And then there are those efforts to create two wheel enclosed motorcycles with retractable landing gear, from the Monotrace Cabriolet of 1925

to the "ecomobile"...

http://www.detnews.com/2005/autosinsider/0501/30/autos-73731.htm

... with a number of variants in between.

I always liked the idea of a retractable wheel motorcycle, although frankly I'd be terrified to drive one.

The Eco-Mobile is interesting, but at 1200cc and $80,000, it's a bit of an overkill.

oh, I agree... it's absurd. (But cool!)

And that Montrace Cabriolet was an excellent find.