Abstract: A crank assembly for a bicycle uses a plurality of auxiliary sprockets and chains to achieve high ratios of wheel speed to pedal-rotation speed. The compact crank assembly is especially well suited for use on full-suspension bicycles, as high gear ratios are attained without altering the normal size and layout of the main sprocket and drive chain of the bicycle. The auxiliary sprockets may be coupled by a simple axle or, alternatively, may be coupled by a rider-adjustable transmission to provide greater control over the gear ratio of the crank assembly.