Motocross (or MX) is the direct equivalent of road racing, but off road, a number of bikes racing on a closed circuit. Motocross circuits are constructed on a variety of non tarmac surfaces such as dirt, sand, mud, grass, etc., and tend to incorporate elevation changes either natural or artificial. Advances in motorcycle technology, especially suspension, have led to the predominance of circuits with added jumps on which bikes can get airborne. Motocross has another noticeable difference from road racing, in that starts are done en masse, with the riders alongside each other. Up to 40 riders race into the first corner, and sometimes there is a separate award for the first rider through (see holeshot). The winner is the first rider across the finish line, generally after a given amount of time or laps or a combination.