Bike Repair – Fork set-up

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This insight into the black art of tuning long-travel suspension will help you squeeze every last ounce of performance from your fork.

Checking fork sag

Move the O-ring around your stanchion down so it’s sitting on the dust seal. If you have no O-ring, loosely fit a zip-tie to the fork. Mount your bike fully kitted up and get into an aggressive riding position. You should be using around 25-30% of your fork’s total travel as sag. If you’re using too much or too little of your fork’s travel, a change of coil spring is needed.

Adjusting preload

The preload adjuster on the top of the left leg compresses the spring and changes the fork’s feel. Wind it clockwise to make the spring feel harder or anti-clockwise to soften it up. If you can’t sort out your sag issues with this, you’ll need to change your coil spring.

Changing coil spring

To change your coil spring, remove the left leg’s top cap keeping any spacers underneath it in order, before pulling out the coil spring. Most are color coded to indicate their spring weight, which helps identify you’re making the right change. Pop the new spring in, refit any spacers and torque the top cap to the manufacturer’s recommended torque setting.

Adjusting air spring

Remove the air adjust cap from the top of the left-hand leg. Screw the shock pump onto the valve until the pressure registers on the pump, then screw on another quarter turn. Note the air pressure, inflate or deflate, and note the pressure again. Remove the shock pump and measure your sag. Repeat until you’re satisfied with your sag measurement.

Rebound 1

Locate the rebound adjuster on your fork, usually red in color. On both Fox and RockShox forks it’s located at the bottom of the right-hand leg. Turning the adjuster clockwise will increase rebound damping, making your fork return more slowly. Turning the adjuster anti-clockwise will decrease rebound damping, speeding up the return phase.

Rebound 2

Push down on the fork with all of your weight and let it spring back. If you can lift the front wheel high off the floor before the fork extends it has too much rebound and is too slow. If you feel the fork trying to push you away and you can’t lift the wheel off the floor, it’s too fast. Experiment with settings on the trail to find what you prefer.

Compression

Locate your fork’s compression adjuster/s. They’re normally found on the top of the right-hand leg. Compression damping determines how fast the fork can compress when hitting an obstacle or bump. More compression damping and the fork will be less sensitive to small bumps, less and it will be more prone to falling through its travel and feel mushy.

Low-speed compression

If you have a separate low-speed compression adjuster, it affects how the fork behaves at lower shaft speeds, like when pedalling or compressions into berms. Too much low-speed compression damping and the front wheel will tend to deflect off objects easily. Too little and the suspension will dive, using more travel than it needs to.

High-speed compression

High-speed compression damping affects higher shaft speeds such as hard landings, square-edge hits and G-outs. Too much high-speed compression damping and the fork will give a rough ride and feel too hard. Too little and the fork will dive through the travel easily and feel out of control in rough sections.

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