Dirt Jump

Dirt jumping is one of the names given to the practice of riding bikes over cement type jumps of dirt or soil and becoming airborne. The idea is that after riding over the 'take off' the rider willbecome momentarily airborne, and aim to land on the 'landing'.
Dirt jumping can be done on almost anything with wheels, but it is usually executed on a dirt jump bike.
* BMX bike built for dirtjumping tends to have a longer top tube than a street BMX bike, and may well be more reinforced. They will rarely have pegs fitted (unless they are also used for street riding or unles the person wantsto execute a peg grab), and will generally run only a rear u-brake. Also, the tires will be treaded, as opposed to the slicks and semi-slicks used for park riding. Large, padded seats are also popularas something to land on when a trick fails, and are also easier to hold for in-flight tricks; but very small seats are also a style for those who know that seat size isn't really an issue. The gearratio is generally around 44:16, 36:13, 33:12, 30:11 or 25:9 though using small gearings like 25:9, known as 'micro gearing', has become popular in the present day.
* Hybrid BMX/Jump bike - ascaled up BMX with 24" wheels. Strong alloy rims and lightweight chromoly frame. Suited to bigger jumps or more challenging competition courses.
* Freestyle Motocross (FMX, Moto-X) of various sizes& engine sizes.

A typical dirt jump-mountain bike.
* Dirt Jump/Freestyle mountain bikes look similar to mountain bikes but have a rigid frame and, a lower stand-over height, this keeps the seatout of the way while performing tricks. The wheels are usually more robust than a cross country mountain bikes and the same for the frame. Frames are built for a balance of strength and lightweight.* Mountain bikes - 24 or 26 inch wheels and either rigid forks or forks with short front end suspension (usually 80–100 mm travel, but can be up to 203 mm depending on the type of the bicycle)...