RaceFace Turbine Fatbike 170mm Black Crank Arms for 190mm Rear with 120mm Bottom Bracket Arms are carefully engineered using ultra high-strength AL-7050 alloy to maximize strength-to-weight ratio Forged for maximum fatigue resistance and then extensively CNC-machined Butted, forged and CNC-machined chromoly Exi spindle Exi interface allows easy installation and removal Cranks allow use of either 9- or 10-speed chainrin