Well, I'm building a two person pedal car, and i need a way of connecting an aluminium bike wheel to a steel axle. I don't have a welder, but since they are two different metals i couldn't weld them together anyway. It needs to be on about halfway down the axle, and it has to rotate with the axle. I also need to attach a regular bike gear next to it, also rotating with the axle. How should i do this?
Also, i need to attach two more bike wheels to the side of the frame, so they are parallel, and so they don't tip inwards when weight is put onto them.

So, how do i connect a gear and a wheel to an axle halfway down, and how do i connect wheels to the side of a thing of wood?