Is women's specific geometry a myth?

Triathlon Forum
1

I’ve heard it both ways. Paraphrasing:
Cervelo: at a given height, women have the same proportions as men. “Women’s specific” geometry is a marketing gimmick.
Trek, Specialized: at a given height, women have smaller hands, narrower shoulders, shorter torsos, and longer legs. Therefore, they need proportionately shorter top tubes, narrower handlebars, and shorter-reach levers. In ST parlance, women would be more likely to fit taller and narrower than longer and lower. Or you might say, women are more stacked.

So, how about this: I made a quick survey where you can enter your sex, leg length, height, shoulder width, hand size: http://www.surveymonkey.com/s/RSTHNLT

After I get 100 responses (or after responses quick coming in), I’ll crunch the numbers, look for size and statistical significance of male/female differences controlling for height, and post results back to this thread. I’ll also post the table of individual results. On the survey you can enter your ST username or any other pseudonym if you want to be able to identify yourself in the table, or you can leave it anonymous. And I’m not using this for anything other than posting back here–no school project or company research or anything.

I wouldn’t exactly recommend that anyone go to market with this self-selected sample of ST readers (assuming anyone responds at all), but it seems like a fun way to shed some empirical light.

If you complete the survey and think others are interested, give this a bump so it’ll stay up long enough to get some responses.

2

I’ve heard it both ways. Paraphrasing:
Cervelo: at a given height, women have the same proportions as men. “Women’s specific” geometry is a marketing gimmick.
Trek, Specialized: at a given height, women have smaller hands, narrower shoulders

Cervelo says that too

, shorter torsos, and longer legs.

Does treks WSD geometry back up that claim? or is the same? or just less aggressive?

the stack and reach for the madone 5.2 WSD and non WSD is the same in both sizes 50 and 58

didn’t check the rest

3

Cervelo is full of rubbish. Yes, there are outliers and variations within a range, but Trek and Specialized and everyone else making WSG bikes is correct that there is typically a difference in proportion between men and women. That said, I’m not saying all WSG is better than standard geometry in a bike. I have seen plenty of horrible WSG that makes me wonder what the heck the designer was thinking. But then again, Cervelo geometry makes me wonder what the heck they were thinking…

4

It’s a myth. Proportions are, more generally, height based. Short people have more in common with each other, typically, than women have in common. A 5’ man and a 5’ woman are statistically more likely to have a similar build than a 5’ woman and a 6’ woman.

Looking, for example, at clothing will give you a false sense because of how clothes are cut to fit. Women can, comfortably, wear their pants up against their crotch. Men have “something in the way there.”

But, really, women’s specific geometry is, IME, the byproduct of a single OVERWHELMING factor - pressure on a woman’s vagina is a MUCH bigger problem than pressure on a man’s taint. And most women’s saddles really suck. So women tend to sit on the back of the saddle, on their sitbones, which means they sit both back AND up, which of course shortens the reach tremendously.

Add in the fact that bike makers won’t make 650c wheeled bikes for women introduces serious toe overlap issues that must be accounted for which further complicates things.

My experience - put a woman on an Cobb V-Flow or ISM, and the resulting geometry will be “normal.”

5

We’re going to find out. I just bought a V-flow plus for my wife. Last I heard, she had a V-Jay-Jay. I wouldn’t know. I’m too busy training.

6

Do you have data to back up your claim?

If trek is “right” why does the WSD madone have the same stack and reach as the mens?

Cervelo is full of rubbish. Yes, there are outliers and variations within a range, but Trek and Specialized and everyone else making WSG bikes is correct that there is typically a difference in proportion between men and women. That said, I’m not saying all WSG is better than standard geometry in a bike. I have seen plenty of horrible WSG that makes me wonder what the heck the designer was thinking. But then again, Cervelo geometry makes me wonder what the heck they were thinking…

7

from the perspective of bike fit, only inseam versus overall height will determine a bike’s geometry. unless it can be demonstrated that women, or women below 5’6" have, in general, longer legs than men below 5’6", then there’s no reason to make a women’s specific geometry. there’s plenty of reasons, however, to make geometry specific to people of both sexes who’re shorter than 5’6".

now, brake levers, that’s another story. but cervelo isn’t denying that smaller people have smaller hands. while bike frames descend in size, brake levers are all the same size, until and unless you place a short reach lever on a bike. so, don’t mix up components like brake levers with frame geometries.

8

WSD:

http://www.sparta.nl/Pics/Dynamic/Collections/2011/Sparta%20Tyros-Blackline-dames-D-L1.jpg

MSD:

http://www.sparta.nl/Pics/Dynamic/Collections/2011/Sparta%20Tyros-Blackline-Heren-H-L1.jpg
.

9

When I was racing bikes (before any women-specific bikes except some Terry’s) women raced on men’s bikes. What was noticeable was that women generally used shorter stems than the men by about 20mm on average, pretty much regardless of frame size. This may be, as Rappstar suggests, a function of saddle position (though almost everyone was using the euro-slack “LeMond” setup in those days), but it seemed anecdotally clear that women needed shorter top tubes than men in any given frame size (at least in a road geometry).

Bottom line though is to get a bike that fits you. There is probably more variation between brands on stack and reach than between the men’s and women’s models in a given brand. Also with the development of compact geometries and (more importantly) extremely expensive frame molds for carbon bikes; many manufactures have “discovered” that you don’t need frames sized in 1-2cm increments and can just shoehorn everyone onto a S,M or L.

10

I thought women’s specific was the pink frame.:slight_smile:

I’ve read both arguments. However, there are some long legged/short torso men and short leg/long torso women in this world also, so I’m a little skeptical in some ways of “women’s specific”. I think foremost you have to buy a frame based upon your own personal body dimensions, male or female.

