Possibly the future of a rather limited sort of transportation anyway.
Back story: I was soliciting for a bicycle to be used as a parts donor for a different project and I got a Mongoose (Wal Mart) 26" metrosexual off road bike. Turned out to be unsuitable for the original project, but it cleaned up enough to be rideable. Also some 2 winters ago my old snow blower fell apart and I replaced it. Being me, I removed the motor which still ran well, before tossing the rest.
In my second retirement I got bored and got looking at the junk lying about and voila! instant project.
When I was in Saigon, the commonest form of motor transport was a cruiser frame bicycle with a small 2-stroke motor mounted to the handlebars. When a large lever was pushed forward, the crankshaft was pressed against the front tire, and the motor pulled the bike along at 15-20 mph. The motor assembly was from Solex, famous maker of French carburettors. The exhaust pipes were quite long and extended almost to the pavement so as to keep ones clothing from getting a layer of oil on it.
Kits like this would be illegal in the U.S. with the 2-stroke motor, but there are similar kits that mount to the rear wheel and use 4-srtoke motors available at what I think of as exorbitant prices. My old blower was a 2-stroke, but I have access to specially blended oils that burn very clean.
2 nights work, and I've got the motor mounted:
This post qualifies as a Mad Science post which is a happy change from bitching about politics in an election year. I need one of these like a hole in the head, but as I mentioned earlier: boredom.