Lou, the someone is probably me. The idea as I see it is to find the center of the crank axis and measure backward from that. I think that is the convention used by a number of builders, at least Trek. I think it is also implicit in the Colnago build drawings that are n the webTo get that center you can eyeball the center of the crank axis, or measure to the near and far edges of the BB shell and average the two values. The averaging method should be more accurate, since you're terminating the measurement on hard edges rather than a point eyeballed in space. I use the BB/eyeball on built-up bikes, and the shell edges method on bare frames.
Ken Freeman Ann Arbor, MI USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of LouDeeter@aol.com Sent: Sunday, May 20, 2007 8:34 PM To: classicrendezvous@bikelist.org Subject: Re: [CR]Was: intro... now: frame geometry
Someone said:
> I tend to like the stay intersection method for both chainstay and
> wheelbase, but that's really just because it gives me a way to find
> the me
asurement
> point, and to be consistent in my own work.
>
I'm still a bit confused by this discussion. I think I "get it" for the measurement of the chainstay to the point in the dropout where the seat and chainstay centerline meets. But, where to measure at the bb? I read one account that says to measure to the center of the bb shell (crank). I have also measured to the edge of the rear round edge of the bb shell, not the center.
Lou Deeter, Orlando FL
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