Jenifer

I'm looking to buy a bike -- my first "real" road bike, though I have several thousand miles' experience on my current 17-year-old bike -- and I'm trying to understand something about bike geometry and fit.

The first new bike I tried was a Specialized Dolce Comp, 51 cm. I loved it! It fit well and was incredibly fun to ride, but it was the first; any modern road bike would have been an eye-opener. Subsequent bikes at that shop did not feel as good.

But the owner of my local LBS wanted me to try some of the bikes he had. A Schwinn Fast Track Comp, XS, seemed like it would fit. I prefer Specialized to Schwinn based on personal experience, but to humor him, I tried it on the trainer. Did not like it. He said it looked like it fit, but no matter how we adjusted it -- seat, stem, handlebars -- it didn't feel right. My upper body felt too stretched out. (Yet on each upstroke, it felt like my diaphragm was being compressed too much, which can't be good for breathing.)

So we looked up the specs. In almost every relevant measurement, the Schwinn is smaller! TT length is shorter, and of a comparable angle. Why did I feel more stretched out? Is my brain playing tricks on me because I'd rather have the Dolce? If I get the Dolce, and find out that I only thought it fit, that's an $1800 mistake.

This frame-fitting thing feels like black magic. I know, I know -- go with the one that feels best. But our minds can fool us when we're already biased towards a particular outcome, so I'm suspicious of my own judgment... Call me a geek, but I want to be able to explain this.

SadieKate

Just curious. Did you actually measure the reach to the hoods? The bars and the brake hoods could make the reach longer also. Or having more of a drop from the seat to the hoods will effectly lengthen the reach. And then sometimes, it just doesn't feel right so it isn't right.

Did you actually get the ride each bike or just use it on the trainer?

fogrider

no need to rush into it...go back and ride it on the road. find a hill close by and take them up and down. be sure to put it through the paces...shifting, braking, spining, hard accelleration, etc. put your hands on the tops, hoods and drops and see how it feels.

AnthonyG

Sounds to me like the Schwinn had longer cranks on it than the Specialized and this makes a huge difference to comfort and feel. Or a different seat tube angle (big can of worms here.).

Here are my favorite references on bike fit, https://sheldonbrown.com/frame-sizing.html and https://www.cranklength.info/ (read the start of the first article and check your inside leg measurement in the crank length calculator)

Also a 1 degree difference in seat tube angle makes a big difference.

To get good fit your first need to find your correct crank arm length, then you need to set your saddle so you have KOPS as a starting point and then you need to see where your reach naturally falls.

This works well for custom frame building but with factory bikes there are all sorts of compromises.

Anyway please read the references so it makes more sense. Feel free to ask more questions after reading the articles.

Regards, Anthony

MichaelW

Read
www.peterwhitecycles.com/fitting.htm

When comparing bikes, I avoid the problems of different frame angles by using [x,y] coordinates, with the origin [0,0] at the bottom bracket.
Two bikes may have identical top tubes, but one may have a slacker seat-tube (ie more length behind the BB, less ahead). When you slide your saddle to the correct position relative to your pedals, the slacker angle frame now has a shorter reach!

If you have been riding for a long time, and know what your riding position is, make the bike fit you, not the other way around.

samp02

A good bike fitter is like finding a good MD..........invaluable.

Retro Grouch 

Check out the difference in handlebar height. To me the drop from the saddle to the handlebar is a key dimension and lots of people completely overlook it. The easiest way to measure is to measure from the handlebar and from the saddle to the floor and take the difference. If the Schwinn has a shorter head tube, the handlebar might be significantly lower. That would explain your breathing issue.

Stjtoday

If your lbs is not taking full measurements of your body and determining your needs in a frame, I would find a new lbs.

Inoplanetyanin

I think that the sense of comfort on the bike is mainly subjective. There can't be precise rules predicting and guaranteeing how a particular bike will feel.

In my experience, if you like the feel of the bike right away, it will stay that way for a long time, and vice versa, uncomfortable bike will not become comfortable (disregarding getting used to it).

Who is pushing you? Get the one YOU really WANT.

Jenifer

It certainly would, and that's what I think is happening with the XS Schwinn frame -- it's actually too small. The seat is pretty far above the handlebars. I'll try one frame-size bigger and see if it helps.

Test-riding the Schwinn(s) will be possible this afternoon (it was raining last time I was in the shop), so I'll do that. On the other hand, I just test-rode the Specialized again at a different shop, and once again, I loved it. Felt like I was flying; couldn't wipe the grin off my face! I think I know what my choice will be...

Thanks for the bike-fitting pages everyone posted. Those have been helpful!

H20.1

The best source on Bike Fitting Ive found is a book put out by Greg LeMond back in the 80s. Some items are a little outdated but his guidelines on fit are outstanding. They are used by many professional fitters and developed by his French coach when he was racing with Peugeot.

Using his method and a few simple measurements you can fit yourself. And the best part is that it WORKS. He was a big name so any library should have a copy of the book.
I like Peter White's site too but the problem I have with his methods is that too much is done simply by feel. Using LeMonds book I was able to get a position on the bike that was more aerodynamic yet very very comfortable (two things I thought didnt go together well).