5/ How to adjust the compression of your suspension
After adjusting the sag and the rebound (release), you can now adjust the compression of your fork. This adjustment is a bit more complicated than the two previous ones. Remember: adjusting the compression will change the speed at which the suspension descends (compresses). It is adjusted using a dial (typically blue in colour with the marking CHARGER or COMPRESSION) on the right side of the T of the fork.
Entry-level suspensions typically don't come with a way to adjust the compression; others only have two positions (open, closed), others have a single compression adjustment that can be set to several positions, and lastly, high-end MTB enduro/gravity forks have two compression adjustment mechanisms.
1. Locking the suspension
On some forks and shocks, the compression dial has only two positions: open and closed. When the dial is in the open position, the suspension works normally. When in the closed position, the suspension is much more rigid, nearly "fully-locked", which yields better performance on smoother terrain, uphill climbs, or riding on paved roads.
To lock the suspension simply turn the dial which is located either on the handlebar or on the suspension itself, depending on the model.
2. Low-speed compression adjustment
This adjustment is only on suspensions that have one or two compression adjustments made using a dial with several positions. When the fork or shocks only have a single compression adjustment, this adjustment regulates the low-speed compression.
What is low-speed compression?
It concerns compressing the suspension at the start of a ride or when riding over small bumps, when braking, or when pedalling force is applied by the rider.
A low speed compression setting that is too open can result in a loss of traction when applying force, braking, or on a raised turn or banked curve. Conversely, a low speed compression setting that is too closed will make your suspensions too firm and you will feel the jitter from small bumps much more in your arms.
3. High-speed compression adjustment
This adjustment is only found on suspensions that have two compression adjustment mechanisms. The central ring is for the low-speed compression, while the outer ring is for the high-speed compression.
What is high-speed compression?
It's the compression of the suspension at the end of the course, or over large bumps such as very uneven terrain, or when landing jumps.
If during steep descents over very uneven ground you feel you don't have enough manoeuvrability or that your bike is shaking too much, your high-speed compression setting is too closed. Conversely, if you feel that the fork or shock goes in too far on impact it's because your high-speed compression is too open.