It's also important; if your suspension is set up properly it will extend the life of your fork and shock, it will give you better control of your bike, plus it will give you a better ride.
For some riders suspension set up is a complete mystery, you bought a bike - new, used or online - the suspension was likely already set up, (for the previous owner or from the factory for an "average" 150lb riding weight) and you never give it another thought. But just like your tires, the fork and shock will eventually lose air. Get yourself a shock pump, weigh yourself in your riding gear, and check out the videos below. Better yet - stop by the shop and we'll help you out.
Find your baseline: Look up your bike's recommended sag percentage, typically 15-25% for the front fork and 25-30% for the rear shock.
Reset the O-ring: Push the O-rings on your fork stanchions and shock shaft all the way to the top.
Pump to the correct pressure: Use a shock pump to add air until you reach a pressure roughly equal to your body weight in pounds as a starting point.
Bounce and compress: With your riding gear on, get on the bike and do some gentle bounces. Then, sit on the bike and let it compress to find the sag, measuring the distance the O-ring has moved down.
Adjust air pressure: Add or remove air using the shock pump to get the correct sag measurement.
Use preload for fine-tuning: If you're slightly off, use the preload collar to make small adjustments. Turn the collar clockwise to firm up the spring or counterclockwise to soften it. Do not turn more than two full turns.
Locate the rebound adjuster: This is usually a red knob, often found at the bottom of the fork leg and the shock eyelet.
Set the base position: Turn the knob fully clockwise to "closed" (slow) and then back it out to a recommended setting from the Fox manual or the video you are watching. For example, a starting point might be 8 clicks out from closed.
Check the return speed: Push down on the handlebars and let go. The fork should return to its original position quickly, but not so fast that the wheel leaves the ground.
Slow if too fast: If the tire is leaving the ground or the bike feels bouncy, turn the rebound knob clockwise (slower) a few clicks at a time until it feels right.
Speed up if too slow: If the suspension feels slow to return (known as "packing down"), turn the rebound knob counter-clockwise (faster).
Adjust high-speed compression: This affects large, fast impacts like those from landing jumps. It's often a smaller knob on top of the fork. A good starting point is 5 clicks out from fully closed.
Adjust low-speed compression: This affects smaller, slower compressions from body movements and pedaling. It's often a blue knob at the bottom of the fork. A starting point might be 10 clicks out from fully closed.
Make adjustments on the trail: It's best to fine-tune both compression and rebound on the trail. Keep notes of your settings and adjust them in small increments based on how the bike feels.