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SUSPENSION: Rear Suspension (Introduction)



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The rear suspension absorbs the shock caused by a bump in the ground or rough terrain. A shock absorber must be kept clean and lubricated, and the bushings and frame mounts checked regularly for damage and wear.

 

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How rear suspension works

How rear suspension works

The shock absorber of the rear suspension mirrors the specifications of the front fork in order to increase the rider’s control of the bike. The rear triangle of the frame, which connects the rear wheel to the shock absorber, can move independently of the rest of the frame on bikes that are fitted with rear suspension.

Shock absorbers, or shocks, as they are also known, consist of a spring medium, either a coil or trapped air, and a shaft. The shaft is usually connected to a damping mechanism, which contains oil and controls the speed of the shock absorber’s action.

  • Adjusting the shock: The shock absorber of the rear suspension can be adjusted to suit different kinds of terrain and gradients.
  • Rear shock: Absorbs the force of a bump.
  • Rear triangle: Transmits the force of a bump to the rear shock.
  • Rear wheel: Moves up and down in response to bumps.

Compression of the Shock Absorber

When the back wheel hits a bump on the road or trail, the rear triangle moves up on its pivots, compressing the spring, which absorbs the shock.

As the spring pushes back on the rear triangle of the frame, the shock rebounds, pushing the rear wheel back ready for the next bump.

(left) When riding over smooth ground the rear shock absorber is in a neutral position.

(right) When riding over rough ground the rear shock is in a compressed position to absorb bumps.

 

How an AIR/OIL SHOCK ABSORBER works

In an air/oil shock absorber, the spring mechanism is compressed air that is sealed inside an air sleeve. The damping mechanism in the shock body contains oil. When the bike hits a bump, the shock body travels up inside the air sleeve and compresses the trapped air. Once this air spring has absorbed the energy of the bump, the shock absorber begins to rebound and return to its original position. The shaft, which runs from the top of the air sleeve into the shock body, is connected to the damping device. Oil flowing through holes in the device slows the action of the shock absorber in compression and rebound as the shock body travels up and down.

  • Bushing: Attaches shock to frame
  • Air valve: Controls air pressure in the sleeve
  • Rebound adjuster: Changes speed of rebound
  • Shaft: Runs into shock body
  • Air sleeve: Contains compressed air
  • Shock body: Contains the damping device
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Brake pad: Slows down the wheel When riding over smooth ground the rear shock absorber is in a neutral position