US Patent 9914502 Detachable chainring assembly

A detachable chainring assembly includes a first chainring, a second chainring and a locking part. The first chainring includes a first through hole. The second chainring includes a first surface, a second surface, a driven hole, and a plurality of first protrusion parts. The second surface is opposite to the first surface. The driven hole runs through the first surface and the second surface for securing a driving portion of a crank arm. The first protrusion parts protrude from the second surface and are disposed around the driven hole, and at least one of the first protrusion parts has a first locked hole. The locking part is detachably secured to the first through hole and the first locked hole such that the first chainring and the second chainring are jointly secured to each other via the locking part.