Does anyone compare threadless stems on a quill equivalent length basis?

[RPS]

For years we got by with essentially one dimension for sizing stems. When bikes had traditional “7” quill stems, we bought a 10, 11, 12 CM etc… and adjusted it up or down as necessary. It seemed very straightforward – one number told us everything we needed to know.

I’m curious if anyone compares threadless stems on a “quill equivalent” basis as in the old days (rather than or in addition to the common “length and angle” or “rise and reach” formats)?

Would it not help those who don’t like crunching numbers, or would it oversimplify to the point of being misleading?

[atmo]

sure, i do.

nothing has changed except where the top of the headset
is. the path that the hands take to get where they need
to be is the same, except we now have the additional
aesthetic of sloped top tubes, longer (than often needed)
head tubes, and stems that are right angle-ers. oh, and the
spacers too. mebbe adam in michigan will get that quote
out - the one about quills and all that.

i'm a level top tube guy. 84 degree stems and mebbe 2
king cycle spacers (one 6mm and one 12mm used together)
gets me wet and sticky atmo.

hey, gotta go.
i'm driving miss debbie to school now atmo.

[RPS]

ATMO, I’m thinking more in terms of whether there would be value in a rating system to convert the typical “length and angle” of any given threadless stem to a single quill-equivalent length so when I look at two similar threadless stems, I can tell right away what the final impact will be once I install it; and without having to use a calculator. As far as I can tell, that information is not readily available.

In the past we knew without doing any calculations that an 11 CM was 1 CM longer than a 10 CM no matter where the bar height was to be set. Today it seems more complicated because we have two variables (reach and rise) which are evaluated differently than before as they relate to the bicycle -- IMHO. A 10 CM stem with +/- 6 degrees can be installed two different ways with different reach and rise numbers, but it’s still one stem. Does that make sense?

Assuming I know my bars will end up at the same elevation, I want to know immediately what the difference is between an 11 CM X -17 degrees and a 12 CM X 0 degrees. It’s not that most of us can’t run the numbers (which can get complicated), but why should we have to? Was the old "7" system better/easier to use and more informative? Maybe not.

[atmo]

ATMO, I’m thinking more in terms of whether there would be value in a rating system to convert the typical “length and angle” of any given threadless stem to a single quill-equivalent length so when I look at two similar threadless stems, I can tell right away what the final impact will be once I install it; and without having to use a calculator. As far as I can tell, that information is not readily available.

In the past we knew without doing any calculations that an 11 CM was 1 CM longer than a 10 CM no matter where the bar height was to be set. Today it seems more complicated because we have two variables (reach and rise) which are evaluated differently than before as they relate to the bicycle -- IMHO. A 10 CM stem with +/- 6 degrees can be installed two different ways with different reach and rise numbers, but it’s still one stem. Does that make sense?

Assuming I know my bars will end up at the same elevation, I want to know immediately what the difference is between an 11 CM X -17 degrees and a 12 CM X 0 degrees. It’s not that most of us can’t run the numbers (which can get complicated), but why should we have to? Was the old "7" system better/easier to use and more informative? Maybe not.
to quote pluto -
my advice to you is to start drinking heavily atmo.

[93legendti]

sure, i do.

nothing has changed except where the top of the headset
is. the path that the hands take to get where they need
to be is the same, except we now have the additional
aesthetic of sloped top tubes, longer (than often needed)
head tubes, and stems that are right angle-ers. oh, and the
spacers too. mebbe adam in michigan will get that quote
out - the one about quills and all that.

i'm a level top tube guy. 84 degree stems and mebbe 2
king cycle spacers (one 6mm and one 12mm used together)
gets me wet and sticky atmo.

hey, gotta go.
i'm driving miss debbie to school now atmo.

Sheesh, you're going to make me work...

[atmo]

Sheesh, you're going to make me work...
get that other one that you had as a sign for a while atmo.

[93legendti]

get that other one that you had as a sign for a while atmo.


This one?

Originally Posted by e-RICHIE:
"... where were you all in the pre-90s
when folks had some quill showing yo? nobody was ranting
about head tubes needin' watering so as to grow up higher.
or-were-they?!"
http://forums.thepaceline.net/showpost.php?p=185644&postcount=14

http://forums.thepaceline.net/showthread.php?t=15859&highlight=folks+quill+showing

[atmo]

This one?

