Suspension Basics

(work in progress)

Suspension Basics

This article will give you some of the basic knowledge required to understand what is going on underneath you.


  • Clickers – generic term for any damping adjustments. These may include adjustments that actually click, like low speed compression and rebound on most forks, and adjustments that don’t actually click, like most shock high speed compression adjustments.
  • Compression – the movement of suspension from a more extended position to a less extended position
  • Rebound – the movement of suspension from a less extended position to a more extended position
  • Top/Bottom Out – reaching the mechanical limits of suspension travel in rebound or in compression, respectively
  • Shims and Shim Stacks – small, specialized discs in most modern suspension dampers which create flow restrictions via deflection
  • Wheel Rate – relative ratio of the motion of the wheel vs. the spring or damper. Fork springs move the same as the front wheel, giving you a motion ratio of 1. Shocks often move around 1/3 the travel of the rear wheel, which would be a motion ratio of 0.33
  • Linkage – rocker and pull rod that allows the motion ratio of the shock to change based on where the wheel is in its stroke, instead of being a linear value as in a PDS or direct-acting suspension.
  • PDS – progressive damping system, specifically referring to the WP shock with a secondary piston engaging only in the last part of the shock stroke. Colloquially, people tend to use this referring to any shock that mounts directly to the swing arm even if it doesn’t have the dual-piston PDS setup. This is a misnomer, but a common one.
  • Viscosity – the resistance of the oil in the dampers to flow. Higher viscosity has more flow resistance.
  • Low and High Speed Damping – generic terms referring to the rate of movement of the suspension. There’s no standard boundary for these values, but consider low speed as slow motion, like jumping on the pegs of the bike or compressing into a jump face. High speed would be sharper hits like slamming into roots and rocks. Low and high speed damping are NOT related to the speed you are traveling on the bike.

Key Components to Tune Suspension

  • Springs resist static forces on the bike. Rated in force/compression distance, purely based on how far they are compressed.
  • Dampers (forks and shock) resist dynamic forces on the bike. They, generally speaking, do not change with how far the suspension is compressed. Instead, they change with how quickly the suspension is moving.
  • Tires, specifically tire pressure. Tires are responsible for a lot of the small bump characteristics of the bike, and have their own effective damping and spring rate. This is why tubes feel so different from mousses, even though you are not changing your suspension.
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