Re: [CR]Bike fit, was Q factor

(Example: Racing:Wayne Stetina)

From: <gpvb1@comcast.net>
To: classicrendezvous@bikelist.org
Subject: Re: [CR]Bike fit, was Q factor
Date: Fri, 07 Jan 2005 20:14:35 +0000


Date: Fri, 7 Jan 2005 13:58:59 -0500 From: marcus.e.helman@gm.com To: classicrendezvous@bikelist.org, tsan7759142@comcast.net Subject: [CR]Bike fit, was Q factor

I think Tom raises an interesting question. I am getting less willing to deviate from what I think is my correct size. I have one bike that is 2cm bigger, and although I can ride it, stepping forward when I stop is something to be done with some care.

Something close to the correct relationship of feet, hands and butt can be acheived on range of different sized frames, yet some bikes seem to fit better than others.

Is it better to have a long top tube, or a long stem? You could get your hands to the same point in space either way. Ditto a long seat tube vs. long seat post.

In any case, restricting oneself to bikes that really fit does put some items in the eBay candy store off limits. I have decided that I lack the time, money and storage space to own bikes, no matter how beautiful or historically significant, that I am not prepared to ride for at least half a day.

Complicating all of this is the fact that even when a bike is advertised as 53cm ctc, it has been measured in someone's basement on Sunday evening, as the guy was composing his ad. His measurement may not have been all that accurate to begin with. I have read plenty of accounts here about bikes that were not the size their new owners expected.

Marcus Helman Huntington Woods, MI Two thoughts: First, remember that proper frame sizing (for the individual) depends on geometry, and as Jan's post (and others) have touched upon, what you probably want is consistent standover height. BB height and ST angle can influence standover significantly. I always ask eBay sellers for the standover height of a frameset whenever possible. It can clear up frame sizing / fit questions in most cases. I typically ride a 59-62 cm size (c-t). depending on the other design parameters of the frame, as well as as how I want to use it. (Chuck I envy you, you 50th percentile doode! I'm about 95th Percentile)! Secondly, frame size and TT length limit things. Frame size limits handlebar height, so you can't just put an MTB post on a way-to-small frame and get it to fit with a "typical" stem (although a Nitto Technomic can help fix that). Your handlebars will likely be way too low at their max. height on that small frame, otherwise. Similarly, TT length and stem length interact to affect how the bike "feels" during steering inputs. Shoot for a TT that give you a fit that you like with about an 8-12 cm. stem if possible. I wouldn't want a bike that I had to put a custom 6 cm or 16 cm stem on to use, as I don't think I would like the handling "feel" of the resulting bike.....

Greg Parker
Dexter, Michigan