Originally Posted by e-RICHIE:
"... where were you all in the pre-90s
when folks had some quill showing yo? nobody was ranting
about head tubes needin' watering so as to grow up higher.
or-were-they?!"
http://forums.thepaceline.net/showpost.php?p=185644&postcount=14

http://forums.thepaceline.net/showthread.php?t=15859&highlight=folks+quill+showing
yes.
brilliant atmo.

[93legendti]

yes.
brilliant atmo.

Agreed.

[RPS]

OK, I know sizing methods are not as interesting as discussing aesthetics for many, and I hate to be specific for fear of painting a target, but here it goes:

12 CM (-17 degrees) = 12 CM quill equivalent

12 CM (- 6 degrees) = 12.48 CM equivalent

12 CM (zero degrees) = 12.55 CM equivalent

12 CM (+ 6 degrees) = 12.48 CM equivalent

12 CM (+17 degrees) = 12 CM equivalent

12 CM (+30 degrees) = 10.87 CM equivalent

12 CM (+40 degrees) = 9.61 CM equivalent

Unless I screwed up the math, these different 12 CM threadless stems would have the equivalent lengths shown above. Therefore, we can very quickly compare the final impact different stems will have provided the bars are set a certain known distance below the saddle. We can very quickly see that regardless of how we install it (more or less spacers and upside down or not), the zero or +/-6 will be approximately half centimeter longer than a +/-17 degree stem of the same length (extension).

I’m not questioning aesthetics at all, just the method for comparing one stem versus another. Is this too simplistic to get the job done? Am I missing something obvious?

[Grant McLean]

We can very quickly see that regardless of how we install it (more or less spacers and upside down or not), the zero or +/-6 will be approximately half centimeter longer than a +/-17 degree stem of the same length (extension).


The funny thing about the beloved "Pearl" Nitto quill is that they measure
the same as an 80' ahead, becuase they are a little 'long' for the stated size.

The 'pearl' 10 is about 10.7 compared to any other quill, and the exact same
reach as an ahead 10cm 80' stem. It's like they knew we'd all come back...

g

[fiamme red]

yes.
brilliant atmo.+3.141592653589793238462643383279502884197169 399

[catulle]

Thread of the day. Better than AI.

[mosca]

You've got me drawing diagrams again :cool:

If I'm understanding this correctly, you are talking about specifying stem length by measuring from steerer CL to handlebar CL at about a 73 degree angle as if measuring a quill stem, and disregarding the actual angle of the stem? Makes sense - I think this would get you very close to the actual horizontal difference in bar location, provided the head tube angle is close to 73. It would be cool to compile a table of popular stem dimensions in this way, as it appears you have already started to do above.

Now can we get back to discussing the aesthetic merits of horizontal top tubes already??

[RPS]

If I'm understanding this correctly, you are talking about specifying stem length by measuring from steerer CL to handlebar CL at about a 73 degree angle as if measuring a quill stem, and disregarding the actual angle of the stem?Exactly mosca. For me it's much easier to visualize the total impact of a stem change without having to go through a bunch of calculations and/or iterations. As long as the vertical adjustment is within the needed range, it’s easier for me, particularly when making big changes as when setting a bike up for someone else to test ride.

Jokes aside, we already use “horizontal” top tube equivalents, so why not stem lengths also?

As to top tube, I prefer horizontal or near-horizontal top tubes, but for functional reasons, not aesthetics.

[mosca]

Last night I got to wondering how a professional fitter handles this issue. For instance, if you determined that a particular rider needed his bars up 5mm and forward 12mm, how do you choose the correct stem/spacer combo to do it? Does it just come from experience? Best guess? And, how can you really dial in the fit when stems are only available in 10mm increments?

Well, the more I think about this, the more I think I'll listen to the voice of experience and begin drinking heavily. Cheers!!

[RPS]

I was assured by an experienced and talented frame builder that if you fix the distance between the saddle and the bars, you can move the rider forward or backwards relative to the BBKT a “small” amount and the rider will not be able to notice the difference.

Assuming he is correct, the most you can be off between standard stems is ½ centimeter, which suggests the saddle would need to be moved less than ¼ of an inch to get the correct amount of total reach. If that is not acceptable, you can fine tune it further by using a different combination of stem angle and spacers, or have a custom stem fabricated.