Final Drive
Power transfer from the gearbox to the rear wheel is accomplished by different methods.
Chain drive uses sprockets and a roller chain, which requires both lubrication and adjustment for elongation (stretch) that occurs through wear. The lubricant is subject to being thrown off the fast-moving chain and results in grime and dirt build up. Chains do deteriorate, and excessive wear on the front and rear sprockets can be dangerous. In a chain drive the power is transmitted into the real wheel via a cush drive. Conventional roller chain drives suffer the potential for vibration, as the effective radius of action in a chain and sprocket combination constantly changes during revolution. If a drive sprocket rotates at constant RPM, then the chain (and the driven sprocket) must accelerate and decelerate constantly. Most chain-driven motorcycles are fitted with a rubber bushed rear wheel hub to eliminate this vibration issue. Virtually all high-performance racing motorcycles use chain drive.
A belt drive is still subject to stretch but operates very quietly, cleanly, and efficiently. However, belt drives are limited in the amount of power they can transmit. A toothed belt is frequently used.
A shaft drive is usually completely enclosed; the visual cue is a tube extending from the rear of the transmission to a bell housing on the rear wheel. Inside the bell housing a bevelled gear on the shaft mates with another on the wheel mount. This arrangement is superior in terms of noise and cleanliness and is virtually maintenance free, with the exception of occasional fluid changes. However, the additional gearsets are a source of power loss and added weight. A shaft-equipped motorcycle may also be susceptible to shaft effect.
Read more about this topic: Motorcycle Components
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