SRAM Rival 1x XPLR Wide Crank Arm Assembly - 172.5mm 12/13-Speed 8-Bolt Direct Mount DUB Spindle BLK E1SRAM Rival 1x XPLR Wide Crank Arm Assembly 172. 5mm 12 13 Speed 8 Bolt Direct Mount DUB Spindle Black E1. SRAM has taken aluminum to another level. Careful engineering has resulted in crankarms that optimize stiffness to weight ratio with material only where its needed8 bolt interface compatible with power and non power AXS spiders and integrated chainrings (Chainring and spider sold separately) DUB bottom bracket adds durability and simplicity