A number of extreme sports are being practiced in Australia, sports such as BMX racing, skateboarding, mountain biking. But the most common is BMX racing which has been sweeping the nation, there are many diverse ways that you can ride a motocross bicycle that range from dirt racing to skatepark stunts and tricks. There are four specific riding disciplines that you can see, and specific bike sizes and types that are used in these disciplines.
Park riding, it's done in skateparks, and a variety of indoor ramps that riders use to do various tricks and stunts. The second discipline, street riding, it's similar to park except as its name would suggest the tricks are performed on stairs rails, benches whatever the riders want to attempt. Flatland is quite niche as far as disciplines go, it's tricks done by the rider and only the bicycle, it's akin to breakdancing and is usually done with cruiser bikes, but more on the bike types later. Dirt Jumping and trails are purpose built ramps that riders use specifically to get big air and do large jump stunts. And the final discipline is race, which is done on purpose built courses which often feature undulating terrain.
The size of the bike is based on two factors, the size of the wheel's diameter in inches and the length of the frame. Most bikes range from 15 to 29 inches, usually you won't see these two sizes but the mid-range bikes are what you'll be seeing more often. A 20 inch bike is the standard where the rider can reach the pedals BMX that has 20 inch wheels is large enough for an adult to ride it with complete flexibility and relative speed. Anything above 20 inches is a cruiser bike which is primarily used for flatland tricks and has its own category for racing. But most pros will build their own custom bikes out of parts they order such as handlebars, frames, wheels, stem, seat, cranks, pedals BMX specific gearing and the one break. Assembling your own custom bike is simple enough, you need to ensure that all of your components fit, then all you need is the knowledge if where they go and the tools to fit them.
There are skate parks in most cities so there's always somewhere where you can practice tricks or have races with some friends. And practice is what you will need if you're planning on only doing tricks, even though the bike is fairly flexible it still takes some finesse to pull off tricks and jumps.
