Crank arms on eBikes transmit both rider pedal force and (on mid-drive bikes) motor torque into the drivetrain — requiring durable construction and compatibility with your motor's bottom bracket interface.
What crank arm length is best for an eBike?
Standard crank arm lengths (170–175mm) work well for most riders on eBikes. Longer cranks (175–180mm) provide slightly more leverage for climbing but can reduce ground clearance on technical trails. For mid-drive eBikes, use the crank length recommended by the motor manufacturer to avoid compatibility issues.
Are standard crank arms compatible with mid-drive eBike motors?
Mid-drive motors like Bafang BBS01/BBS02/BBSHD use a proprietary bottom bracket that requires compatible crank arms. Bafang-specific crank arms with the correct spline interface and bolt pattern are required. ENVO's mid-drive kits include compatible crank arms in the package.
Do hub motor eBikes need special crank arms?
Hub motor e-bikes use a standard bicycle bottom bracket and can use any standard crank arm compatible with the bottom bracket interface (square taper, Hollowtech II, etc.). No special crank arms are required for hub motor conversions.
When should I replace eBike crank arms?
Replace crank arms if the pedal threads are stripped, the arm is cracked or bent, or the bottom bracket interface (square taper bore or spline) shows significant wear. Crank arm failure under motor torque can cause a sudden drivetrain seizure — inspect regularly on high-mileage e-bikes.
What is the torque spec for eBike crank arm bolts?
Square taper crank arm bolts should be torqued to 35–40 Nm. Bafang proprietary crank bolts have specific torque specs listed in the motor manual. A proper torque wrench is essential — undertightened crank arms can destroy the bottom bracket interface. Browse our tools collection for compatible torque wrenches.