Why do your shoelaces come untied? Science to the rescue!

Doing some useful research for once, instead of following the latest moonbat craziness down its joint and several rabbit-holes, the University of California at Berkeley has discovered how and why your shoelaces come untied by themselves.

The answer, the study suggests, is that a double whammy of stomping and whipping forces acts like an invisible hand, loosening the knot and then tugging on the free ends of your laces until the whole thing unravels.

The study is more than an example of science answering a seemingly obvious question. A better understanding of knot mechanics is needed for sharper insight into how knotted structures fail under a variety of forces. Using a slow-motion camera and a series of experiments, the study shows that shoelace knot failure happens in a matter of seconds, triggered by a complex interaction of forces.

“When you talk about knotted structures, if you can start to understand the shoelace, then you can apply it to other things, like DNA or microstructures, that fail under dynamic forces,” said Christopher Daily-Diamond, study co-author and a graduate student at Berkeley. “This is the first step toward understanding why certain knots are better than others, which no one has really done.”

. . .

The researchers found that a shoelace knot unties like this: When running, your foot strikes the ground at seven times the force of gravity. The knot stretches and then relaxes in response to that force. As the knot loosens, the swinging leg applies an inertial force on the free ends of the laces, which rapidly leads to a failure of the knot in as few as two strides after inertia acts on the laces.

. . .

“The interesting thing about this mechanism is that your laces can be fine for a really long time, and it’s not until you get one little bit of motion to cause loosening that starts this avalanche effect leading to knot failure,” Gregg said.

There’s more at the link, including lots of explanatory diagrams.  Here’s a video clip from UC Berkeley illustrating the process.

Well, at least we now know why it happens . . . but I still want to know how to stop it happening!



  1. Some laces stay laced better than others; I think the type of material determines how well the knot resists these forces. I have used paracord as shoe laces and it comes untied more often than any purpose made laces I have tried.

  2. Very easy to stop them coming undone. Just run a nail file or emery board over the laces a couple of times. This lifts enough fibers to provide the grip needed.

  3. I'm more interested to know how three cables laid separately and lying motionless in a drawer can, in a matter of weeks, become a hopelessly entangled ball.

  4. Waxed shoe laces seem to become undone less than normal. I've noticed the military boot laces seem to become undone pretty quickly if not pulled TIGHTLY or double knotted.

    I agree – pretty annoying, especially when outside conditions aren't really good for placing knee on ground and nothing to sit on.

  5. I was recently taught the same knot style as Joe Allen posted (which I believe is the same as the two loop knot mentioned further up). They ought to teach it to kids instead of the standard knot. It pulls free just as easily as the regular knot, but I've NEVER had it unknot itself, even on shoelaces that'll consistently untie with the regular knot!

  6. My shoes rarely come untied (maybe once a year?) using the standard shoelace knot. My wife uses the two loop knot and rarely has an issue.

  7. I've noticed my shoelaces coming untied more frequently in the last few years and I think it can directly linked to global warming.

  8. OK, I'll state the obvious — aside from the creepy monkey-toe shoes in the video this study is another colossal waste of time, effort and (probably) tax dollars! I'll retract my statement when scientists cure cancer or some other real break-thru claiming that this shoelace study was key in their research efforts! Are millenials so dense that they need to "research" this when my 5-year old knows to double-knot his shoelaces to keep them from getting undone…

  9. Well, tying a square knot (with loops) as opposed to the more common granny knot works wonders.

    If you want far more security, then you can tie a surgeon's knot. This entails an extra half-knot, at the start for snugness and/or an extra half-knot on the finish is for more secure from coming undone.

    What's a half-knot just another turn around the other end. You start every shoe tying with a half knot then tie the other half with loops. Where most go wrong is for a square knot, the second half each running part (end) needs to lay alongside its standing part (coming from the eyelet). A granny crosses this up and is a worthless knot, although properly adjusted makes the thief knot used by cooks to reveal when the seamen had been in the stores, as it seamen must take focused effort not to tie a square knot revealing themselves.

  10. The Two Loop Knot above makes tying a square (reef) knot with loops easier. It's certainly better than a granny knot, which my wife unfailingly ties. However, I'd suggest Ian's Secure Knot (https://www.fieggen.com/shoelace/secureknot.htm). It's related to the surgeon's knot that JK Brown mentions, but in reverse. A surgeon's knot has an extra turn at the beginning of the knot, allowing the material underneath to expand, like as a wound heals. Putting the extra turn at the top instead helps keep the laces fixed. Ian's secure knot is an easy way to get that.

    The extra turn is much better than 'double tying' a knot. The double knot is just another overhand knot. It's incomplete, lacks the symmetry of a square knot, and is prone to coming undone. Furthermore, the double knot cannot be untied by just pulling an end, where Ian't secure knot can. I'd been using the extra turn for years when I came across Ian's method for getting there. It's fast and easy. You still have to mind that it's square, not granny.

    With this knot, I don't even have trouble with paracord laces. I will say that with boots having lace hooks at the top I actually wrap the laces around the top hook before the second from the top. This puts the knot securely below the tongue. I find it more comfortable and secure.

  11. Look at how your loops lie when you're done. If they lay across, you're probably doing it right and there is another reason for them coming untied. If they are laying at a 90 degree(ish) angle to the laces you're doing the bow equivalent to a granny knot. It's hard to re-learn the second half…but if you do the first part of the knot the opposite direction but continue the second half the way you always do, the loops lay across and the knot works much better. This has helped people who have apparently been mis-tying their shoes for more than 50 years…

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