Re: [CR]ebay elliptical chainring

(Example: Framebuilders:Alberto Masi)

Date: Tue, 04 Dec 2007 13:40:14 -0500
To: <Classicrendezvous@bikelist.org>
From: "John Betmanis" <johnb@oxford.net>
Subject: Re: [CR]ebay elliptical chainring
In-Reply-To: <20071204171851.23756.qmail@server291.com>


At 05:18 PM 04/12/2007 +0000, Emily O'Brien wrote:
>Actually, you can use a biopace ring on a fixed gear, and I bet you could use that one too, assuming it' symmetrical.
>That's because at any given time, the chain is wrapped around half the teeth of the ring, no matter what position it's in.
>

Yes, I figured that out also. However, as Sheldon states in his Biopace article, there will still be some variation in chain length on the straight runs between when the axes of the ellipse are vertical and horizontal because of the angle. Incidentally, the two extra holes in the elliptical chainring shown on eBay are probably the foci of the ellipse. http://en.wikipedia.org/wiki/Ellipse

John Betmanis
Woodstock, Ontario
Canada