Wyoming. Criteriums are races based on circuits typically less than a mile in length and sometimes run for a set time (60 min, 90 min, etc.) rather than a specific distance. Criteriums are the most popular form of road racing in North America. In Belgium, kermesses are popular, single-day events of usually over . As well as road races in which all riders start simultaneously, individual time trial and team time trial events are also held on road-based courses. Track cycling Track cycling has been around since as early as 1870. The riders competed on wooden indoor tracks that closely resembled the modern velodromes of today. Unlike road racing, which is dependent on environmental factors, indoor tracks ensure the sport can be competed all year round. It encompasses races that take place on banked tracks or velodromes. Events are quite diverse and can range from individual and team pursuits, two-man sprints, to various group and mass start races. Competitors use track bicycles which do not have brakes or freewheels. Cyclo-cross Cyclo-cross originated as a sport for road racers during the off season, to vary their training during the cold months. Races typically take place in the autumn and winter (the international or World Cup season is September–January) and consist of many laps of a course featuring pavement, wooded trails, grass, steep hills, and obstacles requiring the rider to dismount, carry the bike and remount in one motion. Races for senior categories are generally between 30 minutes and an hour long, the distance varying depending on the conditions. The sport is strongest in traditional road cycling countries such as Belgium (Flanders in particular) and France. Mountain bike Mountain bike races are held off-road and involve moderate to high degree of technical riding. There are several varieties; the main categories are cross-country, enduro and downhill but also 4X or four-cross racing. BMX BMX takes place off-road. BMX races are sprints on purpose-built off-road single-lap tracks, typically on single-gear bicycles. Riders navigate a dirt course of jumps and banked and flat corners. Cycle speedway Cycle speedway is bicycle racing on short outdoor dirt tracks, in length. Motor-paced racing Motor-paced racing and keirin use motorcycles for pacing, so cyclists achieve higher speeds. Gravel racing Gravel racing is one of the newest disciplines of bicycle racing, emerging in the 21st century. For example, one of the premiere gravel races, Unbound Gravel, started in 2006. Some