Complex sentence: The five circuits (one each representing Europe, Africa, Oceania, Asia, and the Americas) comprise a series of races in which, as in the UCI ProTour, to which the circuits are inferior, various cycling teams compete regularly.
Split into simpler sentences: The five circuits (one each representing Europe, Africa, Oceania, Asia, and the Americas) are inferior to the UCI ProTour. Both the ProTour and the circuits comprise a series of races in which various cycling teams compete regularly.