Working of Telescopic Hydraulic Fork:  When a road shock exerts on to the suspension system it is transmitted to the spring instead of motorcycle frame and the spring starts to oscillate. The springs are supported on the piston which is not allowed to move much by the hydraulic fluid.

Figure: Front Suspension Fork

Because of road shock initially piston moves upward and compresses the spring. The damping oil from chamber A transfers to chamber B through a bigger hole as shown in Figure. During the reverse movement of the piston the damping oil transfers from chamber B to chamber A but this time through a smaller hole. The transfer of oil offers resistance to spring oscillations hence some energy is lost to overcome this resistance. As a result the spring oscillation amplitude (movement) will be lower than before. In this way finally the oscillations of spring will be stopped.