Shock absorber (damper)

A shock absorber, often just called a shock, is the rear suspension unit of a motorcycle. Strictly speaking the spring absorbs the bump, while the damper controls how fast the spring compresses and extends by forcing oil through small valves and shim stacks. That turns motion into heat and stops the bike bouncing.

Bikes have either one shock (monoshock) working through a linkage or directly on the swingarm, or twin shocks on each side. Better shocks offer adjustable preload, rebound and compression damping, and many use a gas reservoir to prevent oil foaming.

Signs of a worn shock are a bouncy or wallowing ride, oil on the shaft and poor grip on bumps. Shocks need servicing (oil and seals) at intervals, not only replacement.