My square-wheel bike, which used to be on permanent display at Macalester College. This construction, believe it or not, earned me an entry in Ripley’s Believe It or Not ® (see their depiction here); beats standing in a block of ice for three days or growing three-foot long fingernails. This version is our second such vehicle, built in 2004. The first, from 1997, was a little less refined and the ride on the catenary road less smooth. The new version rides very very smoothly. See also: https://www.macalester.edu/mscs/about/physicalmath/
In 2022 the Cody Dock rolling bridge in London was completed. It uses the idea of a rolling square to create a 27,000-pound bridge that can be rolled to an upside-down by hand. More information about this amazing structure is at:
