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Bike fitting.... a subjective science?(9 posts)

Bike fitting.... a subjective science?Starliner
Feb 23, 2002 11:26 AM
The thread on a newbie seeking advice on a bike purchase, and the strong advice to have a shop fit him, and the several people who seconded the advice.... brought up some questions since I have to confess I've never been fit for any of my bikes.

Once all the data is tabulated, how subjective is the recommendation that follows? Could it differ between fitters? Is a recommendation only as good as the one giving the recommendation? And then how can one be confident that the person giving the recommendation is any good? etc. etc.

With all the different body types, and the many differences of limberness, as well as the differences in riding position preferences (i.e. seat height to bar height; stretched out vs. upright), I would think it would be quite a task to zero in on the "right" choice for somebody brand new to cycling.

I guess I'm just asking for a little more education on professional bike fitting so I can better appreciate the firm point of view that many of us have on the subject.
re: Bike fitting.... a subjective science?TJeanloz
Feb 23, 2002 11:53 AM
Bike fitting is entirely subjective. Strictly by the numbers, most people can ride about 3 different sized frames and still have a good fit. It is the skill of the fitter to match the needs of the cyclist with the fit they recieve.

Too many 'pro' fitters want to put purely recreational cyclists in a flat-backed Chris Boardman style racing position. But most experienced fitters do a better job. They bring years of experience into play, and their job is mostly to listen to what the rider wants, and make recommendations based on that. The recommendations are based on the years of experience and thousands of fits done. The fitter tends to profile people, so you have a baseline fit, which is accomplished arithmatically, and then you adjust it to meet the profile of the rider. So you have a racer who's had back surgery, you take the racer baseline, and adjust the handlebar height and reach.

It is entirely a subjective offering and a true fit is not done on a size cycle by the numbers- but on your own bike by somebody with a lot of experience.
well saidgtx
Feb 23, 2002 12:16 PM
I think another thing that often doesn't come up in these fit discussion is the person's current bike. That is usually a great reference point/starting point. You need to know what you like and dislike about your current setup before you can make an informed decision about your new ride. And often a few small tweaks to someone's current bike can make a huge difference.
Yup - gotta listen to the rider, not just measure him/herRay
Feb 25, 2002 6:59 AM
For a really good discussion of bike fit and the tradeoffs involved in differ positions, check out Peter White's article on fitting:

Gives more detail on what TJeanloz said above. Probably a useful read for anyone who's thinking about buying a bike but doesn't know exactly what they need.

Subjective, yes...Elefantino
Feb 23, 2002 12:06 PM
A few years back, I went to a Cannondale dealer. I was "fit" for a 63 cm; they had a R800 in that size. Went to a LeMond dealer, was "fit" for a 61; they had a Buenos Aires in that size. Went to a Schwinn dealer, was "fit" for a 60 cm; they had a Peleton Pro in that size.

When I went to the Trek dealer, they had a 60cm 5200 in stock. They fit me and told me I'd be better off on a 62cm. I tried the 60, then came back the next day to try a 62 that was one of the wrenches' personal bikes. I ordered a 62.

Who was honest, and who was not? I don't honestly know. Were the numbers different because each bike had a different geometry (except the Trek and the LeMond; they were the same)? Or were the numbers different because the shops had large-size bikes in stock that they needed to dump?

Again, I don't know. According to, I'm a 62.

EXTREMELY SubjectiveScummer
Feb 23, 2002 1:02 PM
I measured myself, and had others measure me extensively before I orded a bike (Litespeed Classic)
from Colorado Cyclist. I also talked extensively to CC personel before ordering. I ordered a 59, got it and worked for over a month trying to get it to fit. Never did, sent it back for a 61. CC was great in accepting
it and replacing it with a new frame.

Don't fall for "racer" fits. The vast majority of us want a comfortable ride. Note what Rivendale has to say,
it is very subjective and the "fist full of seatpost" showing...That's great advice for most of us recreational iders. I think.
all models not measured the same...C-40
Feb 23, 2002 1:36 PM
The 63 Cannondale is measured center to top, the Lemond is measured center to center, the 62 Trek is measured to the top of the seat tube collar. All of these were very close to the same size (vertically).
I was getting fitted for a bikeBarnyard
Feb 23, 2002 2:47 PM
in Sommerville Boston at Independent Fabrication. They took measurements and punched them in a computer program. I was told that there method of sizing was something worked out pretty intensively. They took my inseam, stand over measurement, and arm measurements. When they were finished computing, they gave me recommended angles, stem length and suggested frame size. They then matched me up to the frame that had these same angles.
However I could have easily picked the frame size just by standing over a frame that gave me decent clearence. By this I mean, not just over an inch but at couple inches or more.
so does it fit?merlinguy
Feb 23, 2002 3:58 PM
well? after all that did you buy a bike and does it fit?