Joined: Oct 2005
Posts: 576
Likes: 0
From: between the Popeye's, the liquor store, the funeral home, and the strip club
Bikes: 1992 Miyata Nine 14; 1971 Raleigh Super Course fixie conversion; 2006 Jamis Nova (853 version); 2001 Diamondback Topanga (SS conversion); 1956 Rudge Sports; 1971 Raleigh Competition (processing); 199? Schwinn World Sport (processing)
ken--it could be that because you're running a comparatively large biopace chainring, it has less "differential" in the ovoid than the smaller rings. You might also have a stiffer frame than others (?).
As I posted, on my end, it really was night & day between the 42t biopace and the 43t round ring. My chain was constantly derailing with the biopace, even though I did really like the feel of it, maybe because my frame (185# on a '71 raleigh supercourse conversion) is noticeably flexy, maybe because of the ramped teeth.