All Riders come with two key ways cut into the back axle.  One is for the brake and the other is there if you want to put a motor on it.

As you see we put a metal platform to hold the motor with space to hold our baskets to carry things.  The metal sheet and motor is something you install.  We used simple U bolts to hold the metal, this allows us to take it off if needed.  You can weld it onto the frame, or bolt it right through the frame.  That's the beauty of Railriders, there is so much you can do with it once you get it.