 World champions wear their rainbow jersey until the following year's championship, but they may wear it only in the type of event in which they won it.First held in 1950 it replaced the Critérium International de Cyclo-cross (French for "International Cyclo-cross Criterium") which, as the first international cyclo-cross race, was considered the unofficial world championship.It has since been held annually and is traditionally disputed at the end of January or the beginning of February.