Came across this photo a while back and thought you might like to see some original thinking in the motorcycle design field, this is the Monotrack Experimental built back in the early seventies by Dan Hanebrink.
The description on the Hanebrink site (no longer there) pretty much sums it up:
In 1971 "Cycle News" publisher Chuck Clayton asked Costa Mesa, California engineer Dan Hanebrink to sketch a futuristic machine of the eighties for a front page Christmas issue of the newspaper. From this sketch Hanebrink developed his ideas and the result, two years later, was the Monotrack Experimental. This design accounted for a large number of firsts in motorcycle engineering. The monocoque chassis was made from magnesium plate and a three-cylinder, rubber-mounted, two-stroke Kohler snowmobile engine provided power to the belt-driven torque converter. Drive to the rear wheel was also by belt. Hanebrink produced the 16-inch cast magnesium wheels on which Goodyear racing tires were mounted. The suspension had no springs, but relied on air and oil damping. The circular component on the fork bottom and rear strut contains a central neoprene diaphragm, which separates the oil and air. In use, the oil in the suspension struts compresses the air under load, allowing 41/2 inches of travel in the front forks and 4 inches in the rear.
So he whipped up this snowmobile powered, CVT transmission, belt driven, air and oil suspended, monocoque chassis motorcycle, based on a sketch and an idea. And they didn't have CAD and CNC machines to help, either. Neat!
Dan Hanebrink has been building quite a few interesting vehicles over the years including the "Ice Bike" used in a bicycle trip to the south pole, which is now his Extreme Terrain Bike which can be used on sand, snow or wherever else a regular bike can't go. Dan has done a little downhill bicycle racing, too, and of course there is the motorcycle business. Turn a guy loose with some tools and great ideas, and look what happens!