Shock / rear suspension

How it works

The rear shock links the swingarm to the frame, either directly or through a linkage that makes the suspension progressive. Like the fork, it combines a spring, which carries the load, and a hydraulic damper, which controls how fast the suspension moves. Some bikes have twin shocks, others a monoshock. Spring preload is adjusted to set ride height for the load (solo, passenger, luggage); rebound and sometimes compression adjustment are often available. With mileage, the shock's oil degrades and damping fades: the rear pumps, bounces after a bump and the bike feels vague in corners. Oil on the shock body means it is finished. Linkage bushes, rod ends and bearings also wear and create play or clunks. A shock is rebuilt by a specialist or replaced.

Maintenance tips

• ✓Adjust preload to the load: more with a passenger or luggage, following the manual's settings.
• ✓Test damping by pushing down firmly on the seat: the rear should come back up once, without bouncing.
• ✓Inspect the shock body: an oil trace means a failed seal.
• ✓Grease the linkage and swingarm bearings at the specified interval, especially if you ride in the rain.
• ✓Rebuilding a shock (often nitrogen-charged) is specialist work.