http://anarchadia.blogspot.co.uk/2012/08/vintage-thing-no117-skr-imp-powered.html
One for them that like odd vehicles
Jacko

If the 2 (rear) wheel centres are within a certain distance apart they are deemed to be a single wheel. Check out Owen Greenwood's mini from the 60's. It was very successful until banned!

Without getting my ruler out, that would be classed as a trike.

So if you did the same trick at the front and the back could you make a 4 wheeled "bike"?

Or can you only use the trick at one end?

I know that having the two wheels close enough together means that it is legally classed as a trike, but am I right in remembering that a 2CV based kit, with both rear suspension arms swapped over brings the wheels close enough together?

The tread centres of the twinned-wheels must be less than 46cm apart.

A 2 speed 3 wheeler................Didn't Morgan move on from that about 80yrs ago............

There are 3 wheeled scooters available like the Piaggio mp3. They look weird at first but when you see one running round they make sense.