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Dirt Jumping is the practice of riding bikes over shaped mounds of dirt or soil. Basically, the idea is to ride over the “take off,” become airborne momentarily, and land on the “landing.” It formed with BMX racing, but tends to use jumps that are much larger and designed to project the rider higher into the air for a prolonged period of time. It is mostly is done for fun, rather than for competition, and is known as a ‘freesport.’ Recently, contests for have started to organize, especially in the UK. However, it is still a very underground sport, and that is one aspect some people love about it. It can be performed on almost anything with wheels, but it usually is done with BMX or Mountain bikes.
Many people have different styles of dirt jumping and prefer to use different types of bikes for dirt jumping. The two most commonly used bikes are BMX and Mountain bikes.
A BMX bike that has been built for dirt jumping will have a longer top tube and be more reinforced than other BMXs. A BMX bike will rarely have pegs, and will tend to only run on the rear brake. The tires used on BMX bikes are usually semi-slicks, and the saddles are generally more padded for landing comfort. A BMX dirt jumping bike usually has a gear ratio in the region of 44:16.
A Mountain Bike that is built for dirt jumping usually has a smaller frame than other mountain bikes. It will generally only use one speed and only the rear brake. The forks on mountain bikes will either be rigid or short travel (up to 100mm). A bike dedicated to dirt jumping will generally use 24” wheels, and have a gear ratio of 1:2 (32:16, 36:18, and 24:12). A mountain bike intended for trail riding and dirt jumping will generally use 26” wheels. It will also use a 30-36t chain ring with a wide-ratio cassette and a short to mid-travel fork.