OK so I finally took some measurements. The wheels are about 12 1/2" in diameter and the chain is 1/4" pitch. So the chain is exactly 1/2 scale but the wheels are a little smaller then that. The chain is a manufactured item. You can get drive chains in many different sizes from industrial transmission suppliers. My guess would be that Dick made the rims out of something that was "close enough"...
Jamie Swan Cell - 516-238-6782 Centerport Cycles Inc. 245 Main St. Northport, N.Y. 11768 631-262-0909 http://www.centerportcycles.com (mapped) http://www.cabinfeverauctions.com http://www.cabinfeverexpo.com http://www.limws.org http://www.liatca.org