BMX and Jump Bikes
BMX bikes are the ultimate design with sporting bikes as they are specifically made to handle all that is involved with BMX racing also called motocross. BMX bikes are able to handle a variety of motocross terrains including vert, flatland, street, dirt and part (grass). They can come in a variety of metals but the affordable models come in steel but if you are in it to win it, you might want a BMX bike made of either aluminum (for speed), generation 3 or 4130 chromoly. If you just want a mid-grade model that is better than many racers have you can look for one made of hi tensile steel or simple chromoly instead.
Jump bikes, also called dirt jump bikes, are just what they sound like: for jumping. Jump bikes are mainly known for they reinforced frame and specific design that is meant to handle the biggest jumps you can just about think of. The wheel structure is different than any other bike because the very shape is designed to be more robust than most other wheels includes those of mountain bikes. A jump bike also stands slightly shorter when compared to a mountain bike or a street BMX bike because it allows the seat to be more out of the way when the rider is doing a trick.