A square wheel is a wheel that, instead of being circular, has the shape of a square. Such a wheel can roll smoothly if the ground consists of evenly shaped bumps of the right size and curvature. Stan Wagon , a mathematician at Macalester College, has constructed a bicycle with square wheels, together with a special track for riding it on.

For other improbable wheels, see Reuleaux polygon.

External link

• Math Trek: Riding on Square Wheels, Science News Online - contains illustrations and photos of Wagon's bicycle