It shifted from the STD mission of the wide ratio to the cross ratio with little decline in rotation. It subdivided the ratio between each gear by making it 4-gear to 5-gear. It will enable to smooth riding. It cross ratio the 4-gear of the STD mission which has a large decline in rotation. It improves the connection of the gears and can effectively use the power band. In addition, it adopts nickel chromoly steel which is strong and durable excellent as a material.