Street
Street riding involves maneuvers on obstacles that are typically man made and not designed for bicycles. They can be, but are not limited to, stairs, handrails, ledges, curved walls, banks, unusually shaped architectural designs and even a simple curb.
Through online surveys and magazine polls, it has been found that a large percentage of riders today participate in this discipline. As in the other forms of freestyle riding, there are no specific rules; style/aesthetics, skills, and creativity are stressed. Street riders tend to have no brakes if they do it is mostly straight cable not gyro. Usually they have front and back pegs on one side of the bike. They also have a tendency to ride without flanges on their grips. Some people like this because the flange gets in the way when they are doing a bar spin trick. Others mostly just like it because of the clean look.
Park
Skateparks are used by BMXers as well as skateboarders, inline skaters and freestyle scooter-riders. Skateparks themselves can be made of wood, concrete or metal. Styles of riding will depend on the style of the parks. Wood is more suited to a flowing style, with riders searching for gaps, and aiming to air higher from the coping. Concrete parks usually tend to contain bowls and pools. However, it is not unusual for riders to merge the two styles in either type of park.
Concrete parks are commonly built outdoors due to their ability to withstand years of exposure to the elements. Concrete parks are also often publicly funded due to their permanent and costly nature. Parks made from wood are popular with commercial skateparks due to ease of construction, availability of materials, cost, and the relative safety associated with falling on wood instead of concrete. Parks designed with BMX use in mind will typically have steel coping that is less prone to damage than concrete or pool coping.
Vert
Vert is perhaps the most extreme of the freestyle BMX disciplines. A half pipe consists of two quarter pipes set facing each other (much like a mini ramp), but at around 10–15 feet tall (around 2.5 to 3.5 metres) high. The biggest ramp ever used in competition is the X-Games big air ramp at 27 feet tall. Both ‘faces’ of the ramp have an extension to the transition that is vertical, hence the name. Coping is a round metal tube at the lip of the vert that helps freestyle BMXers do grinds, and stalls on the lip of the vert.
Riders go up each jump, performing tricks in the air before landing into the transition having turned 180 degrees (assumptively. variations include 540, 900). A typical run involves going from one side to the other, airing above the coping each side. Also possible are 'lip tricks' - tricks on the platform at the top of the ramps before dropping into the ramp.
Trails
Trails are lines of jumps built from dirt (heavily compacted mud). It can also be named as a pack such as a 4 pack, 6 pack and 8 pack. The jumps consist of a steep take off, called a lip, with an often slightly less steep landing. The lip and landing are usually built as separate mounds, divided by a gap. The gap is measured from the topmost part of the lip, horizontally to the topmost part of the far side of the landing. Gaps typically range from only a couple of feet to over twenty feet. A moderate gap is around twelve feet.
Trails riding is sometimes also referred to as “dirt jumping”. Most trails riders maintain that a subtle difference exists in the style and flow of “dirt jumps” and “trails”; trails riders focus more on of a flowing smooth style from one jump to the next while performing more stylish tricks, while dirt jumpers try to perform the craziest tricks they can over larger, less flow-oriented jumps.
Although many regard trails and street as being completely opposite, the attraction is similar — trails riders build their own jumps so their riding is limited only by their creativity and resourcefulness.
Trails riders usually run a rear brake only as they have no use for a front brake, and usually a rotor (gyro) to make it easier to do barspins, as they do not have to spins the bars back the other way to untangle it, which is hard to do on trails. In general, trail/dirt jumping bikes have longer wheelbases (chainstays) than other BMXs to aid with stability.
Flatland
Flatland BMX occupies a position somewhat removed from the rest of freestyle BMX. People who ride in the above disciplines will generally take part in at least one of the others, but flatlanders tend to only ride flatland. They are often very dedicated and will spend several hours a day perfecting their technique.
Flatland also differs from the others in that the terrain used is nothing but a smooth, flat surface (e.g. an asphalt parking lot, basketball courts, etc.). Tricks are performed by spinning and balancing in a variety of body and bicycle positions. Riders almost always use knurled aluminum pegs to stand on to manipulate the bike into even stranger positions.
Flatland bikes typically have a shorter wheelbase than other freestyle bikes. Flatland bikes differ from dirt jumping bikes and freestyle bikes in one way. The frames are often more heavily reinforced because the people riding flatland often stand on the frames. This shorter wheelbase requires less effort to make the bike spin or to position the bike on one wheel. One of the primary reasons flatlanders often ride only flatland is the decreased stability of a shorter bike on ramps, dirt and street.
A variety of options are commonly found on flatland bikes. The most unifying feature of flatland bikes is the use of four pegs, one on the end of each wheel axle. Flatland riders will choose to run either a front brake, a rear brake, both brakes, or no brakes at all, depending on stylistic preference.
source: wikipedia
