The Helix R is e*thirteen's top-of-the-line aluminum alloy crank. Forged AL-6066-T6 arms deliver Enduro strength in XC weights and it took a 30mm Forged 7050-T7 spindle and massive amounts of CNC work to get there. CNC detail can be seen all over every surface for the ultimate in tech bling and weight savings for your ride. Designed to be compatible with Shimano™ and SRAM™ drivetrains, modern hub spacing, and bottom brackets. Helix R cranks can achieve boost and super boost chainlines with their flip-flop chainrings (Sold Separately).