The Samox AF29 crankset is optimized for trekking bikes and features forged aluminum crankarms that mate with a JIS Square Taper spindle (bottom bracket and spindle bolts are sold separately. JIS Square Taper Spindle interface (Bottom bracket and spindle bolts sold separately) Designed for use with 9-Speed drivetrains Rigid and lightweight forged aluminum crankarms 48t outer chainring is stamped aluminum for weight savings 36t middle and 26t inner chainrings are stamped steel for durabity and long life 104/Riveted BCD 4-Bolt chainrings 50mm chainline achieved with 118mm spindle length MfrPartNo:AF29-338ASS-175 Rings:48/36/26 Number of Chainrings:Triple Drivetrain Speeds:9 Chainring BCD:104 Chainring BCD:Riveted Color:Black Crank Length (mm):175 Crank Intended Use:Commute BB Included:No Pedal Spindle:9/16" Spindle Interface Type:Square Taper JIS