Abstract: The present sprocket wheel invention enhances the efficiency of the sprockets made of two materials, e.g., a lighter material at central portion of the sprocket and a hard material at peripheral portion of the sprocket comprising teeth, by drilling half holes on the outer edge of the central portion and half holes on the inner edge of the peripheral portion of the sprocket. In the preferred embodiment, half of the thickness of the sprocket is the entire hole on the peripheral portion of the sprocket with harder materials, and the other half of the thickness of the sprocket is designed to have said half holes for rivets to attach the central portion and the peripheral portion of the sprocket.