SRAM XX Ebike Crank Arm Set - 165mm ISIS BlackSRAM XX Ebike Crank Arm Set 165mm ISIS Black. The XX Eagle E MTB Crank takes from its race winning lineage and is optimized for E MTB use. Carbon fiber engineered with a foam core to give both incredible strength and maximized stiffness under the high torque environment of E MTB. Paired with the new XX Eagle Transmission (T Type) direct mount chainring performance and design aesthetic blend together to provide our most premium performance driven crank