DAMPING CIRCUITS EXPLAINED
There is a fundamental difference between compression and rebound damping. Compression damping has to deal with a much wider range of velocities, generated by bumps of difference sizes and shapes. Rebound damping on the other hand primarily has to control the energy of the compressed spring and therefore adjustments are easier to perform and control.
Compression velocity - and therefore damping - is affected by the shape and by the size of bumps, as well as the speed at which you hit them. Some bumps like square edged kickers and jumps landings, cause the suspension to move rapidly upward while others produce slower movement, like big waves in the sand. This is the reason why high and low speed compression damping exisits. The terms refer not to the forward speed of the bike but rather the velocity of the suspension movement. Low speed adjustment refers to low shaft speeds and high speed to hight shaft speeds. Examples of high shaft speed obstacles are, square edge bumps, slap down landings, lipped out jump faces. Examples of low shaft speed obstacles are rolling bumps/whoops, steep jump faces and accecleration.
Changes in rebound damping affect traction, the feeling of control and ride plushness. With less rebound damping (open screw), the wheel moves quickly and the ride quality is plush, at the extreme end to the point of being loose. As rebound is increased, the feeling of plushness drops off until, at the extreme end, the ride feels harsh.
The easiest way to explain clicker adjustment is a shim stack bypass or bleed hole controlled by a moving tappered needle. As you wind the clicker in it closes the bypass and forces more oil across the shim stack creating stronger damping forces and vice versa when winding the clicker out.
The main principles are identical in forks and shock alike.
When adjusting clickers it is best to always start in the middle of the adjustment and always count from completly closed. The closer you are to 0 clicks (closed) the more coarse the adjustment is. When you are tuning always start with the rebound adjustment first as it effects both rebound and compression circuits.