UKH

If anyone has measured, how far have you gone when you took a trad fall from above the gear where the belayer was competent and giving you a "stop now!" catch rather than a "soft catch"?

I'm interested to know what sort of best-case scenario you might have on a sketchy lead with an alert belayer if the fall is from 1m, 2m, 3m, 4m, 5m and 6m above gear?

I know that with a little slack in the system and belayer reaction time, a fall from 1m up could easily become a 4m fall in total even in ideal circumstances. Intuitively I imagine that the 1:4 ratio will fall as the fall becomes bigger but I don't know by how much and a couldn't find much with a cursory Google.

Hard to say due to so many variables, the main one being weight difference I imaging. I know I'm in for a longer fall but softer catch if being belayed by my 5' 4" GF. For leads that are run out and droppable I have at times waited for a heavier belayer, or asked a friend to hold my GF down!

Not to mention slack in the rope, and rope stretch. They make a difference (they certainly did on my 80-foot peel on a vertical part of Main Wall at Avon with an alert belayer (thanks Frank)]

Yeah, I'm huge so I'd always be tying the person down in a situation like this. If I so much as sat on the gear with a 5'4" person belaying they'd fly up till something stopped them (or the ground stopped me)!

Also the reason I'm asking the question is to do with a specific new route I was looking at and it's multipitch, so the belayer would be fixed.

Oh, that sounds promising! How far above the gear? How far did you go? What stopped you?

Fat belayer, good hands, and a reasonably dynamic rope for the win... Or just follow the maxim of "The leader must not fall' and persuade gravity of the same. 

I was a long way above the last gear - which ripped. The next gear down, a tiny pathetic nut on a sling, held me - I don't know how far above that gear I was. My total fall was 80 feet, ending up JUST above my belayer on a ledge (sorry that wasn't clear from my first post)

It was over in a flash and wasn't scary at all, just thanks Frank and thanks to the tiny nut

I can't even persuade gravity to give me a temporary respite when the shampoo bottle slips out of my hand in the shower!

There are plenty of "must not fall" times but I'm looking for information that is a bit different - this is the question of how far you can run it out on ground which is just too hard for you personally to do it in do-not-fall mode.

That sounds perfectly horrendous, glad to hear you got away with it!

Thanks. It wasn't too bad, I didn't hit anything on the way down so no injuries at all. Just a bit shaken up maybe - that was my last climb for that day, back to it next day

There is some good info here and the videos show the distance The leader falls in a controlled environment.

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

hope it helps

This, my friend, is precisely why soap evolved ropes. 

Thanks. That's helpful, it's just a shame that they didn't do any fall distance measurement beyond the initial setup, they were only interested in forces. It is possible to eyeball how far the climber goes though.

Depends how far off the ground you are. If it’s only a few metres, the belayer can ensure there is minimal slack, which would help.

This isn’t remotely scientific but I generally think that if there is gear two thirds of the way from the ground to your waist, you should be ok. Less than that gets dicey.

A less stretchy rope is sensible but has to be weighed against the risk of the gear failing under a higher impact force.  

Have a look at videos of Master’s Edge. It’s a straight up line, so a good illustration. 

Ok. We're all dying to know - I am at least - which route was it? Don't think I can even start to guess; there are probably many possibilities!

It was Krapp's Last Tape (E3 5b). Not the best route to fall off. I went off-route in the upper part, trying to go straight up to the belay instead of moving down and right (for some reason - lost). Finally I couldn't move up or down and my fingers eventually gave way

Hmm, that's interesting and because you still have your legs extending below the knot it would actually equate to a bit less than a fall of 3x distance above gear... Or are you thinking that if only your legs hit the ground on rope stretch then you will get away with it?

Thanks. I will, shame I can't abseil down it and do some measuring! (It's a bit too far away)

That is a horrible place to fall.

Well done Frank the belayer! 

Depends how much you want to be short-roped. 

I've taken an 80 footer (at least) too and it seemed to go on forever. 

Yeah.

On big falls my first thought is "why is the crag moving", then the realisation that its me that's moving .

Not exact, apparently its hyper complicated, but try proportioning the forces to the extension and force at breaking point. That might give you the percentage stretch and thus the finish point of the leader.

