Source: The Complete Motorcycle Book by Jim Bennet
Motocross racing used to be called "scrambling." Motocross is simply a race to the finish line. Everyone starts at the same time in one huge swarm and hopes they aren't crushed, side-swiped or run over. Motocross bikes are designed for "closed course" competition races. Closed course means that the route is fixed and on private land. As such, features that add weight, and would make a motocross bike legal for enduro riding are missing. These bikes are similar to enduro bikes and often have the following features: