MIN 

Does anyone know what the average male inseam-to-height ratio is?
Do manufactures set geometry with this proportion in mind?

My measurements:

70" (177.8cm) Height
32.25" (82cm) Inseam
-------------
46.1% Inseam to Heigh Ratio

I want to know - relative to the male norm for my height - is this short legged or long legged?

Based on the answer to above, which company's geometry would suit me? (Example: I know Lemond is good for relative short legged riders, but I'm not sure what that is, quantifiably.)

5Biker

FWIW;
height 72"
inseam 34"

47.2%

ILUVUK

height - 69 inches
inseam - 31 inches

44.9%

531Aussie

there's an old thread about this with several measurements

https://www.bikeforums.net/showthread...ghlight=inseam

there are others, too, if you wanna search

I'm 182cm with an 89.5cm inseam

NOT PANTS INSEAM!!

Some of you Yanks seem to get pants inseam and real inseam mixed up

MIN 

Thanks for that link.

However, I wanted to know if there was a more authoratative source than individual contributions. Individual responses are nothing but statistical noise. It would be useful, though, to know what the aggregate view is. Hence my post.

Reynolds 

Height = 173 cm
Inseam = 83.5 cm
48.3 %

MIN 

OK - again, I'm not soliciting your measurements. There are many other threads along those lines.

FrankBattle 

but why?

There are so many other aspects to bike fitting. Throw this measurement away if you are after a good fit. Invest in a $75+ professional fitting at your [recommended] LBS and go from there.

Bike companies may well do this, but I have never heard of it.

MIN 

I realize there are other aspects to fitting however no LBSs that I know of offers a good fitting. It's mostly intellectual ************ - plus I'm curious.

I already know the tight window as to my size. Mostly, I'd like to know the tendency of manufacturers to cater to certain proporations (as in the Lemond example I used earlier.)

Blopslee

check out the charts at the bottom - seems he's had years of experience

https://www.prodigalchild.net/Bicycle6.htm

FrankBattle 

Ah yeah. I understand intellectual curiousity. Stab in the dark here, but you could just try emailing the technical departments of whichever bike company you are interested in .. Worst possible answer is "no." No?

MIN 

Interesting insight from that link:

The way I determine frame size is to start by saying this equals two-thirds of the rider’s inseam. (This is a starting assumption, other factors need to be taken into consideration.) This means that for the taller the rider, the amount of seat post showing out of the frame increases progressively. The resulting difference in the handlebar to seat height ratio accommodates the taller rider’s longer arm length. The handlebar stem also increases in length for a larger frame. The top tube length on larger frames increases at a lesser rate, because the upper body length increases at a lesser rate.

Because you guys respond quicker. Isn't that the purpose of an Internet forum? To share ideas and filter out the sh1t?

Blopslee

[QUOTE=MIN]Interesting insight from that link:

[I]The way I determine frame size is to start by saying this equals two-thirds of the rider’s inseam.

I think things were thought to be a little more clear before sloping top tubes.

biffstephens

Height 188 cm
crotch 84 cm
trunk 73 cm
arm 79 cm

44.68 %

glenng

+1

grebletie

height 68 inches
inseam 33.5 inches

49.2%

lots of leg there.

terrymorse 

Height: 71"
Inseam: 35"

49.3%

Twins separated at birth?

bruce19

Those are exactly my measurements. And, I mean exactly. I've found that I can fit nicely on frame sizes from 54-56 c to c for general recreational road riding.

FrankBattle 

Depends on the topic.

You asked a specific question (relating height/inseam with frame size) to which you will get a myriad of answers since not everyone is riding the right fit bike. To get a specific (or reliable) answer, you need more than forum answers. Besides, people probably lie about their inseams and/or height. Imagine that.

branman1986

why would people lie about their inseams and height?

biker7

Don't know if you have a background in statistics or not. Bottom line is inseam length (independent of height) still dominates for the vast bell curve of cyclists out there. There is a correlation however. Dave Moulton's chart is derived by thousands of fittings and he is a pre-eminent expert on the subject. So is Sheldon Brown. Both subscribe to the 2/3 X's cycling inseam for frame size. I do too. Statistically most (not all) derive their height in their legs. Tall people many times have pedestrian length torsos. This applies to Sheldon Brown and myself and countless others. As a result, bicycles are designed to grow vertically almost 2:1 versus horizontally in frame size. This is not happenstance but based statistically on a normal distribution of height to inseam ratio. The reason that seat tube length or now virtual seat tube length with the advent of sloped top tube geometry bikes predominates is because virtual or actual seat post length dictates head tube length. In the grand scheme it is the ratio of seat post to head tube length that matter for saddle to handlebar drop. The other prevailing factor is top tube length and again, top tube does not increase nearly as must as seat post and head tube length between frame sizes which agrees with the statistical norm that torso size does not change nearly as much as inseam for different size people.
HTH,
George

branman1986

I'm tall and my inseam is 50% of total height, seems to reflect what George said.

FrankBattle 

This is a rhetorical question, right?

grebletie

I'd be interested to know why someone would lie about their inseam. Correct inseam measurement is integral to a good fit. Why fudge the numbers, and thus the fit?

badger1

Here's the ratio I recall reading a while back in something by a sports doc (it was cycling-related): for males, dividing total height by true (cycling) inseam (bare feet/floor to pubic bone) will typically give a number somewhere between 2 and 2.2. 2 is long legs, 2.2 short (both relative to total height). My case: 174.5 t/h, 84 cm inseam gives 2.07, so tending slightly toward 'long legs for height/short torso.'