Originally Posted by
CharlesC
I keep reading about compact cranks. Could someone please tell me what that means?
The current norm for Bolt Circle Diameter (BCD) in a full size double crankset is 130mm. Typically, you'll see gearing like 53/39 on these. You can go as low as a 38t chainring on such a setup. On a compact double, the BCD is 110mm, and the typical gearing is 50/34-