Description:The Shimano Saint M815-2 Crankset is designed for two chainrings and a bashguard. The plated aluminum rings are 36/22. The rings are pinned, ramped, and profiled for better shifting. The bashguard is made from resin. The bolt circle diameter is 104/64mm. The chainline is 57.5mm. Shimano recommends their Super Narrow HG 9-speed chain with the chain rings. The crankarms utilize Hollowtech II technology. The right arm is permanently affixed to a hollow bottom bracket spindle. The bottom bracket, which is included, is the SM-BB80, and is designed to work with 83mm bottom bracket shells.