I know what you mean - I've also taken a 90-foot fall entirely through space. I remember the world spinning round and round and flashing past... I went head-over-heels... I had plenty of time to think... strangely I wasn't scared but was just thinking "Oh well this is it here we go then, wonder what's going to happen next....."

It's always much further than you think it will be/should have been.

I'm afraid I didn't follow that. Can you try explaining again? Sorry.

Yeah, I know from my own falls but how much is "much further"? That's the real question. If you are 12m above a ledge and the gear is 4m below your waist, do you hit the ledge? And if so, how badly?!

Soft catches aren't neccessrilay bad! Just need to pick the right situation. 

Try setting it up on a crag.

Put your runners in and hanging on an abseil rope, replicate the fall with your  climbing ropes until your weight is on the climbing rope. You will then have taken all the slack out of the system and stretched the rope to body weight. In the real fall more stretch in the rope due to your body deaccelleration will obviously result but at least you know the starting point for your assessment.

I know. I just wasn't interested in them for this thread because I was wondering about hard limits.

Thanks, that does sound like a good place to start... I worry that it might lull me into a false sense of security though because that extra bit of rope stretch might well be the bit that matters.

It probably will be but at least from the body weight point you will be deaccellerating .

If its a good runner you might be able to organise a running belayer.

This YouTube video of a fall from the top of Masters Edge should give you a data point:

youtube.com/watch?v=oSDGuR3oIm8&

How far will a lead fall be, considering all variables? I think the only answer to this question that would consistently be accurate is: Further than you think. 

I unexpectedly came off the crux of Good Friday Climb at Stanage with gear at knee level which held and nearly kicked the belayer in the head.

I think that should be modified to 'A f*** of a lot further than you think'.  It always surprises me.   However, it doesn't always - like last Sunday when when I had one of those graceful teeter-off-out-of-balance moments whose slow motion allowed a grab at a peg as it went past and a consequent total lack of drama.

I recall watching someone climbing stylishly, but with 'sub-optimal gear', gear not in a straight line, single rope, masses of slack and a belayer some way back.  I had a good vantage point on a stance up and left, did a quick think, decided 'sport climber - new to trad', and spoke up.  I said something like, 'Did you know that you'll probably hit the ground if you fall from there with all that slack?'  They said they 'didn't like slamming' and 'preferred lots of slack'.  One can only try.  Fortunately, my vision of the future was not tested.

Well it’s a rough guide with no real science behind it. Depends how relatively heavy the belayer is as well. 

Depends where the belayer is. If they're on the ledge in question and belaying with minimal slack in the system, should be OK I would have thought. If they're 20m below the ledge then you'll probably hit it.

Thanks. That's a good data point. The belayer definitely gets an arm of slack in and I don't think moving back made any real difference to rope lengths. With my trusty ruler it looks like he was 5.5 off the ground with gear at 3.5 and the rope goes tight at 1.5 and it looks like he might have stopped about 0.5 off the ground. So if you accepted a hard catch with the belayer taking in an armful, you could definitely stretch that 3:1 fall ratio out a little more. Hmmm....

They'd be on the ledge.

A long time ago I watched a friend climb on a single rope, clip zigzag gear, fall off, rip enough out and crater. Fortunately he got away with just being winded. If they are not interested in listening to sensible advice, I hope the guys you were watching don't get injured when their practical lesson arrives.

Thanks, very good videos.  Interesting that even in a factor 1 fall the forces on climber and belayer wern't too bad, better than I expected.   On teh other hand the distance fallen in the facrot 0.3 was much more than I expected. 

then add the distance your belayer will have gone up the wall (or forwards!?). 

Rope stretch (10% give or take?), slack taking up, belayer going up. Even with the gear by your waist/legs you still go a few metres when youre 15m up. All depends, as has been said its always further than you think. I went about 5-6m on tangerine dream when I had kit by my feet (at worst) and no slack, I was surprised, the rope went tight and I kept going, skinny halfs, no friction from runners and a light belayer. 

Generally speaking, the belayer should be tied down with at least one piece of gear that will take an upward pull.