11

until and unless you place a short reach lever on a bike. so, don’t mix up components like brake levers with frame geometries.
Ok, fair correction, but it’s still true that often enough a women-specific ‘design’ bike will feature both a slightly different frame geometry (at least on the cut-and-weld tube bikes) as well as a component package featuring a women’s saddle and short-reach levers. I quite agree with you, I think: I’ve often thought that shorter-reach levers would be useful to most people who fit on a 48cm bike, male or female, and that your typical 6-foot tall woman can reach regular levers just fine. But, my point here was to see if we could gather some community data to see if we could demonstrate that women do or do not have longer legs than men of the same height.

I know Jordan has access to a fine database of fit coordinates (and that he’s a careful thinker), so I assume when he says there’s no difference, he means he’s seen empirical evidence so indicating. Most of us haven’t.

However, his point that proportions are more a function of overall height than gender wouldn’t necessarily contradict a within-gender variation.

For example, consider this (completely fabricated) data set: seven men from 5’10 to 4’10 whose inseams and heights are (34.5,70; 32.5,68; 31,66; 29.5,64; 28,62; 26.5,60; 25,58). Seven women in the same height range have inseams and heights as follows (35,70; 33.5,68; 31.5,66; 30,64; 28.5,62; 27,60; 25.5,58).

Now, the ratio of inseam:height varies more with height than with gender (I made the data do that because I believe Jordan). But still, there’s a significant long-leg effect for women (I made the data do that to prove my point). You could even model it (Men: inseam = .005height^2 + .14height. Women: inseam = .005height^2 + .15height) I.e., in general taller people have proportionately longer legs, but across all heights, on average women’s legs contribute an additional 1% or so of height. I’m not saying this is the case in the real world, or that it makes enough of a difference to legitimately influence bike-making, just that it could be true, and I haven’t seen data to demonstrate it one way or the other. And judging by the rate of return on my survey, I’m not going to :slight_smile:

An interesting corollary to Jordan’s point though–if the inseam/height ratio varies with height, that suggests the ‘consistent fit theme’ across a manufacturer’s size range (which you so nicely illustrate with those graphs of Trek’s speed concept sizing), might ideally bend a bit rather than be linear. And if the variation is in the direction of taller people having proportionately longer legs, it would suggest that shorter people are even more likely to need long (relatively) and low bikes, hence all the more reason for 650c wheels.

12

Sometimes the color really is all there is to it! But as to your point–I totally agree. My wife, for example, is five feet tall, with short legs and a long torso, and she nearly always buys bikes in the smallest size there is so she can climb over the top tube, and then upsizes the stem.

13

now, brake levers, that’s another story. but cervelo isn’t denying that smaller people have smaller hands. while bike frames descend in size, brake levers are all the same size, until and unless you place a short reach lever on a bike. so, don’t mix up components like brake levers with frame geometries.

http://moto-madness.com/catalog/images/CRG%20levers.jpg

They’ve had them for years for sportbikes, which are under much greater stress. Not sure why they aren’t available for bicycles. I installed a set on my wife’s SV650S. She has tiny hands, but these work great for her, and the brakes function normally.

14

just for reference, this is the stack and reach of the Cervelo S3 across their sizes. Not exactly linear, but close. Different slopes for stack and reach though.

http://www.slip-angle.com/sizes.png

15

Well, this is an interesting point. In their aluminum-framed bikes, Trek’s WS bikes are taller and narrower–e.g., look at a 50cm Lexa (women’s model) vs a 50cm 2.1. The women’s bike shows a stack and reach of 54.2, 36.8. The 2.1 shows 53.5, 37.4. Lower, longer. But it’s easier to cut a tube a different length than to make another mold for a carbon bike. But really, the differences are so small, it really doesn’t seem necessary given that gender-related inseam/height differences (if they exist at all) are unlikely to be large compared to individual variation, and in any case can usually be adjusted for easily enough by going up or down a bit in stem length.

16

sounds to me like Trek has it nailed:

on the cheaper bikes, make the Womens Specific Geometry wimpy, for comfort.

On the hardcore bikes, make the bikes correctly.

=)

Well, this is an interesting point. In their aluminum-framed bikes, Trek’s WS bikes are taller and narrower–e.g., look at a 50cm Lexa (women’s model) vs a 50cm 2.1. The women’s bike shows a stack and reach of 54.2, 36.8. The 2.1 shows 53.5, 37.4. Lower, longer. But it’s easier to cut a tube a different length than to make another mold for a carbon bike. But really, the differences are so small, it really doesn’t seem necessary given that gender-related inseam/height differences (if they exist at all) are unlikely to be large compared to individual variation, and in any case can usually be adjusted for easily enough by going up or down a bit in stem length.

17

or that :wink:
.

18

I also said that some people have rubbish “Women Specific Geometry”…

I would concur, that for a given top tube length that women typically need a taller seat tube/head tube. (The converse of what Titanflexr said.) This is based on fitting a number of women to bikes and building a number of custom bikes for women over the years. For men’s bikes the point where top tube and seat tube are relatively equal lengths tends to be a 56 or 57cm frame. For women this should be a 52 or 53cm frame - in general. Part of it has to do with hight distribution (women are typically shorter than men, so the size that the average man rides is bigger than the size that the average woman rides) and part is due to body proportion.

19

and part is due to body proportion.

ok so it continues.
some people are continued to believe proportions are different.

I am scouring the innerwebs for data, I know this thread is polling for some but it will not be enough, and not controlled enough to answer the question.

who has data?

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ahem, n=0 at the moment. I can take it up to 2.