Originally Posted by genejockey

I have kept the Biopace chainrings on my 1989 Schwinn Circuit, because like the Sante groupset on it, it's part of the bike's original equipment. I tried it in the original configuration, and I noticed a 'surge-y' feeling when going up a 2-3% grade. I currently have both rings rotated one spider arm clockwise, which makes the orientation more like the current thinking on oval chainrings, and I don't notice the same feeling, though of course this is totally subjective. But I'm leaving it like this.

I just picked up a 1985 Centurion Ironman that also has Biopace chainrings, so I'll experiment more when I'm finished with the rebuild.