I'd say in general falls seem to be around 3x length of rope above runner, but options to reduce substantially towards 1x or maybe bit less with planning e.g. see falls off Gaia, End of affair etc. where v low directional runners, fat single rope and multiple/speedy/jumping belayer help reduce slack - albeit will increase in forces on top runner and climber plus I'd imagine takes some (lots?) of practice to get reliably right...     

Do you mean 2x? Because 1x would be where the leader only falls to the last piece of gear and no further.

I think for my purposes I have to rule out sacrificial or running belayers because the former would be just plain nasty and the latter impossible. I've watched the former recently and it had a bit of an effect but I think you are right when you say you would need to really train at it to make a big difference.

Belayer will be fixed for my purposes.

Those are some good points, I guess using two full ropes instead of halfs would be a good plan. Probably don't want to try to address the runner friction as that would make leading harder.

To the downvoter: it is standard practice in trad climbing to have an least one belay piece, out of four say, arranged to take an upward pull. The only common exception is when the belayer is on the ground (e.g., when top-roping or sport-climbing) and there is no risk that he/she would be slammed upwards and into the rock. 

A dynamic belay is provided by the slippage of the rope through the belay device, and only a small amount of lifting of the belayer is useful. More than about 20 cm of uplift increases the fall distance and does not decrease peak force. 

If one wants to minimize the fall distance then perhaps sometimes one should have a different belayer for each rope. I seem to remember that someone, probably Jim Titt, had tested various tube devices and found that if one rope remained stationary in the device when the fall was held on the other rope as happens when runners are widely spaced then the braking power exerted by the hand was substantially reduced. Perhaps anchoring for upward pulls and a grigri for each belayer would be best, which would eliminate any rope slippage   .  Proviso: my technical knowledge is poor.

Don't know if you are aware but you can hide all the like/dislikes in your user settings. It makes UKC feel a lot more relaxed (for me at least). In any event, I wouldn't bother wasting typing time on someone who just dislikes without giving a reason by replying.

(And I'd agree that a belay should normally be multidirectional with the exact way you rig it being based on lots of things like surrounding rock, gear on the next pitch, weight of belayer, etc etc)

Hmm. That's an interesting bit of knowledge. I've seen 2 or 3 belayers before, I think sometimes off to the side to prevent the leader from swinging into something when they fall.

It also presents the interesting possibility of having two ropes going through different gear but at about the same height (the last gear cluster), where each rope is optimally belayed _and_ the counterweight of 2 belayers would help greatly with the short hard catch while not being so unpleasant from the belayer pov (let's face it, it was the leader who mainly wanted to do the route in the first place!)

Good luck with your project

Interestingly. if my memory and interpretation are correct, in the same set of tests if the fall load was shared between two ropes in the tube device then the braking force was greater than if only one rope (same diam) was used. However this was not twice the braking force of one rope. Thus another advantage of two belayers would be that double the braking force would be obtained in this case and fall distance would be decreased.

As I expect you appreciate, you've not given us some vital pieces of information: how much rope is out (ie where is your belayer - on the ledge or some way below the ledge); is your belayer tied down or able to be lifted; how much do you and your belayer weigh; and what are the dynamic properties of your rope.

In all situations you will fall 4m plus the slack in the rope (probably approx 0.5m with a good belayer) before deceleration starts. So your waist will then be 3.5m above the ledge and your feet approx 2.5m above the ledge. You will have generated "mgh" joules of energy (you can calculate if you know "m") which must then be absorbed by the system - ie stretch in the rope and/or lifting your belayer, and any friction of rope against the runner krab(s) and the rock.

The percentage extension in the rope will vary according to the energy absorbed by the rope (it may be proportional to this energy - others with greater knowledge can confirm) and the rope's dynamic properties. The energy absorbed by lifting your belayer (if not tied down) will depend on your relative weights. 

Optimally, if your belayer is standing on the ledge and tied down you will have 11.5 metres of rope out (assuming 0.5m of slack). So a percentage extension in the rope of 2.5 / 11.5 (21.7%) will put your feet on the ledge (softly). My guess is you would be OK. In every other circumstance (belayer not tied down, belayer some distance below the ledge) I think you are going to hit the ledge, probably quite hard.

