e*thirteen Helix Core e*spec Crankset - 170mm BOSCH CX Gen4/SX-Brose S Mag-TQ HPR50 26mm Offset Black. Helix Core e*spec cranks give your e-bike an upgrade with high-end integrity and aesthetics at a great value. Engineered for e-MTB strength so you don’t need to worry about pedal strikes or holding back on your next gravity run. Forged aluminum arms keep you confident on the trail while alloy self-extracting crank bolts mean efficient routine service and minimum added weight. Added details like pedal washers molded impact boots and e-rider preferred shorter lengths deliver all the high-end features youd expect from a crankset well over its price.