Kevin

You should support the rear of the shaft. My rear support came loose one time and the motor/airframe shook and shimmied until I throttled back. I had reinforced the nose with 3 layers of carbon cloth for a little added insurance. This was on a Prestige with a A60-20S. The rear of the shaft takes a 10mm ID bearing. On the newer motors the shaft is a little oversize so you might have to sand/file the shaft down a little.

The rear shaft only projects from the rear of the motor about 1/16" so you have to mount the bearing as close to the motor as you can in order for the shaft to ingage the bearing.

Here are some pictures of the set up.