Triangle-Wheeled Bike Gives New Meaning to ‘Tricycle’. The inventors

… went back to the drawing board to see if they could come up with a bike design featuring triangular wheels. They succeeded, and unlike the square-wheeled bike, these triangular wheels actually roll like round ones.

This is known as the Reuleaux triangle. I first ran across it in Poul Anderson’s 1963 SF story The Three Cornered Wheel, which I read sometime in high school (1964-68). A stranded spaceship crew needs to transport a heavy object over land. Unfortunately, the use of anything circular for mundane purposes is forbidden by the religion of the natives. However, the use of a curve of up to 1/3 of a circle is allowed for a sufficiently important cause. The young hero figures out that using such a “three cornered wheel” will solve the crew’s problem without offending the religious authorities.