The Physics Of The Riderless Bicycle

If you push an unmanned bike forward, it will roll straight without falling over (for a little while, at least). Andy Ruina, a Cornell University professor of mechanical engineering and a cyclist himself, has spent the past 25 years trying to figure out why.

When you're riding, you think you're going in a straight line. But really you are falling to the right, steering to the right, falling to the left, steering to the left, and constantly making these corrections. The wheels have to be under the bike's center of mass to keep it upright. But if there's no person to do that steering, then it has to come from automatic effects. Cornell University in cooperation with Delft University of Technology in the Netherlands investigated what causes the bicycle to do this automatic steering.