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Slowtwitch Forums: Triathlon Forum:
Torso vs. Leg length and other fit questions/gripes

 

   


slant

Mar 4, 05 11:05

Post #1 of 9 (1545 views)
Torso vs. Leg length and other fit questions/gripes Quote | Reply

I see a lot of talk on here about "I have long legs and short torso" or "I have short legs and a long torso." How does one know this? I know my inseam and my torso, but is there some ratio that says your long or short in leg? And how does this generally affect bike fitting?

I'm 6'1.5" with a 88.5cm inseam and 61.5cm torso (measure to sternal notch).

I'm looking at entry level tri-bikes - notably the Cervelo Dual and Guru Cron'Alu. According to Zinn's "Complete Guide" (which does have some instructions for tri fitting) I need a frame a seat tube in the range of 56.5 - 61cm and a top-tube length of about 58cm for a steeper angled bike (read "tri-bike").

So, I'm looking at the Dual in "58", it's top-tube is 589 in 75 degree configuration and the Cron'Alu in "59", it's top-tube is 580 in 76 degree configuration. The Dual sounds a little long in top-tube, but I'm just not sure.

Now I'm expecting people to say "go see a bike fitter." The problem is that I have a hard time believing that any bike seller isn't ultimately motivated to "fit" you to a bike that they happen to sell. Now if you can go to BikeSport in MI that apparently sells everything, that's not a problem. But here in SoCal, no one sells everything. TriZombies sells Guru but not Cervelo, Helen's sells Cervelo but I don't trust them and their pushy sales tactics at all.

This sucks.


(This post was edited by slant on Mar 4, 05 11:15)


slant

Mar 4, 05 11:08

Post #2 of 9 (1540 views)
Re: Torso vs. Leg length and other fit questions/gripes [slant] [In reply to] Quote | Reply

BTW, you can read the "this sucks" as "<sigh>this is frustrating</sigh>" :)


Tom Demerly

Mar 4, 05 11:10

Post #3 of 9 (1539 views)
Re: Torso vs. Leg length and other fit questions/gripes [slant] [In reply to] Quote | Reply

There are a few baselines for comparison. Ultimately, now we have enough measurements stored in our NECA Fit Kit Data Base from real customers we have measured we can simply perfrom an arthimatic problem to see the ratio of torso length the leg length to total height.

Once we accumulated enough sets of dimensions then we have a good basis for comparison.

Additionally, puttin the person on the Serotta Size Cycle here in the store helps also.

Tom Demerly
Editor, TriSports University
http://university.trisports.com/


Camel's Toe

Mar 4, 05 11:21

Post #4 of 9 (1523 views)
Re: Torso vs. Leg length and other fit questions/gripes [Tom Demerly] [In reply to] Quote | Reply

Tom, with respect to the Serotta, I was recently fitted on one. When I left the fitting (and I kind of felt ushered out in a hurry, as the shop was closing), I was given all of my "measurements" on a chart of sorts. But, what now? No bike is stock built to these exact measurements. What is an acceptable "range"? Which numbers do I want to insist (on a new bike) stay right in line with the fitting, and which can I say, oh, this is close, and if I change this or that part, I can get to where I need to be, fitting-wise?



Thanks for any help you can give, and feel free to send me a bill


slant

Mar 4, 05 12:23

Post #5 of 9 (1494 views)
Re: Torso vs. Leg length and other fit questions/gripes [slowfathappy] [In reply to] Quote | Reply

Zinn's guide states that Top-tube length is more important that seat-tube. That seems intuitive to me, since a seat height is more easily adjustable than the reach of your handlebars.


MJuric

Mar 4, 05 12:51

Post #6 of 9 (1467 views)
Re: Torso vs. Leg length and other fit questions/gripes [Tom Demerly] [In reply to] Quote | Reply

Couple of questions.

What's a better method. Being fit up on a bike that gives dimensions or setting up the dimensions fo bike and seeing if you fit on it?

The reason I ask is one of my LBS's has a fitter, made by Waterford I believe, that can be set to any mfg'rs specs and you get on and ride it like a trainer.

Also if someone sent you certain body "dimensions" would you be willing to sell them the information on what frame size they'd typically fit in different brands?

Again the reason I ask is that I don't believe that any of my local LBS are particularly suited to fiting people to tri bikes and would like to know that at least I'm getting the right size frame so if fitted improperly I can at least change some things out for a proper fit.

~Matt


Camel's Toe

Mar 4, 05 13:52

Post #7 of 9 (1429 views)
Re: Torso vs. Leg length and other fit questions/gripes [MJuric] [In reply to] Quote | Reply

Now there's a cottage industry for Tom D. You send him measurements, he sends you bike options across price ranges. Based on my post above, you can bet I'm in line for it.



Is it just me or, based on your experience at ALL bike shops, do you think Tom is playing a cruel joke on us? I mean, come on, how many of us don't feel like the shop we go into is looking to sell what is convenient for them (in stock, easily accessible, etc.) in order to maximize short term profit. No "real" bike shop says " let's see what you would fit on" but rather "I have Brand X in the corner, we'll make it fit you." I get the feeling Tom doesn't even own a shop - he just wants us to think that retailers SHOULD act like him.


Jim

Mar 4, 05 20:24

Post #8 of 9 (1378 views)
Re: Torso vs. Leg length and other fit questions/gripes [slowfathappy] [In reply to] Quote | Reply

    
post deleted because the image won't post.

Jim

**Note above poster works for a retailer selling bikes and related gear*

(This post was edited by Jim on Mar 4, 05 20:28)


grant salter

Mar 5, 05 4:46

Post #9 of 9 (1340 views)
Re: Torso vs. Leg length and other fit questions/gripes [slant] [In reply to] Quote | Reply

I would recommend seeing Christopher Kautz in Fairfax. He will do a Serotta Sizecycle fitting and then he can compare those numbers to any other bike geometrys that you are thinking about. Even though he sells Serotta he will give you an unbiased opinion. He does this for a lot of his athletes. He is also the best road,TT, and Tri fitter on the west coast. You can find him at pkracing.com or 415.459.3104.

Grant Salter

www.signaturecycles.com

   
 
 
 



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