Square Wheels, Round Road? 

From Science News Online...


Bicycle Riding on Square Wheels.

This is no joke, but it does take a road with a very specific shape which the article explains. Apparently its very difficult to turn, but the article goes on to describe that you can come up with a roadbed to suite almost any shape wheel... except for a triangle (I originally thought the opposite when I was talking with people at work about this). Its just another example of what happens when a mathematician has too much time on his hands.