BMX: True BMX bikes started it all, back in the late sixties. They were knockoffs of motocross motorcycles and were designed for racing over jumps and around berms in the dirt. Pretty soon kids everywhere had them, racers or not. BMX bikes are still designed for racing, although you don't have to race to enjoy the light weight, speed and dirt worthiness of these machines. They usually have 20-inch wheels (24-inch-wheel cruisers are the exception), knobby tires, upright handlebars with crossbars, small saddles, long cranks and rear hand brakes. The frames are light and sturdy, and the higher the price, the lighter they get.
Freestyle: These entered the scene shortly after BMX bikes. Rather than racing, the freestyle bike's ideal use is for flatland tricks, aggressive street riding and getting vertical at skateparks. It's also a great bike for riding to school, the store and the pool. Super-sturdy construction is a higher priority than light weight. The wheels are usually either mag wheels made of sturdy nylon (far left in the photo below), or heavy-duty models with 48 wire spokes. The tires are 20 x 2.125 or wider, with fairly smooth treads, because they're predominantly pavement pounders. Axle pegs are often included (riders stand on them for stunts), although some manufacturers leave them off so you can choose your own. Freestyle bikes come with front and rear brakes. The front cable is routed through a rotor or detangler, which allows the handlebars to be spun completely around without tangling the brake cable.
Dirt Jumper: As the name implies, dirt jumpers (also known as jumpers) are designed for taking flight. They also bridge the wide gap between BMX bikes and freestylers (beefier than the former; lighter than the latter). They usually don't have front brakes and their brawny wheels normally feature 36 rugged 13-gauge spokes, rather than resorting to 48 spokes the way freestyle bikes do. They are occasionally equipped with 24-inch wheels, which are a great choice for larger riders. The tires are the most heavily treaded of any of the BMX types.
Wheels: It's crucial that the wheels meet your needs. Because accelerating out of starting gates is important in BMX, the wheels are much lighter than those found on freestyle or jump bikes. However, that 32-spoke light aluminum wheelset designed for BMX racing won't hold up to dirt jumping or ramping. So, freestyle bikes come almost exclusively with 48-spoke or mag wheels. This makes them ultra-beefy for maximum rim protection. Dirt jumper's wheels tend to be a bit more varied. Some dirt jumpers are equipped with just 36 super-meaty 13-gauge spokes. Others come with 48 spokes like freestyle bikes, depending on whether the bike is geared more for jumping or dirt riding. It's also important to note that the skinnier BMX tire and rim sizes (20 x 1 1/8-3/8 and 24 x 1 1/8-3/8) are not interchangeable with each other or with the 20 x 1.5 or 1.75 tire and rims.
