Shoelaces often come untied while we’re walking — it’s happened to the best of us many times. We can pretty much all agree that it’s annoying, but one group of people seems to find it so puzzling, they actually conducted a study on it.
In the most recent issue of Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, the researchers looked into “the roles of impact and inertia in the failure of a shoelace knot.” So, what exactly does this mean?
The researchers found out how a series of events leads to the untying of a shoelace, including repeated impact of a shoe on the ground and the whipping motion of the laces. The group observed footage of a runner on a treadmill wearing shoes that had been knotted using a “weak knot.” They noticed that there was little change in the knot for many strides but once some untying began, the speed of untying was “remarkable.” Unsurprisingly, they also found out that a weak knot fails at a higher rate than a strong knot.
The strong knot is essentially a square knot, and the weak one is what is known as a “granny” knot. In shoe-tying terms, the weak knot is the “bunny ears” knot, which is how many people learn to tie their laces as children. Despite the fact that it’s still a common way to learn, science is saying it’s time to change things up.