Dirt jumping

Dirt jumping is one of the names given to the practice of riding bikes over jumps made of dirt or soil and becoming airborne.

Several types of bikes can be used in dirt jumping.

A mountain bike built for dirt jumping tends to have a smaller frame than what is used for other disciplines. Running singlespeed with one brake is very common. using single or dual disc brakes has replaced the use of only one rear V-brake. In general, a mountain bike dedicated to dirt jumping will have 24- or 26-inch wheels, a gear ratio of approximately 60 gear inches (~36:15 on a 24-inch rear wheel or ~36:16 on a 26-inch rear wheel) and rigid or 80-100mm travel forks. An 'all-round' bike used for dirt jumping will more likely have 26-inch wheels, a 25-36 tooth chainring with a wide-ratio cassette and a short- to mid-travel fork. Mountain bike dirt jumpers are usually split on the basis of wheel size because the wheel size dictates the shape of the takeoff to an extent.

A 20-inch BMX bike for dirt generally has a 48-spoke rear rim and a 36-spoke front to prevent rim collapse in the case of casing a jump. The frame is a little bit longer to aid in stability and to spread the load of heavy lands. Most of these "micro geared" bikes run 85 to 100 psi tires, and tires are usually threaded and made with kevlar bead to prevent pressure flats and tears.

Dirt Jumping evolved alongside BMX racing and is similar to BMX or Mountain bike racing in that the rider jumps off of mounds of dirt. It differs in that the jumps are usually much larger and designed to lift the rider higher into the air. Additionally, the goal is not to complete the course with the fastest time, but rather to perform the best tricks with the best style.

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