A cyclo-cross bike or cyclo-cross bicycle (abbreviated CX Bike or CXB) is a bicycle specifically designed for the rigors of a cyclo-cross race. Cyclo-cross bicycles roughly resemble the racing bicycles used in road racing. The major differences between the two are the frame geometry, and the wider clearances that cyclo-cross bikes have for their larger tires and mud and other debris that they accumulate. Cyclists have been competing in races on road-going bicycles since the 19th century. Cyclo-cross emerged as a sport in its own right in France in 1902. Cyclo-cross bicycles are similar to other bicycles, but the frame geometry is closer to a mountain bike than a road racing bicycle. The top tube is often longer and closer to horizontal, and the handlebars are higher, again akin to mountain bikes. The emphasis on bicycle handling skills differentiates cyclo-cross from road racing. Cyclo-cross courses are held on a variety of terrain, including grass, mud, sand and paved surfaces. History There are many stories about the origins of cyclo-cross - and so about the origin of cyclo-cross bikes. What can be assumed to be certain is that the cyclo-cross bikes are a further development of normal racing bikes, which have been adapted to the needs of cyclo-cross sport. Today, they are often described as having a mixture of mountain bike and road bike characteristics, but in fact existed decades before mountain bikes were introduced in the bicycle world. The first explicit cyclo-cross bicycles appeared in the 1960s, manufactured by European companies from the Netherlands, Belgium and Italy. At first the frames were usually made of steel; nowadays, aluminum and carbon fibre are more common, at least in regard to cyclo-cross bikes built for racing. Characteristics Frame design Frame materials are selected with an aim to produce a lightweight, yet stiff and responsive frame. Low weight is prized for ease of carrying while running. Cyclo-cross racers may lift or carry their bikes as many as 30 times in one 60 minute race, increasing the desire for a lightweight bicycle. Aluminum frames were popular in cyclo-cross bicycles long before they became commonplace on the road. Today the most popular material is aluminium with carbon fiber being popular at a professional level. Cyclo-cross frames require clearance for slightly wider (generally 30–34 mm) tires and the debris and mud that is picked up by them. They are typically very simple, often eschewing bridges between