A belt-drive is still subject to stretch but operates very quietly, cleanly, and efficiently. A toothed belt is frequently used. However, they are not as durable when subjected to high horsepower as a chain. You can not alter the length and change final drive ratios as easily as chains. They also can not wrap as closely around chains. And require larger pulleys compared to chain sprockets to get an effective final drive ratio. Replacing a drive belt typically requires removal of the swingarm, since belts cannot be split the way a chain with a master link can.