Re: Is this really worth it?
I added a rear disk brake to my mountain bike (non-motorized) with an A2Z adaptor. The disk brake helps a lot on muddy trails. I only ride my motorized bike on the street. I don't think the rear disk brake is worth the money and effort on a motorized bike unless it is friction drive or driven by pedal chain through a shift kit. It is a very tight fit with the motor chain and disc caliper on the same side.
“You're only young once, but you can be immature as long as you like" -Unknown