Powerwheel was an an attachment that created a motorcycle out of a bicycle. Designed in 1951 by Cyril Pullin, it was intended to be built and sold by Tube Investments.
This was an unusual and clever design, as the attachment was meant to replace the rear wheel of a bicycle. The unusual feature was the 40cc two-stroke rotary engine in which the crankcase stayed still and the rest revolved around it. It was a complicated affair that made the porting, balance and other normally simple tasks difficult.
Source: Graces Guide
