Inspection. 
Always check the brakes and other components for damage before you ride. Take along repair equipment and learn how to make basic repairs in the field, such as fixing a flat tire. After a ride, clean debris such as twigs, grass and small pebbles and rocks from the chain, spokes and shifting mechanism (derailleur). Also clean dirt and debris from the brakes.

Cadence. 
Use your gears to keep a cadence — the rhythm of your pedaling — between 80 and 100 revolutions per minute (rpm). "Certainly this will vary depending on the steep climbs and descents that you encounter, but generally a cadence of 80 to 100 rpm is less stressful to the knee because it doesn't involve a lot of grinding torque," says Dr. Laskowski. "When you pedal in the 40-, 50- or even 60-rpm range, it produces a fair amount of compressive force on the knee, especially under the kneecap." A cycle computer with a cadence meter is a helpful device to track your pace and training progress.

Shifting. 
Lower gears make it easier to pedal, and higher gears make it harder. Learn how the gear combinations between the chain ring, at the pedals, and the freewheel, at the rear wheel, make it easier or harder for you to pedal. Part of the fun of mountain biking is anticipating changes in terrain and shifting accordingly. "It's a good trick to shift to a lower gear ratio as you end your descent of a hill so that you don't have to start the uphill in too high a gear, which can stress your knees," Dr. Laskowski says. "The same concept works as you approach a descent. You don't have to shift immediately toward your highest gear. You can notch it up gradually as your cadence permits."

Descents. 
On a steep descent, move backward on the seat and put your weight over the back wheel to improve your balance. You can even move off the seat entirely when going down extremely steep terrain, but be careful.

Climbs. 
It's OK to get out of the seat and rock the bike back and forth a little as you pedal up a hill. However, too much rocking — or pedaling in too high a gear — wastes energy and is hard on your knees.

Braking. 
The front brake usually has about twice as much stopping power as the rear brake. Applying the front brake suddenly during a steep descent or even on the flats can send you over the handlebars. Instead, start with the back brake and gradually bring in the front brake or use both brakes gradually and simultaneously.

Cornering. 
Don't begin braking while turning. Brake gradually to a safe speed before you go into the corner, then begin to accelerate as you come out of the corner.

Skidding. 
Applying the back brake hard can put you into a skid. This robs you of control of your bike and may cause damage to the trail.

Obstacles. 
Pick a path and focus on it. Learn the skill of lofting — pulling up on your handlebars — and shifting your weight back to get your front wheel to hop over obstacles such as rocks, logs and bumps.

Common sense. 
Practice off-road riding skills on easier terrain before you rattle up and down the more challenging stuff. Always ride in control, and walk your bike through terrain that looks risky. Yield to and be respectful of other trail users. Be careful not to spook animals, especially horses, which can kick you or throw their rider.

Wilderness safety. 
The rules for hikers apply. It's easy to get lost when you're having fun on a bike. Tell others where you're going. Take a map, compass or Global Positioning System (GPS), a first-aid kit, plenty of water, and appropriate clothing.