You can definitely screw it up if you try to convert the existing rear wheel. Redishing and screwing around with the freewheel threads are two potential danger areas.
Also, the sprocket can come off while you're stopping. In addition to the risk of death or injury, the threads will almost certainly be screwed up if you force off the sprocket against a lockring.
Last edited by garage sale GT; 06-30-09 at 07:26 AM.