Speed wobble or shimmy is the spontaneous oscillation of the front wheel(s) of a vehicle, at a set speed or speed range. The oscillations are due to the latent resonant frequency of the vehicle and are a complex phenomeon which are not fully understood. It can occur with motorcycles, skateboards, bicycles or in theory any vehicle with a single steering pivot point; this does not include automobiles. While usually easily remedied by adjusting speed or changing position on vehicle, speed wobbles can be fatal, especially at high speeds.
In 2002 Harley-Davidson was sued in a class action suit for injuries associated with high speed wobbles, also known as "tank slappers" because of the tendancy of handle bars to move towards the tank.
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