Choices of equipment tend more towards the idiosyncratic than in road racing; for example single-speed bicycles also have some popularity due to the advantage of mechanical simplicity in the often very muddy conditions and the fringe nature of the sport. Gearing is typically lower, with most common setups using a 46-36 (110mm BCD) or 48-38 (130mm BCD) chainring combination with a 12-25 to 12-30 cassette. Some riders opt to use a single chainring in the front (typically a 40-42 tooth chainring) while retaining multiple sprockets in the rear cassette. This has some of the advantages of the single-speed: the weight of the front derailleur and the front shift lever are lost, a single chainring allows for a tighter chainline, thus reducing the chance of throwing a chain on a bumpy course, and further, racing is psychologically simpler.