Joined: Jan 2010
Posts: 9,808
Likes: 1,776
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
I like 'em, but another thing about BioPace is the size of the smallest sprocket that will fit on a 110mm, 74mm or 130mm bolt pattern.
Original BioPace rings were limited to a smallest size of 28t, 38t and 42t for the 74, 110 and 130mm bcd's, respectively.
The newer BioPace-II, -HP and -SG allowed a smallest size of 26t, 36t and 40t, respctively, and so were then immediately offered by Shimano.
Round rings allow a smallest size of 24t, 34t and 38t, respectively, for Shimano's primary three 1980's bolt patterns.