These Forged AL-6066-T6, CNC-sculpted aluminum cranks are designed for the rigors of downhill, big bike park laps, enduro, and freeride. The Helix Race GR shares the spindle design and low-profile shape with our top-end carbon and alloy cranks, with 83mm and 73mm spindle options. Helix Race GR cranks easily exceed ASTM 5 standarda work of art made to take a beating.Exceeds ASTM 5 standards for Downhill, Bike Park, Enduro and Freeride applicationsForged, CNC Machined, AL-6066-T6 arms and 30mm AL 7050-T7 spindle73mm and 83mm spindle options for enduro and DH bikesAvailable in popular gravity crank arm lengths, 160mm and 165mmMolded crank boots, protective polymer decals, APS adjuster, and self-extractor system included83mm crank requires the Helix GR Chainring. 73mm crank requires a standard Helix chainring.