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There's a dispute in my climbing group whether a "large" eye of the tie-in knot can be considered dangerous. While I don't see a problem with a loop that is about 10 cm across, others argue that the loop should be as tight as possible.

We're climbing indoors and use figure-of-eight or double bowline as tie-in knots.

What could be more dangerous when using a "large" loop?

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In case of the double bowline it gets undone more easily than with a small eye, as it can move more.

For the figure of eight the only factor I can think of is the same as with a too long loose end: If you clip in a hurry and the express is rather low, it can happen that you clip the wrong strand. That might seem unlikely, but given enough time/repetitions, almost anything can happen. With the loose end it means a long fall, with the eye it's worse, as it will block you, which can easily lead to a fall, which then gets arrested almost statically by the express. That's ~30cm fall, which is already quite bad and potentially leading to injury.

And outside it also falls on the general rule of keep your gear and setup neat and tidy. Anything loose is anything from an annoyance to a real danger.

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    @TobySpeight I added some info about that, though I think that's unnecessary detail: Having just a small loop of rope (two strands will break -> twice the breaking) as a dynamic element, I'd just consider that a static arrest. It will be a bit better than fully static, but still not comparable to what you're used to with dynamically arrested climbing falls. – imsodin Jun 17 at 10:44
  • I disagree with the fall factor maths here. For a 30cm fall the stretch in harness + climber-before-anything-breaks is significant. I think in practice this would be an insignificant fall. I'll test the theory this evening and post back. – ANone Jun 18 at 8:08
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    @ANone Please don't! I can attest that falling 10cm into a daisy chain can break the daisy chain loops and give you back aches for roughly a month (source: friend doing that while aiding). The "dynamic loop" wasn't there, but the daisy chain also acted as a "damper". And fall factor has a clear definition and "stretch in harness + climber" isn't part of it. I still rolled that back as I think fall factor isn't relevant here, it's designed to measure the severity of a regular fall, while here we have a very irregular situation - it might be (probably is) an ill suited instrument here. – imsodin Jun 18 at 9:24
  • I think the newer version is better. Definitions aside, I agree this is an irregular circumstance and the number doesn't apply. (In fact, if i followed correctly, using the original maths: the smaller the eye the larger the fall factor!). I'll take it by increments, but I'm curious. I have a hard time believing that's a bad fall. – ANone Jun 18 at 10:17
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    Yes, a smaller eye gives a higher fall factor (because the amount of dynamic, force-absorbing rope falls by a much greater proportion than the fall length - which is dominated by the sling or quickdraw). The important point is that a small eye makes this mistake very unlikely. – Toby Speight Jun 19 at 13:38
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Indoors, with the loop tied directly into the harness, short of taking the mickey, the worst I can think of is that you might get hit in the face by the knot.

The knot itself is just as safe and 10cm is not silly. I'd be perfectly happy from a safety point of view climbing on a 10cm figure-of-8 or double-bowline. Or for that matter a 20cm loop, though I'd prefer not to for non-safety reasons.

It's at least possible it leads to another mistake. Generally anything sloppy is less obviously when it's wrong. That could be the setup itself or something looking like: the rope looking like the slack is all gone, but there is still slack in the knot. However, that is a really subjective line of thinking and if you're relying on something like that to be safe, you have other problems.

You also slightly lose the compliance in the rope but the extent is tiny between a 5cm and 10cm eye.

I think this is a hang-up from outdoors where things getting snagged/taffled etc is more likely and more dangerous.

All that said, why wouldn't you tie a neat loop?

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  • What you wrote only applies to top rope climbing. A large loop is just as dangerous when leading indoors as it is outdoors. See imsodin's answer. – Qudit Jun 18 at 0:36
  • @Qudit: It certainly wasn't aimed solely at top roping. I had leading in mind. I doubt there would be many worried about loop size for top-roping. – ANone Jun 18 at 8:00
  • Your answer doesn't address the issue of accidentally clipping the loop. Climbing indoors does not reduce the risk of this. – Qudit Jun 18 at 8:35
  • @Qudit, see the comments for that answer. I disagree with the logic. That said, I'll think if i can word an addition to cover that case. – ANone Jun 18 at 10:19
  • Regardless of exactly how hard the fall would be, falling on a short length of rope is clearly undesirable. Moreover, such a fall could crossload the tie in knot. Figure eights and many of the variants of the bowline do not withstand crossloading well. There's simply no good reason to use a large loop and many reasons to avoid doing so. – Qudit Jun 18 at 17:24
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If you fall, and it gets caught on something on the way down, you're gonna have a bad time.

It's pretty unlikely that it will catch on something (though here's a similar (horrible) story), but the sudden stop would cause a lot of damage. I think this would be worse than a factor 2 fall, because you've already been accelerating and then are being stopped by a very short piece of rope?

Also, if it's a really huge loop and you're lead climbing, you could clip the loop by accident, which would essentially be a factor 2 fall if you kept climbing above it and then fell when it went taut?

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    It could be more than a factor 2 fall. Since it's a very short length of dynamic rope you also have to take the length of the static quickdraw or runner into account. – Qudit Jun 20 at 20:06

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