Revolutionary implementation of a planetary geared crankset and an exciting category of cycling. Provides a 1.6 to 1 gear ratio and shifts instantly under any load. Features die cast alloy crank arms and external bearing bottom bracket. Compatible with most conventional frames. Frame requirements: fixed chainstays no ISCG tabs 68mm bottom bracket width and down tube cable routing. 8/9/10sp - Compatible with any twist or STI style of shifter - Not included. 68mm Patterson specific bottom bracket included