Re: [CR]Frame Alignment Obsession?


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From: "Jon M. Schaer" <jschaer@columbus.rr.com>
To: "garth libre" <rabbitman@mindspring.com>, <classicrendezvous@bikelist.org>
References: <000a01c1881e$3f4ea680$0ab256d1@Marta>
Subject: Re: [CR]Frame Alignment Obsession?
Date: Wed, 19 Dec 2001 01:09:31 -0500


----- Original Message -----
>>> When I got home and put the wheel on frame it still was a shade off from having the rear wheel centered under the brake bolt of the bridge. It is a shade over 1 mm off. Others can not see it, as 1 mm is such a small difference. Finally I just took a ruler and measured the distance from the center of the braze on bolt holder to the inside face of the seat stays and there was the 1 mm difference.
>>>

By that description it sure sounds like the bridge is off. It is possible that, though the hole is not centered between the seat stays, that it is on the center plane of the frame. But in this case, the wheel would probably look correct at the hole, but closer to one seat stay. This condition could be checked on a frame table, or with a surface gauge and some long indicators, off of the BB shell faces.

Either way, I honestly would not hassle over a 1mm vertical lean error. I would use no-hands riding as the guidepost. You can detect pretty subtle errors, but it depends on where the error is, and rear wheel lean doesn't stand out much. I've seen more error than that on many big-name carbon forks, and the owners couldn't even tell.

Jon Schaer
Columbus, OH