Rear shocks serve two basic functions: the spring stiffness supports the weight of the rear of the motorcycle, and it controls the up and down vibrations of the suspension by providing damping. Damping is controlled friction and its job is to absorb energy during suspension movement, without a damper the spring would continue to bounce after each impact.

   Dampers work by dry friction, but their piston motion is unstable. Modern dampers work linearly because they consist of an oil-filled cylinder and a movable piston connected to the suspension. Suspension motion drives the piston, which pumps oil back and forth through a restricted hole. This converts the energy of suspension motion into a rapid flow of damping fluid to dissipate heat. The temperature brought by the compression movement in the middle and rear is the energy consumed by the suspension movement.