US Patent 10155566 Interchangeable bicycle sprocket

A bicycle sprocket is provided. The bicycle sprocket has a rotational center axis and includes a first shifting facilitation area configured to facilitate a first shifting operation from a first sprocket toward the bicycle sprocket, and a second shifting facilitation area configured to facilitate a second shifting operation from a second sprocket toward the bicycle sprocket. The first tooth number of the first sprocket is different from the second tooth number of the second sprocket.