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/
John Betmanis
Woodstock, Ontario
Canada