In order to achieve the ideal “reduction ratio” between the rpm of the engine and the rpm of the rear wheel, reduction ratios are employed at three points: (1) between the engine and the clutch, (2) in the transmission, and (3) at the sprockets at either end of the chain. When starting up a large reduction ratio is necessary, while a small reduction ratio is needed to run at high speeds. The 6-speed transmission of the YZF-R15 is designed to provide the right reduction ratios for sprite, agile running performance plus good fuel economy.