UKC

Here's an interesting piece of research from Petzl detailing actual force at various points in the system when taking a leader fall:

https://m.petzl.com/US/en/Sport/Forces-at-work-in-a-real-fall

Thanks for that

Worrying on that FF 0.3. The climber was in a standard position to clip the 6th bolt and only missed the ground by what looked to be a good bit under 2m. Given quite a few climbers these days skip the first bolt and stand out a little to 'soften the fall', the leader in such scenarios might be close to decking when clipping 4th to 6th bolts. Clip the first bolt and/or stay close to it as a belayer.

Good to see real experimental data.

FF 0.7 & FF 1 - they have to do the testing half way up the wall because the climber falls past the initial position of the belayer's feet which usually represents the level of whatever the belayer is standing on.

Generally rather than fall past whatever the belayer is standing on you hit it unless you have a convenient void to fall into.

Tie the belayer down for a harder catch, direct belay for upward pull or just do not fall?

Or it's multipitch?

Would be interesting to see the same experiment with a non-assisted braking device (eg ATC) but I doubt Petzl would do that

Correct. It states in the text that they are modelling a multipitch fall. Two reasons they probably don't use either of their non-assisted braking devices (Verso and Reverso) are one, it introduces another variable into the experiment (belayers hand force) and second, in the bigger falls there is a very real chance of dropping the climber.

Yes it says multipitch but more often than not falling to the level of the belayer's feet means you hit the belayer or their ledge (mid route) or the ground (start of route). 

The FF 0.7 is gear at 2m above belayer and climber 1m above gear does not sound like very necky cragging  but it still results a ground fall. I hadn't really expected that without gear popping.

It's well known from DAV studies that you will probably deck if you blow the clip up to the 5th bolt with indoor spacing of bolts.

I'm not sure how much hand strength would play a part as it doesn't take much strength to arrest a fall, but I agree with your second point which would lead to a much smaller pool of volunteers!

If you click through to the next set of results ("Influence of the belay device" at the foot of the page) they do present some results comparing forces when using a Grigri vs a Reverso, at the same fall factors.  No videos of the non-assisted device tests, though, and they do say: "The results are influenced by slippage in the belay device and therefore by the belayer's grip. Variability is thus high".

Well, what do I know!

For the test where the force on the belay gets towards 2kN, I think slippage through the hand is going to become likely. The multiplication factor of the belay device will be in the order of 10, which means a hand force of less than 0.2kN could result in slippage. Measured results for hand force vary between individuals between anything from 0.075 and 0.35 kN. 

Sounds plausible. I can do just under 50 kgf on a dynamometer (=~ 0.5 kN using 10 as a conveniently approximate conversion factor). That's with considerable mental preparation and gritting of teeth, gripping a device that's ergonomically designed to be gripped hard: I can well believe I'd be under half of that having to react in the spur of the moment on a little bit of skinny rope. And I'm a fairly large bloke.

It may be well known from DAV studies but its most certainly not well known by indoor wall users nor is it advertised at walls, along with methods to cut that risk. I've not seen such studies and have always been a bit of a risk analysis nerd.

Interesting. I can confirm that the DAV does teach it in standard courses, surpised it's not more widely known elsewhere.

You always go miles further than the simplistic 2x rope-to-gear assessment would suggest, the little hidden extras often add up to more than the obviously available rope.

I'm not sure what good you're suggesting clipping the first bolt would do, seems to me it'd most likely injure the belayer and potentially release the gri-gri.

jk

Do you have links to any studies on this? I can be quite nerdy about these things

For the same reasons the study we are discussing recommended clipping the first bolt as its key advice on the FF 0.3 test?

"Advice

Systematically clipping the first quickdraw reduces the chance of a ground fall, by limiting belayer displacement."

Maybe I am just missing your sarcasm, but not quite.

The official DAV training handbooks simply say that belayers should be especially careful, especially with the amount of slack in the system, close to the ground.

Surprisingly, this zone of ground fall danger extends up to the fifth bolt (i.e., there have been documented accidents, presumably with a light belayer, lots of slack, and the leader faffing an overhead clip up to that range). Above that the ground fall risk statistically becomes negligible.

