Against safety

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Most climbing at climbing gyms is done on top-rope: this means that the climber is supported by a rope that runs through an anchor at the top of the wall. The person holding the other end of the rope (the belayer) stands at the bottom of the wall and takes in the slack in the rope as the climber ascends. I suppose it's theoretically possible to belay just by holding the rope in your hands, but it's prohibitively difficult: most people can't easily apply 150+ pounds (600+ Newtons) of force to a rope continuously, and if the climber is falling, it's much harder to stop them. Instead, you use a belay device: a gizmo that attaches to the belayer's harness and lets the belayer apply friction to the rope.

Most modern belay devices are of the "tube" variety, such as the ATC, shown below.

The way that an ATC works is that the climber's rope goes through both the ATC, which is just a metal tube, and a carabiner attached to the climber's harness. In order for the climber's rope to pay out, it has to feed through the carabiner and the ATC. To stop the rope from feeding, the belayer pulls on the free end of the rope with his brake hand, which pulls the rope tight against the edge of the ATC where friction stops it. Effectively, then, the climber is hanging from the belayer's harness (remember, the rope is going through an anchor above the climber), with the belay device coupling the rope to the carabiner.

The key point here is that an ATC is passive; if you ever let go of the free end of the rope, it will feed freely and if the climber is weighting the rope, they will fall, potentially to their death. This makes technique important. In particular, as the climber ascends you need to take out slack in the rope by pulling on the free end. However, eventually your arm will be fully extended and you need to move your brake hand up the rope. It's important to do this without letting go, because if the climber falls during that period there's nothing to stop them. The standard technique for this is to take your other hand and grab the rope below your brake hand and then slide it up, so there is always a hand arresting the rope. There are other techniques, but they are less safe.

You can also get active belay devices which autolock if tension is suddenly applied. The most popular of these is probably the Petzl Grigri. The Grigri has two main advantages for toproping: first, if you're not paying attention and the climber falls, the grigri will autolock and catch them [there is a lever you pull to unlock the device so the climber can descend.] Second, if the climber needs to hang for a while, you don't need to apply tension to the free end of the rope to keep it from feeding through as you would with an ATC. [Lead climbing, where the climber pulls the rope up with them and sets their own anchors, is more complicated. Here, I'm just talking about toproping. Grigris are popular in part because the autolock seems safer. Planet Granite, where I climb, has Grigris fixed to the line and won't even let you toprope with an ATC. PG also has another safety feature: the anchors at the top of the wall are large diameter (4-6") metal pipes with the rope wrapped around the pipe twice.. The effect is that when tension is applied to the rope it cinches around the pipe, creating a lot of friction and thus arresting the climber's fall (though not necessarily to the point where they couldn't get hurt) even if the belayer does nothing. [Technical note: the instructors at PG regularly tell students that the double wrap halves the climber's effective weight, but this misunderstands the basic physics. There's no movable pulley; it's purely a friction effect.]

I'm not sure that either of these are really good ideas for a climbing gym. While I suspect that Grigris really are safer for topropoing if that's all you use, they don't give you any feedback for bad technique because the climber won't fall even if you totally fail to lock off the device yourself. It's quite common to see people using the "pinch" technique where they pull the free end of the rope up to the end going towards the climber, pinch them both together with their free hand [which is usually pulling down on the rope to feed it through the aforementioned high friction anchors], and then move their brake hand up towards the belay device. This is OK with a Grigri, but because the ATC's friction depends on the rope being pulled against the edge, doesn't provide acceptable braking with an ATC. Yesterday, I heard an instructor at PG tell a belay class that if they lost control of the climber's descent (e.g., you're pulling the lever and having trouble braking with the brake hand) you can just let go and the Grigri will autolock. While this is true with a Grigri (though you're not supposed to rely on it), it would be disastrous if you were using an ATC. So, my concern here is that always using a Grigri encourages bad habits that could get you into real trouble if you ever used an ATC, either because you were lead belaying or were at a gym that had ATCs instead of Grigris. Perhaps what would be best would be if some small fraction of the ropes at PG were set up without belay devices and they encouraged you to use ATCs on those so you would learn how.

The pipe thing is even worse. Lots of gyms have anchors with much lower friction (e.g., carabiners at the top). If you're used to the slow descent provided by the pipe, you could drop your climber way too fast even if you were using a Grigri. Even if you don't ever climb at another gym, the variation in anchor friction is quite high with the anchor getting slower as the rope ages. I've seen anchors where the climber actually had to bounce to feed the rope through and descend and ones where there was barely more friction than a carabiner. So, this is a problem even if you only climb at the same gym. Again, I know why they do it: it seems safer, but it teaches bad habits which could get you, or rather the person at the other end of the rope, seriously hurt.

2 Comments

Re: ATC vs Grigri: If you really want someone to learn to belay properly, yes, having them use an auto-locking device is counterproductive. But let's look at the gym's incentives here. First, I suspect they get a break on their insurance by requiring use of Grigris. This was the case at the gym I climbed at in college. (We couldn't even use ATCs for lead belaying. What a pain.) Second, teaching someone to belay properly with an ATC is hard, and a lot of people require babysitting and remedial instruction afterwards. This costs employee time, which costs money. Supposing that PG doesn't really care about teaching good belaying, just trying not to get sued after somebody decks, using Grigris is the better proposition.

Re: anchor systems: We have the double-wrapped pipe thing at my gym. While I'm not sure I can back this up with physics, it sure seems like the extra rope drag makes it easier for me to belay much heavier people without getting air time. ISTR PG having ground anchors, though, which are the better solution to that problem.

"it seems safer, but it teaches bad habits which could get you...seriously hurt."

Doesn't all rock climbing safety equipment, by definition, fit this description?

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