Nitro bikes are motorcycles that have been used for drag racing since the 1980s. Also known as Pro-Stock and Top Fuel motorcycles, they use nitromethane as a fuel rather than gasoline. They are second only to Top Fuel race cars in speed, and can reach 230 miles per hour (370.15 kph) in less than six seconds.
Nitromethane, or nitro, is produced especially for drag racing, but is also used for fueling rockets and model airplanes. It is a result of a chemical reaction between propane and nitric acid. The high oxygen content of nitromethane enables it to burn with less atmospheric oxygen than gasoline. Drag racers must be careful, however, as nitromethane is highly explosive. Engine explosions have been known to occur if a nitro bike is not handled properly.
The body of a nitro bike is built to withstand extreme speed. The front tire looks normal for a motorcycle. The rear tire, however, is an oversized square tire framed by a wheelie bar that extends 130 inches (330.2 cm) behind it. The front tire pops up off the ground when the bike starts to accelerate. Wheelie bars prevent the bike from flipping over when the front of the bike is in the air.
With a 1,000 horsepower engine, a nitro bike can hit 100 miles per hour (160.93 kph) in 1 second. Riders experience five Gs of force as the bike accelerates. A nitro bike can complete a 1/4 mile (402 meter) race track in six seconds.
When mounted on the bike, a rider looks like he is lying face down with legs splayed out and back. Since the nitro bike is built for racing in a straight line only, steering is done with the body to move the bike to the left or right. It requires training and experience to drive one of these bikes. The gravitational forces alone can cause vomiting and loss of consciousness.
Before the start of the race, a rider "burns out" his rear tire. To do a burn out, he spins his back tire in a puddle of water to heat the rubber to increase the tire's traction on the track. The rider then lines up, or stages, his nitro bike at the starting line. A starting device known as a Christmas tree light sits between the lanes and counts down to green. When the green light is lit, the riders accelerate, and the first one across the finish line is the winner.
Time is the only real indicator of performance in a drag race, but race tracks often keep records of reaction times, speed, and elapsed time. The reaction time is the time it takes a rider to accelerate when the light turns green. It is entirely possible for a nitro bike rider to have the fastest speed and elapsed time, but lose the race because he had a slow reaction time.