Well, I'm a long term dreamer, but I'm making hard plans to get a powered bike on the road. UK Single Vehicle Approval is fairly easy for sub 1kw power engines. I intend using a minimoto and 4:1 reduction box on a basic mountain bike.
It's good to see what other people are doing though, helps avoid too many mistakes. I had thought about a roller drive off a strimmer engine, but I'd prefer something the inspector would recognise as Proper Engineering, although there's somebody here with a racing cycle and direct drive which looks rather smart.
Also, my friend JC is intending to use a GX140 clone engine in a bike, so I'm not alone in this venture.