Universal Torque Arm
The Universal torque arm works for more or less any bicycle type. The axle head fits over the motor axle, and then the arm section screws into it, and reaches to the nearest position on the bicycle (e.g. the bicycle forks) where the clamp is tightened.
It is important to tighten the clamp fully to ensure that all of the torque is transferred through the arm and that there is no flexibility.
The only disadvantage of this option is if no protective rubber or other padding is used, the hose clamp can scratch the frame. Also it is less neat than the eyelet style arm because of the extra part (the clamp).