Re: [CR]Lightweight "Woman's" frames. Seat post diameter?

(Example: Framebuilding:Tubing)

In-Reply-To: <E1LGFJ9-0003na-PI@elasmtp-spurfowl.atl.sa.earthlink.net>
References:
Date: Fri, 26 Dec 2008 10:30:01 -0800
To: Mark Stonich <mark@bikesmithdesign.com>, <classicrendezvous@bikelist.org>
From: "Jan Heine" <heine94@earthlink.net>
Subject: Re: [CR]Lightweight "Woman's" frames. Seat post diameter?


At 10:12 AM -0600 12/26/08, Mark Stonich wrote:
>Schwinn Paramount, Cinelli, Colgago, Grandis and I assume others,
>built lightweight "Woman's" frames (not mixtes).
>
>If any of you own one, or have a significant other who does, I would
>appreciate knowing the seatpost diameter. This will tell me the
>wall thickness used in the seat tubes.
>
>It's time to build Jane a new, lighter bike. Since building her 531
>mixte in '80 I have come to the conclusion that the mixte is the
>superior design only when lower grade steels are used. They sure are
>pretty though.

If you want to build a lightweight mixte that offers good performance, you'll have to go with a fully triangulated frame such as that used by the French constructeurs. On those, an extra set of stays feeds the loads from the "top" tube into the rear dropouts.

As you suspect, the mixte that feeds loads into the unsupported middle of the seat tube requires a beefy seat tube to resist the bending loads.

Check out Peter Weigle's article in the "Builders Speak" series of Bicycle Quarterly, as well as the article on triangulation in the same issue.

Jan Heine
Editor
Bicycle Quarterly
140 Lakeside Ave #C
Seattle WA 98122
http://www.vintagebicyclepress.com