The lightest & strongest Octane One tubular cromoly crankset comes in a popular & trendy two piece format. Designed as a complete set dedicated for MTB frames with a unique external bottom bracket included. 170mm crank arms made of high quality seamless 4130 cromoly tubing with full heat-treatment. The 19mm diameter hollow axle with 48 micro-splines eliminates the need of pinch-bolts making this crank arm lighter and gives it a clean look. By moving the bearings out of the frame we are not limited to small weak bearings. We use strong Spanish BB 19mm bearings in external alloy cups and the result is wider and stiffer system w/o weight penalty. Right side sprocket mount only – this is a MTB set. Will accept any BMX sprocket with standard 15/16” or 19mm central hole and standard mounting hole (23t and bigger sprocket sizes). The chain line is perfect for MTB!