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Comment by BuildTheRobots | Hacker News Reader

HowKnot2 have been making empirical testing videos on climbing knots and gear which have proved fascinating and often unintuitive.

If you'd like to see a break-strength test comparing single, double and triple fisherman’s knots, you might enjoy: https://www.youtube.com/watch?v=5CAjUi47QMY

For reference, a 100kg climber is unlikely to be able to cause more than 14kn of force on a dynamic rope, (in reality, significantly less,) even if they go out of their way to find the worst case fall-scenario. Most belay loops are rated at 15kn, human bodies start breaking at 8-12kn and HowKnot2 says that a double-figure-8 (the standard rope<->harness knot) all break at around 14kn https://www.youtube.com/watch?v=g4CVFRE0pRg&t=500s

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Do you by chance mean 5kn, not 14kn? I believe thats the threshold of injury. I believe > 8kn is pretty much certain death, but I don't have a direct source.

Actual tests:

* https://web.archive.org/web/20250712222155/https://www.howno...

* https://web.archive.org/web/20240125125133/https://www.howno...

The anchor experiences greater force in a fall than the climber.

Ah I see now, "force experienced by rope" not "force experienced by climber" :)

The double-figure-8 is pretty rare in climbing, it's the regular figure-8 loop that's used. Sometimes called a "figure-8 follow-through" to describe the tying method. The "double-figure-8" has two loops, it's not at all commonly used in climbing. Mostly just for some improvised rescue situations as part of an improvised harness to replace a damaged harness's leg loops.

yup, it's also great for fixing and equalizing a rope to a sport anchor for top rope soloing, etc. https://www.alpinesavvy.com/blog/fixing-a-rope-two-knots-to-.... Super easy to adjust/equalize.

Yep, you're totally right. I had double and triple on the brain from the Fisherman's; standard climbing knot is but a simple figure-8.

> a double-figure-8 (the standard rope<->harness knot) will break at around 14kn

My understanding (based on some training aeons ago) is that the figure 8 knots prevalence for tying in is not due to that strength - but instead because it is easy to check, hard to back through/untie during usage, and strong when mis-tied (ie errors are made and not caught).

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