SRAM RED 1x XPLR Wide Crank Arm Assembly - 172.5mm 13-Speed 8-Bolt Direct Mount DUB Spindle Natural Carbon E1SRAM RED 1x XPLR Wide Crank Arm Assembly 172. 5mm 13 Speed 8 Bolt Direct Mount DUB Spindle Natural Carbon E1. When SRAM found ways to make their lightest and stiffest crank even lighter they went for it. A new process further grams from the hollow carbon arms. Plus theyre offering more crankarm lengths than ever before to ensure this crank works for you. Hollow carbon crank arms are 29g lighter than previous generation 8 bolt interface compatible with