Martin

Thanks. I was initially looking for some kind of general rule for fall distance but then switched to the specific example that had motivated me to ask but I think I sprinkled the details around a bit. It's a multipitch so the belayer will be fixed and they are belaying from the ledge, so no extra rope in the system.

The line in question is going to join a couple of others on the long term projects list because it's far too hard to attempt without a load of indoor training to get stronger. So that should give me plenty of time to find a couple of belayers who might be willing to do one role each as Oldie suggested (I'm like 100kg+ so the experience of anyone belaying on their own would likely be nasty).

Thanks 🙂

Just spotted an error in my post above. You will of course fall 8m plus the rope slack, not 4m, before the belay kicks in. The rest is, I think, correct. Your feet will still be 2.5m above the ledge when deceleration starts. But an 8m free fall is a long way! If your belayer is on the ledge you have only 11.5m of rope out and this is close to a Factor 1 fall. You'd want to be certain of not hitting anything else on the way down I think. You'd need to be absolutely certain the runner will hold. And you would need to tie the belayer down - otherwise you will hit the ledge quite hard, passing your belayer heading upwards as you do so. Most climbers I see (self included) are happy with anchors above the belayer on stances on multi-pitch routes, especially if they are multi-directional. But I don't think that would work here. 

Also any advice from me needs to be in the context that I've taken (touch wood) only around ten substantial leader falls in 50 years of climbing. I think we may be different sorts of climber!

Martin

Fun thought experiment you have going on here. I'll bite too.

I assume your belayer will be tethered to the anchor similarly as in the Petzl fall factor 0.7 example where the belayer is yanked approx. 1 m directly up before the anchor stops him and the climber falls below him and the 'ledge'. Actually, given your free fall and rope in play, your fall factor will be similar to that experiment. And since the impact forces are proportional to the fall factor, your impact forces will be similar to those in the Petzl example. But as your free fall is longer, it will have more energy, and as your rope in play is 4 times longer, your rope stretch will also be 4 times longer. All in all, I'd say:

You will hit the ledge hard!

Silly speculation - could belayer (v well attached) *nudge* a haul bag full of rocks clipped (not knotted) to the live rope off said ledge at appropriate moment to take in some slack as you fall? [prob collecting Darwin award in process...]. Alternatively tried and trusted method of top-roping until pretty sure you won't fall off?  

Interesting idea. Would really need it to be clipped above the first (bomber) runner. But more to the point, with both climber and haul bag free hanging, what then...?

I had been thinking along similar (theoretical ) lines but with a jumping third person clipped in between the first and second( last) runner to take in the slack.

All so dependant on good gear that I dismissed suggesting it.

If you did that, I'd hope it didn't hit a party below!

Thanks. The runner is a cluster of gear, 5 or 6 pieces probably and some are going to be absolutely bomb proof.

Oh, that's just a technical problem, easily solved with an ab rope or something hanging off to the side that the belayer can flick across to the leader and then a bunch of faff getting the whole system reset.

Hmm. That's not very encouraging!

I would say a few things though: Firstly, the slack in the system is probably proportionally about 4 times as great in the petzl example because it's the same absolute quantity whether you are 2m up or 12m up.

Secondly, the 1m that the belayer goes up in the petzl fall will be essentially 0m if the belayer is tied down, so that puts the leader 1m higher up in the example fall.

I will admit though that even if you take both of these things into account, multiplying at petzl example up to 4m and 12m does make it look like pretty bad news.

Haha, honestly, I think that knowing my belayer had a hairtrigger bag of rocks would just terrify me on the lead. I can mull it over a bit but I'm minded that I've never seen anything like that in videos of people doing hard trad and those videos have a fair number of inventive insane solutions!

The latter is a given. The wall is vertical pretty much so the fall would be nasty anyway. Thing is, I'm not sure I could ever get certain enough of the moves to try leading with a don't fall off mentality. I suppose I'll have to try and get strong and see how it goes.

These figures from Jim Titt  may be the tests I was thinking of:

ATC XP/9mm rope. One of a pair loaded 193kg, single strand 242kg, loaded equally 293kg.
Reverso³/9mm rope. One of a pair loaded 148kg, single strand 194g, loaded equally 240kg.

