E*Thirteen Helix Core E*Spec Bosch CX Gen4/SX Brose S Cranks An E-Bike Drivetrain Upgrade The Helix Core cranks provide an e-bike drivetrain upgrade with high-end features and aesthetics at an exceptional value. Forged for e-Enduro strength, with alloy self-extractor bolts, pedal washers, and molded impact boots. 24mm ISIS interface models are compatible with Bosch Gen 4, Brose S Mag, TQ, Fazua, Yamaha, Maxon, and Specialized Brose motor systems. It is available in short lengths from 155mm for improved pedal clearance. Features Material: forged, CNC-machined AL-6066-T6 arms Compatible with 24mm ISIS spindles Available in short lengths from 155mm for improved pedal clearance SPECIFICATIONSSpeeds11/12-Speed BB Compatibility24mm ISISChain Ring Sold Separately Crank Arm Length155, 160mm BB Spindle Interface24mm ISISChainring Material N/ABolt Center Diameter (BCD)-Crank Arm Material Forged, CNC Machined AL-6066-T6Chainline21. 5mm or 26mm Offset Bottom Bracket Included No Intended Usee-MTBWeight- | E. thirteen | Helix Core E*spec Bosch Cx Gen4/sx Brose S Cranks 160Mm Offset Blk 21. 5Mm Offset | Aluminum