Untied shoelaces are one of my biggest pet peeves. It doesn’t matter if they’re on my feet or somebody else’s, I am seized with the overcoming urge to double knot them so tightly only scissors will reverse the damage. So you can imagine my relief upon hearing that engineers have finally discovered why shoelaces are always coming untied. The first step to finding a solution is understanding the root of the problem, after all.
According to new research from the University of California, Berkeley, shoelaces come untied due to a combination of the force of your foot hitting the ground and the motion of your leg. These movements combine and create a perfect storm of shoe-untying misery.
The research was conducted by Oliver M. O’Reilly, a professor of mechanical engineering, and Christine E. Gregg and Christopher A. Daily-Diamond, students who are pursuing a Ph.D. in mechanical engineering. They spent a lot of time wearing different types of shoes and seeing how different types of motions affected shoelaces.
“We spent countless weekends walking up and down the hallways and staring at shoelaces, watching them coming apart,” Ms. Gregg told The New York Times in an interview.
Simply swinging your legs doesn’t seem to untie the knot. Neither does stomping your foot. But the combined motions result in a neatly untied shoe. But why? Well, because when you’re running, your foot is hitting the ground at seven times the force of gravity.
This impact, which is not insignificant, gets transferred to the knot of your shoelaces. The knot stretches and relaxes in response to the exertion of force. This causes it to loosen. And as your leg swings back and forth with the motion of movement, an inertial force is applied to the free ends of the laces.Photo by lazha