Re: [CR]steering geometry


Example: Framebuilders

From: "Jon M. Schaer" <jschaer@columbus.rr.com>
To: "dave bohm" <davebohm@home.com>
Cc: <classicrendezvous@bikelist.org>
References: <20010521.162610.-266283.11.richardsachs@juno.com> <3B098973.7195835B@fridayscomputer.com> <3B0A1A52.79B5@adnc.com> <003d01c0e2d9$ecba8040$56f90541@tucson1.az.home.com> <006301c0e319$bbd8a980$700b1841@columbus.rr.com> <002801c0e327$a2955820$56f90541@tucson1.az.home.com>
Subject: Re: [CR]steering geometry
Date: Tue, 22 May 2001 23:40:29 -0400


----- Original Message ----- From: dave bohm <davebohm@home.com
> I agree that this may be the case with a retrofit of an kestrel ems to an existing > bike frame that was sized for a typical steel fork but what I was getting at is
> that some companies still produce bicycles with steep head tube angles and
> 45mm rake forks which produces a very low trail measurement.
>

I'd assume anything except a custom would qualify as a retrofit, though the bike may have come from the "factory" with the Kestrel fork. Kestrel used the 45mm rake specifically because of the crown seat height issue, wanting their forks to be suitable for substitution with the largest number of bikes, and 40mm is probably the most common stock rake.
>
> A good example is ummm-TREK. Now I may take some slack for this but
> they are a perfect example of poor steering design. OCLV's across the
> board have trail measurement from 51mm to 53mm. While most of our
> beloved classic bikes have trails in the 55 to 60 range. I don't even know
> how Lance really does it on that thing or does it just show how we can get
> used to practically anything. Most of the time it would be fine but I wonder
> how it does at very high speed descents.
>

Couldn't agree more about the Treks, but I suppose it is subjective. I noticed that the OCLV Lemonds came with the a Kestrel fork instead of a Trek fork, which would help rectify the trail problem, though the end-result gives credence to the Sachs argument of there being more elements to the picture; I still thought even the Lemond OCLV handled poorly. I don't know whether Lemond wanted the Kestrel spec'd because of true handling preferences, or just marketing reasons (or both).

Interestingly, a very well-respected east-coast shop owner and fit-guru told me that L. Armstrong only rides the OCLV's in races and photo shoots, etc, for obvious contractual reasons. He actually doesn't care for the bikes. His training bikes are supposedly of a certain Italian make. Although the frames Postal rides are stock geometries, I'd imagine the forks could all be custom made for the team, allowing for some method of correction. Of course, they also benefit from proper fitting.

What I still find utterly amazing is how several bikes with what appears to be only the subtlest of variances in geometries still manage to have pronounced handling characteristics of their own. I certainly don't believe that there is a "utopian" perfect geometry to strive for, there are definately some characteristics that seem to me to more than just subjective. I'd guess, for example, that any major pro team bike is a proper all-around handler, because it needs to be to get the job done. If I rode each for 5 minutes I'd probably like some more than others, but if I rode each one at a time for a month, I'd probably adjust to each and determine it competent. But there have been a few bikes I've had for a while that I never fully adjust to. They are just "off" a little in some murkey way.

It's funny that, considering that any builder can make a frame any way they choose, that there seems to be (at least, used to be) a large commonality among nationalities. Italian bikes seemed mostly one way, French another, British another. I suppose builders are their father's son, in essence, and a particular philosophy propogates through training and apprenticing.

Just for reference, I personally have found my '84 Pinarello to be my best handling bike, so far. I had a too-small Landshark that I liked the out-of-saddle climbing balance better, but it was a poorer decender. My Torelli is a close second, overall.

Jon Schaer