are now regularly held in the fall and winter seasons throughout the United States and continue to grow in popularity. Racing seasons Cyclocross is typically an autumn and winter sport, the northern hemisphere season running from September to February. The World Championships take place in late January. The Canada championships are held in November with the US and UK championships held in January. In the United States, there is little racing after that except in states with year-round warm climates such as Florida and California. The cyclocross racing season within southern hemisphere nations typically runs from May to August. Riders' age categories for cyclocross under UCI rules are currently determined by their age on 1 January which lies in the middle of the international season, i.e. they compete in the same category that they would be in for the following road season. Equipment Bicycles Cyclo-cross bicycles generally resemble road racing bicycles. Cyclo-cross-specific frames differ with their wider tire clearances, knobby tires, cantilever or disc brakes, and lower gearing. Cables are generally routed on the upper side of the top tube, which allows the rider to carry the bike comfortably on the right shoulder through portage sections, and prevents cable contamination by dirt. Popular on many cyclocross bikes is routing the brakes so that the right brake is often the front brake. This is done to allow the left hand to control speed while approaching obstacles requiring the bike to be carried, while the right hand grips the frame ready to lift the bike onto the shoulder as soon as the rider's feet touch the ground. As a high-end bicycle purpose-built for a specific sport competition, they also differ from ordinary "hybrid or trekking" cross bikes, which are general-purpose utility bikes fitted with slightly wider 700C tires for use on unpaved paths or trails. Cyclo-cross bike design and frame geometry has evolved over the years. The first cyclo-cross bikes were touring-type road bikes, used for their cantilever bosses, slacker angles and wider tire clearance. Over time as the sport became more formalized, frame angles changed for quicker handling and bottom brackets heights were raised to clear broken ground. Most cyclo-cross frames have a non-compact (flat or near-flat top tube) frame design for easier shouldering. Some design features have recently begun to change, for example, a heightened bottom bracket was typical 10+ years ago; now many cyclo-cross-specific frames do not have elevated