![ShaftDrivePower](https://upload.wikimedia.org/wikipedia/commons/7/71/ShaftDrivePower.png)
The shaft effect, also known as elevator effect or shaft jacking, is a phenomenon occurring in shaft-drive
motorcycle
A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...
s. This effect occurs because the acceleration being applied to the rear wheel creates a reactive force on the drive shaft. This in turn lifts the rider and the body of the bike, exacerbating the natural "tucking under" of the rear wheel. Under acceleration Newton's third law says trying to turn the wheel forward exerts a reactionary force against the drive mechanism. In the case of a belt, this makes the top part of the belt tighten and the whole bike "shrug" down just a bit. This is typically obscured because acceleration causes the rear wheel to "tuck under." A shaft-drive, on the other hand has a rigid connection to the hub so this reactionary force turns the shaft backwards about the rear wheel and the middle of the bike "tightens" and lifts the rider up. This effect is one of the most notable differences between riding a shaft-driven motorcycle and a typical motorcycle. The effect is most pronounced on older models of motorcycle as most modern shaft-driven bikes use one or two
Paralevers to limit the rotation of the rear hub relative to the bike frame.
See also
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Bicycle and motorcycle dynamics
Bicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics falls under a branch of physics known as classical mechanics. Bike motions of interest ...
References
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HPN Motorradtechnik GmbHParalever, Suspension and Driveshaft factorsMotorcycle Road Test: Suzuki Intruder 1400o
motorcyclecruiser.com
{{motorcycle-stub
Motorcycle transmissions
Motorcycle dynamics