Published in ScienceNOW, 14 Apr 2011
Give a riderless bike a push, and chances are it will cruise along for a bit without tipping over. Scientists have long thought they understood the physics of what keeps the bike upright. But a new study shows that much of what they believed is wrong.
Researchers assumed that two mechanisms kept a riderless bike upright. First is the “caster effect,” which relies on the position of the front wheel relative to the steering axis—the imaginary line that extends from the front forks downward. On most bikes, the front wheel meets the ground just behind this axis, so it tends to center itself like the casters on a shopping cart. The other mechanism is known as gyroscopic precession: Because the front wheel is spinning forward, any tilt to the left or right creates a force that will steer the bike in that direction, pulling it out of the fall. […]
The rest of this article is available here.