Suspensions are key to effective bike control, performance and comfort on your mountain bike. However, one is often amazed at how many of us have not learned how to tune our suspensions to optimize performance and riding comfort.

Every suspension fork and rear-suspension system comes with instructions for tuning it for best performance. Read this material or talk to the staff at the local bike shop where you bought the bike and learn what those knobs are for in setting adjustments. Then use them.

Too many riders don't maximize their bikes' shock-absorbing ability by adjusting the suspensions for their weight and riding surface. The adjustments aren't difficult.

Set the preload so your system is responsive to small hits and occasionally bottoms out on the biggest ones. This will give you the full movement in typical terrain. Spring rate determines how much of the suspension's range of motion is used (by determining the amount of force required to compress the suspension). Depending on your suspension, spring rate is adjustable via air, elastomers, or a metal coil. The first is easy to adjust with a pump, while the other two require part changes.

Damping is another factor in suspension setup. There are two types in each suspension — compression and rebound — which are usually controlled by a plunger running through oil. Damping lets you tune the shock's reaction to a bump. You want the shock to return to its original position and be prepared for the next hit, but not recoil so fast that it causes the bike to bounce.

It's best to experiment. Generally, if you want a more stiffer suspension action you need to run a little higher spring rate or higher preload. This will reduce pedaling-induced suspension movement on the flatter, smoother sections of a trail. But it may also reduce the shock's ability to soak up little bumps. Keep adjusting and testing to find the efficiency-to-smooth ride ratio that suits your terrain and riding style.

Once you have the hang of your system, you'll feel confident to customize the settings for the terrain of a particular ride. For instance, if I'm riding on a smooth course, crank up the preload and increase the compression and damping. You want the suspension to be less active.

If it's a rough course, back off the preload and lighten the damping. On most suspension systems, these adjustments are easy to make using external knobs, if you know the direction and to turn them. Follow the directions in the owner's manual.

Eventually, your suspension system will begin to respond differently for various reasons, such as loss of air pressure or the coming contaminated with dust. Wear occurs to springs, elastomers, and pivots — just think of all the abuse your bike goes through.

The key to reliable and predictable performance is to service your suspension according to the manufacturer's directions. Many suspension fork manufacturers include details on how to tune their forks on their Web sites.