this site has some good info on the spiral bevel gears. If you scroll down to the section on them, it has a diagram which describes (and even shows how to calculate) the loads that would be created.
The force they mark as Fp will be what will probably require a thrust bearing to compensate for. This would be placed between the face of the motor (or the plate that the motor mounts to) and the pinion itself. It's job is to take that load and apply it to the face, so that the shaft isn't taking that load.
You'll see the Force Fs also applies a small amount of thrust loading, but more so, pushes normal to the shaft. Depending on how large this is, you may need to support the end of the CIM shaft with a normal bearing. Supporting it at the face of the CIM would do a little bit, but not very much. I would assume you need to support it on end.