Lubricate wheel bearing regularly; if bearings are missing, install new bearings on all the wheels.

The most important parts of skateboards are the wheels. To keep them moving at top speed, service the bearings whenever the wheels start to bind. Here's what you'll need to maintain your skateboard's wheels.

Tools: two small adjustable wrenches, pliers, screwdriver.

Materials: household oil, bicycle grease, replacement ball bearings, rags.

Time: about 15 minutes to 1/2 hour.

When skateboard wheels drag or bind, the problem is usually in the wheel bearings. Spin the wheel that's binding and look at the space between the axle and the edge of the wheel, behind the wheel nut. If you don't see small steel bearings in this space, the wheel bearings are sealed; have them adjusted or replaced by the skateboard dealer. If you see small ball bearings around the wheel, the wheel is constructed with open bearings, eight balls on each side of each wheel. You can lubricate and adjust these bearings yourself.

To service ball-type bearings, lubricate them periodically. Spin the wheel that's binding. If the bearings are noisy, they should be lubricated with oil. Apply household oil sparingly to each side of each wheel, every other time you skate. Don't over-oil; excess oil attracts dirt.

If the bearings are quiet, they should be lubricated with grease. With a small adjustable wrench, remove the wheel nut from the axle. Unscrew the cone over the bearings and remove it. Take the wheel off the axle.

The bearings are held into the bearing races by bicycle grease. To lubricate them, apply a coat of bicycle grease to the balls and the race; remove excess grease from the wheel with a rag. Lubricate the bearings and the race on each side of the wheel, and then replace the wheel on the axle. Replace the cone over the bearings and hand-tighten it; then replace the wheel nut.

After greasing the bearings, adjust the cone and the wheel nut to the proper tightness. Hold the cone with a small adjustable wrench to keep it from turning. With another wrench, tighten the wheel nut. Tighten the nut only until the wheel spins freely but doesn't wobble; the wheel should not bind. It's better to leave the wheel a little loose than to overtighten it.

Each wheel should have 16 ball bearings, eight on each side of the wheel. If bearings are missing, replace the complete set of bearings with new bearings; buy the replacements at a skateboard shop. Even if only a few bearings are missing, buy a complete set of new bearings for all wheels; don't mix new and worn balls.

To replace the ball bearings, remove the wheel nut from the axle; unscrew the cone and remove it. Take the wheel off the axle. On each side of the wheel, remove the remaining old bearings from the bearing race, and clean old grease from the race with a rag. Coat the race with a thin layer of bicycle grease and set eight steel ball bearings into the race; the grease will hold the bearings in place.

After replacing the bearings on both sides of the wheel, replace the wheel on the axle. Replace the cone and the wheel nut, and adjust the wheel as above so that it spins freely.

Keep these tips handy -- they'll help you spend more time at the skate park and less at the repair shop.

For tips on caring for and repairing other types of sports equipment, try the following links: