Curved crank drive for bicycles and similar has additional shaft with small pulley near crank wheel to deflect chain downwards and better utilize crank lever action

摘要

The crank drive incorporates a holder (3c), a shaft (1a), and small pulley (2b), and a chain (6f). The chain is slightly longer than normal, and passes over the additional pulley for a completely different chain path. The chain traction point has been displaced from a top spot on the crank wheel (4d) to a lower spot (5e), so that the lever action of the crank is fully utilized.