard size tubing with .7/.4/.7 wall tubing is not “flexy”. I don’t feel it bending at all when I pedal. Actually my frame built with .6/.3/.6 didn’t feel flexible to me either. They just don’t have that clunky heavy feel. Only when I got out of the saddle in a sprint could I notice any flex on the 6/3 (and I rarely ever do that). I don’t ever feel flex in my 7/4 frame. I would be interested in the observations of others that have actually ridden this kind of frame. I am not interested in critical opinions of those that haven’t.

Because I greatly prefer my 7/4 frame to heaver ones and have genuinely appreciated Jan’s body of work, I hold my thoughts on “planing”. I don’t think as of yet there is complete understanding of the different ride characteristics of frames made from a variety of tubing diameters and wall thickness and heat treatments. I don’t know why my light skinny tubes frames have a superior ride. I have heard various theories from other builders but I’m not sure anyone really knows yet.

bicipunk

10-09-2017, 02:32 PM

To the OP. Don't do it. You'll be slow and won't like your bike and your friends will make fun.

Haha I'm 23... All my riding friends (who are always older than I) don't make fun of me because I hold my own in the paceline on brevets and they get a wonderful draft because of it :)

marciero

10-09-2017, 03:08 PM

Ok. So the test should then be power kept constant over some repeatable period of time, and heart rate should be lower for a given effort on the flexy frames. Right?

Sent from my iPhone using Tapatalk

Something like that, yes.

rain dogs

10-09-2017, 03:08 PM

No BQ claims ever violated the second law of thermodynamics, which is what you suggested. "Jan will lead you to believe that you put 200W in, and X is lost into frame flex/heat (because thermodynamics exist) and then X+Y is coming back? where Y>0.

A rider will produce more power if they are less fatigued, or more efficient. But you've raised, and perhaps conflated, two separate questions-whether there is energy that is stored in the frame and returned to the rear wheel with a flexy frame, and whether the rider is able to produce more power with the same effort and level of fatigue. To test the latter, and in particular whether it depends on frame/rider dynamics, you would need a test of average power over some duration- it makes no sense to have the the rider produce the SAME power, unless you wanted to ask them afterward if they were more or less fatigued, which would be okay, though more subjective.

The second law of thermodynamics is the entropy law. And I never suggested that his claims violate thermodynamics, just common sense.

You do know the test he lists was a sprint, correct? 300m if I recall. This isn't a test over a brevet.

All I'm wondering is where this extra 15% output is coming from? Is it coming from the rider? (If so, that capability should exist with all bikes. If you're doing a 300m sprint you can't just suddenly "find" 150 never found before Watts. If it's the bike, how does the bike produce power? Magic? Electric?

The energy put into a spring doesn't come back with MORE energy. A spring doesn't create energy. Can we at least agree on that?

marciero

10-09-2017, 08:06 PM

The second law of thermodynamics is the entropy law. And I never suggested that his claims violate thermodynamics, just common sense.

You do know the test he lists was a sprint, correct? 300m if I recall. This isn't a test over a brevet.

All I'm wondering is where this extra 15% output is coming from? Is it coming from the rider? (If so, that capability should exist with all bikes. If you're doing a 300m sprint you can't just suddenly "find" 150 never found before Watts. If it's the bike, how does the bike produce power? Magic? Electric?

The energy put into a spring doesn't come back with MORE energy. A spring doesn't create energy. Can we at least agree on that?

No, springs wont create energy. His claim is that the capability does not exist, or is not the same with all bikes. In the first article that was cited are the test results-yes, for short sprints. In the second article he conjectures as to why the output is not the same, essentially that on a non-flexible frame less of the rider effort is converted to work, and why this might be so. (I think the all-out effort is an attempt to ensure that the effort is close to the same, or follows a predictable downward trend.) I just think the test itself, even setting aside questions like statistical significance (small sample size...), along with all the anecdotal experience, at least raises questions for further investigation or testing. He mentions some other tests but I've not seen or cant recall them.

Mark McM

10-10-2017, 09:45 AM

No, springs wont create energy. His claim is that the capability does not exist, or is not the same with all bikes. In the first article that was cited are the test results-yes, for short sprints. In the second article he conjectures as to why the output is not the same, essentially that on a non-flexible frame less of the rider effort is converted to work, and why this might be so. (I think the all-out effort is an attempt to ensure that the effort is close to the same, or follows a predictable downward trend.) I just think the test itself, even setting aside questions like statistical significance (small sample size...), along with all the anecdotal experience, at least raises questions for further investigation or testing. He mentions some other tests but I've not seen or cant recall them.

