Dirt bikes are motorcycles designed for off-road travel for the “weekend warrior” as one dirt bike magazine described their clientele. They look something like a motorized mountain bike with a stout suspension system to absorb the shock of travel over rough terrain, along with knobby tires for gripping loose gravel, sand, and mud. Like snowmobiles, dirt bikes come in a variety of types including motocross, euduro, trail, and others depending on the usage.
Motocross is basically a racing cycle. Under American Motorcycle Association rules a motocross race takes place on a closed half mile to one and a half mile long course with hills, jumps and irregular terrain. Euduro motorcycles are used in race meets where speed is not the ultimate factor in who wins. Enduro races may be as much as 100 miles in length. At the light end of the motorcycle spectrum are trails that are lightweight machines equiped with rugged tires for riding on unpaved ground and trails.
Dirt bikes cause significant soil erosion and compaction, increase sedimentation of streams and damage fragile ecosystems particularly in deserts.
Dirt bikes, which are generally equipped with narrow tires that can create ruts that eventually, erode into gullies. Erosion depletes top soil and contributes to stream sedimentation, which destroys critical habitat for a wide array of fish, including salmon and trout.
Dirt bikes spread noxious and invasive weeds which crowd out native plants, alter natural habitat and adversely impact farmers and ranchers. Based on research by the Montana State University Extension Service, a single dirt bike or ATV can spread 2,000 seeds over a 10-mile radius.