What is Dirt Biking?

Motocross is the most dangerous sport in the world, but racers from age three to fifty-three don't think of the danger. They're caught up in the thrill of racing. "I like to go fast and feel like I'm flying," Josh said.

All races begin at the starting gate. On the smaller tracks, the gate may be a piece of rope or chain that is dropped and the racers speed onto the track. The larger tracks have high-tech electronic devices. The one in this photo is similar to the one described in Dirt Bike Rider. Each rider has his own individual gate with a trip switch that lets the gate fall down, and racers ride over the gate.

Proper equipment is expected around the motocross track. No one enters the track without a helmet, goggles, jersey, pants, boots, gloves and a chest protector. Most young riders also wear neck protectors.

Full-face helmets should fit snugly, with thick lining that protects the head, and a protective outer shell of fiberglas or another rock-hard synthetic hybrid that will not shatter in a crash. Helmets must be lightweight, around three pounds. Most racers place decorative graphics on their helmets and ask the pros to sign them.

Goggles need wide elastic straps for a snug fit to keep dust and dirt out of the rider's eyes. Scratch resistant lenses in an eye-protecting color are best.

Jerseys made of nylon or cotton look hot because they have long sleeves and the fabric does not breathe, but they protect the rider's upper body under the chest protector.

Pants are usually a good quality nylon and leather combination. Velcro holds vinyl hip protectors in place under the pants.

One-piece thigh and knee protectors are made of high impact vinyl. They protect the top of the leg and a hinge allows them to bend at the knee. The rider straps them onto his legs, under his pants.

Boots made of thick leather protect the entire foot and shin.

Gloves are made of nylon with leather palms for a good grip.

Chest Protectors help protect the chest and back from flying dirt and rocks, and provide some protection in case of a crash.

All of the equipment looks like it's too hot for a warm summer day, but the wind on the track helps keep the rider cool. The newer helmets have ventilation built in, and the rider knows s/he will be wearing the protective gear only for the race. Riders usually change into street clothes right after the race.

Do you know the difference between a dirt bike and a road bike?

Road bikes are heavier, faster and more powerful than dirt bikes. They have smooth tires for the paved roads where they are ridden.

Dirt bikes are also called off-road bikes, and they are ridden through rough terrain, with dirt, mud and rocks. They have knobby tires, lightweight frames, long-travel suspension, and special engines placed high enough that they do not get filled with mud and dirt.

The knobby tires give more traction than smooth tires, especially in deep sand and slippery conditions. These tires make for a bumpy ride on paved roads, though, and smooth tires are available for the dirt biker who needs to ride on streets and highways.

The long travel suspension includes a fork and shock absorbers that help soften the ride, but most dirt bikers agree that their ride is still rougher than a road bike's.

The engine and exhaust pipe are placed high on the chassis to clear bumps, rocks and other obstacles. A steel casing is installed below the engine to protect it and the other parts. When a rider hits this casing on the top of a jump, the bike goes out of control and crashes. It's called "casing the jump."

The engines are either two-stroke or four-stroke. The spark plug ignites the mixture of air and gasoline in the engine, and the explosion moves a piston up and down inside the cylinder. It's called a power stroke. The power stroke becomes a circular motion in the crankshaft that moves through the gearbox by way of the clutch and drive chain. A two-stroke engine produces a power stroke for every turn of the crankshaft, but a four-stroke engine operates on every other stroke. The other strokes let out the exhaust.

Racers who forget safety rules are kicked out of the race. Other racers yell at those who ride dangerously. "I have to concentrate all the time when I'm racing," Josh said. "I have to keep my head in the race, and know what the riders around me are doing. I can't switch lines (lanes) in front of someone or pull a stupid trick that would endanger another rider." Parents start enforcing safe riding rules as soon as their little racer straps on his first helmet. They keep saying the rules over and over.

One important safety consideration is the dirt bike itself. Most parents help the rider choose a bike that lets the rider's feet touch the ground, with legs slightly bent. In Dirt Bike Rider, Josh rides a bike that's too large for him, and it creates problems.

When the rider's dirt bike leaves the ground for a few seconds, it's called "getting air." Beginners get only one or two feet of air, but professional riders climb several feet into the air and come down safely. (Usually) The riding you see on TV takes hours and hours of practice.

You'll read more about the Moon Jump in Dirt Bike Rider book coming soon.