I think there are only 3 possible explanations for the "more power" claim:

1) A "planing" bike returns more of the energy that is transferred into it.

2) A "planing" bike makes the rider produce power more efficiently.

3) A "planing" bike allows the rider to generate more power.

I think we can put number 1 to bed, based on evidence we already have. A rider applies power to the bike through the cranks/pedals, and the power is applied to the road through the rear wheel. Any energy that is absorbed or returned through flexing of the bike must therefore occur somewhere between the cranks and the rear wheel. There are plenty of reports of bikes with both a crank or pedal power meter and a wheel power meter that shows that the wheel power meter will report a few percent less power than the crank power meter. However, other tests have shown that typical chain drive is about 95-98% efficient, so the power difference between crank/pedal power meters and wheel power meters can be completely accounted for through drivetrain friction. There is no evidence of any significant power/energy lost in the frame.

I don't know of any specific evidence about number 2, although I think it can be obtained. Bicycle metabolic power testing is now available to the general public (through companies like https://www.intelligentfitnessvermont.com/ or http://www.hopecam.org/race-for-hope-blog/2017/4/3/metabolic-testing). Testing riders on "planing" and non-"planing" bikes should be able to determine if the riders have any metabolic differences between the frames.

There might be a little bit of truth behind number 3 - but in the opposite way as claimed for "planing" frames. If a bike is so flexy that it becomes difficult to control when applying large drive forces, than that could certainly produce a limit to how much power a rider can produce and still be able to control the bike. But I think a bike would have to be very flexy before this becomes significant. And this would only come into play during maximum power sprint efforts - lower power endurance efforts would probably not be affected.

(Anecdotally, I do own a very flexy bicycle frame - 2002 Litespeed Ghisallo, then the lightest production bike frame in the world, and often regarded as one of the flexiest bikes in the world as well. My Medium/Large model frame weighs 865 grams, which is very light for a titanium frame, and comparable to the lighter carbon fiber frames today. The frame visibly flexes under hard out of saddle efforts, and you can even feel the frame flex under rapid steering maneuvers. I'm pretty sure I can't sprint as fast on this frame as I can on my stiffer bikes, due to my inability to apply maximum muscle force because of frame flex. On the other hand, I can do longer sustained steep climbs faster on this bike. In addition to the light frame, this bike also has ultra-light wheels and components, resulting in a total bike weight of about 4 -5 lb. less than my other bikes, or a total bike/rider mass decrease of about 3% - which corresponds to about how much faster I can do sustained steep climbs on this bike.)

Wayne77

10-10-2017, 11:27 AM

This is about efficiency. The language and terminology in the BQ testing is misleading...Barring the addition of other energy inputs/torque generating devices like electric motors, "more" power simply cannot be generated by any static component or frame construction in the complex chain of events between power to the pedal and power between tires and road. EVERYTHING after the power to the pedal is a loss. A 100% efficient'system (the frame being only one variable) would transfer 100% of the energy to the road. It is IMPOSSIBLE for a spring to generate more energy. A spring simply takes some energy input, stores it, and delays the output. But there is still some incremental loss (i.e. cost) in doing so. The question is whether the delay, from a timing perspective, is helping or hurting the efficiency of the overall system. To suggest that it can help universally, without accounting for so many other variables that hurt or improve efficiency is not even close to being scientifically valid. Some frame flex may help one person and hurt another...or work well for one type of bike or mode of use but not another (climbing, sprinting, continuous power, burst power) or may hurt or help one persons perception a given frame "feels good" purely from an intangible enjoyment perspective. I imagine a frame that "feels good" could contribute to someone being faster...regardless of whatever factors we think contribute to those good vibes actually improve efficiency of power delivery.

It's quite possible that there is no direct correlation between "I love the way this frame feels!" and "this frame is a faster climber/sprinter/descended/etc"

I get the hobby driven enthusiasm and "joy of scientific discovery" the article is coming from, but suggesting the findings are scientifically valid, and especially concluding that the results based on an EXTREMELY small sample size are reliables is a stretch. Let's just call it what it is and appreciate it that way...nothing wrong with enthusiastasts expressing that certain frame qualities seem to help them feel faster or SEEMINGLY made them faster in a few cases.