UKC Forums - Friction abseil device for skinny ropes 2015

I think it was also pointed out that double krabs at device would increase friction.

Hi there.  I hope you're still following the thread. Partly out of personal interest, and also because I was worried I had offered advice above that might lead to an accident, I did the maths (I'm retired with some spare time). The conclusion is that you will very probably hit the ledge!

As above, I assumed that your belayer is firmly tied down, his/her belay plate is 1m above the ledge, he/she is belaying with 0.5m of slack and lets no further slack through the plate when you fall. You will therefore have 11.5m of rope in play and will fall 8.5m (4m to the protection, 4m past, plus 0.5m slack) before the rope goes tight. Your waist attachment will then be 3.5m above the ledge and your feet 2.5m above the ledge. I've assumed it's a free fall.

For the rope parameters I chose a Petzl Contact single rope with max impact force 8.4kN and dynamic elongation 35%. Both figures are measured in the standard EN test. I assumed that the rope obeys Hooke's Law and force is proportional to elongation (which may not be correct). I also assumed no friction at the runner (which is clearly untrue). Friction at the runner should reduce the distance fallen I think, but probably not by enough to give you an acceptable margin of safety. 

I did the maths empirically on a spreadsheet using 1/1000 second intervals. I think it could alternatively be done analytically by integration or using adapted simple harmonic motion equations. 

The results are as follows:

At time zero (when the rope goes tight) you will be travelling at 12.9m/s. You will continue to accelerate for a further 0.037s before the rope tension balances gravity. You will then be travelling at 13.1m/s. After 0.208s your feet will hit the ledge. You will still be travelling at 9.7m/s (in excess of 20mph - ouch). If you've inverted, this will be your head that hits the ledge rather than your feet - mega ouch!

Interestingly though, your waist will never hit the ledge. After 0.38s your waist will still be 15cm off the ledge and you will have been slowed to zero velocity prior to bouncing back up.

The rope will then be under maximum tension of approx 7kN. Disallowing friction at the runner, you need to double that for the max force on the gear. So that's 14kN - just beyond the guaranteed strength of most gear. As others have pointed out, this is a serious fall - factor 0.74.

There are a great many potential errors in my maths, which others may point out, and false assumptions (I know you've said you will use double ropes) but on this basis I definitely couldn't recommend going ahead. 

Interestingly when I replaced your weight (100kg) with mine (65kg) my feet still hit the ledge but at only 4m/s. I was slowed to zero velocity with my waist 39cm off the ledge and the max. tension in the rope only 5.4kN. I still don't think I'd go for it though!

I can forward my spreadsheet if you're interested.

Martin

Yeah, that would be great, thanks!

I'm still reading

I had a bit of a look today and it looks like a better option on the route would be gear on the other side. It would be 5m down and 16m of fall before rock contact but with a steep slab rather than a ledge so you could probably get away with hitting a lot faster and continuing down. That would also give the belayer a little more time to take in rope. I'm thinking that two belayers each with a full rope would be the way to go.

I think the friction from the gear should help to slow me faster though perhaps not make a big difference to how far I fell.

That force on the gear is a bit worrying... I feel like something else would give before it got that high - maybe rope slipping through the belay device a bit or something.

Non-technical person here following discussion with interest. If one used a second rope (preferably with separate belayers) then that would arrest earlier, though presumably one would need more than one runner at about the same point for more strength. There would be a greater arresting impact on the leader, but probably preferable to an impact on the ledge. 

In connection with a discussion on screamers last year I created a similar spreadsheet where I assumed that friction on top runner would lead to a 3:2:5 ratio between forces on climber, belayer and top runner. This ratio is based on the capstan equation, and I believe it is widely accepted. With input from the above example (100 kg climber, fixed belayer, Petzl Contact etc.) I have calculated the rope modulus to be 20.7 kN leading to a max force on climber 6.5 kN, force on belayer 4.4 kN and 10.9 kN on top runner.  Still, the top pro would have to be pretty solid!

Back then when I crated my spreadsheet I focused on the climbers potential energy against the work done by screamer and rope in order to calculate the max force on the top runner in any given fall. I think perhaps your spreadsheet will help me improving mine, and I am looking forward to receive a copy.