The "fifth bolt" merely serves as a rule of thumb to help novice climbers with assessing ground fall danger at standard walls.

CB

Time to get a clip stick to reach the 5th bolt when indoors.

Not necessarily, staying close may not always be a option, e.g. under low roofs or undercut starts, or on blocky ground outdoors. In these cases you have to decide which direction of "belayer displacement" poses the bigger risk. Getting some air time by being pulled up is usually harmless, getting whacked into the wall less so. Since the lower the first bolt, the higher the lateral force, not clipping the first bolt can sometimes be the only way to enable a soft catch.

CB

https://www.infona.pl/resource/bwmeta1.element.springer-2ba10d5d-9d0a-3d26-...

Plus unpublished research by the BMC technical committee which builds on that work.

Fair enough except they don't actually do it in any of the videos, presumably so as not to risk injury to the belayer though in all three falls the belayer apparently stops below the 1st bolt anyway. I've always preferred the extra freedom skipping the first clip gives particularly outdoors where the ability to move for a view our out of the firing line of debris is valuable.

jk

There´s work by the DAV and CAI on this, the DAV use a value of 250N (the mean of theirs) and the CAI 170 (90% population).

The drawbacks with their tests (and the BMC ones) is the grip is measured in an optimal position and not the combination of grip strength and arm strength in a belaying situation, I can grip 450N but can´t stop my hand being sucked into the device in a normal belaying situation (force from above).

It has also been noted by the DAV in drop tests that the participants can briefly hold roughly double they can in a sustained pull, whether this is long enough to stop any particular fall is guesswork

Since this was explicitly covered in Mountain Leader Training's workshops for Climbing Wall Award providers prior to the launch of the CWA/CWLA qualifications nearly a decade ago, IN THEORY every single qualified climbing instructor working indoors the UK should be well aware of this!

However, that of course assumes that all the providers actually do a good job and that instructors don't suffer from any of the normal human failings of information overload, forgetfulness or complacency...

The standard demonstration is to use three people so that the lead climber is also belayed on top rope. You can then easily simulate falls and or fumbled clips and look at the consequences. Unless the belayer is literally touching the wall directly below the first clip and the leader climbs UP to the first few clips (rather than clipping at full stretch) the result is generally the leader decking normally after hitting the belayer and/or the rope.

Recently I've seen some atrocious belaying at wall. However I'm not sure whether I'm more disgusted about the ignorance of the climbers or the lack of action by the climbing wall staff!

On a personal note, at one wall last week I was routinely leaving the first draw preclipped as the routes tended to be hard and bouldery from the first move. Equally, there is the very occasional hard repoint indoors at my local wall where I'll preclip the first two draws rather than risk decking out.

That said, despite all this lack of knowledge and poor practice it is still indoor bouldering that leads to the vast, vast majority of injuries...

I don't think belayers will necessarily apply their maximum force, they will hold the rope with enough force to, in their experience, catch a fall.  The catch is a practiced movement they've done many times, they are expecting it to work with the grip force they normally use, not getting ready to use their maximum possible force.

If the amplification of the belay device can vary significantly according to rope angle, newness and diameter there is a problem because if the conditions align in the worst possible way and the belayer ends up in a situation where the amplification factor is lower than they have experienced previously then the grip force which they expect to work may not be sufficient.  Once the rope starts moving through their hand they've then got a fraction of a second to stop it before it starts moving so fast the reflex action is to let go to avoid being burned.

We are only interested in whether the belayer can apply enough force.

What we can take away from this is that whenever you here that irritating music when you're climbing be very careful

Again I get what you are saying and agree up to a fall clipping the 3rd bolt but was unaware of this DAV training saying this will probably happen if falling when trying to clip the 5th bolt (maybe Jonas means pulling slack up and clipping from well below as I find it hard to believe otherwise). I started a survey thread and most seem to deny this is possible without poor belay practice (in direct contradiction to what Jonas and others have said).

https://www.ukclimbing.com/forums/rocktalk/sport_climbing_safety_informatio...

I was chatting to an experienced and well trained wall worker last weekend and they were saying its a real pain to convince middle aged men with 30+ years of climbing behind them that they really need to brush up on their belay technique.