FSA SL-K Light BB30 Double Chainset: The SL-K Light carbon fibre chainset is manufactured using the same hollow carbon molding process FSA pioneered with their K-Force Light crankset. The main benefits of the hollow carbon construction are simple: Stiffness & weight savings. Youll also feel zero crank flex. Fitted to the arms are a pair of Semi solid AL7075 100% CNC process chainrings secured by AL7075 Torx T-30 alloy chainring bolts. The SL-K uses a BB30 & has a Q-factor at 145mm & a chainline of 44mm means smooth shifting with 9 or 10 speed Sram, Shimano drivetrains. Shimano 10 speed AL7075 100% CNC process chainrings AL7075 Torx T-30 alloy chainring bolt Length: 170mm, 172.5mm, 175mm Q-Factor: 145mm BCD: 130mm Chainline: 44mm UD carbon finish Storm Grey Anodized chainrings finish Updated color graphics BB30 Oversized BB for super stiff, positive drive Rings: Double 53/39 Weight: Double 614g