UKC

What's a good number of kn rating for a medium sized lob? 

I feel like this isn't a straightforward question and will be nuanced between amount of rope out, rope elasticity, how soft is the catch etc.

But what does UKC think. And what other factors may I have overlooked 

Between 3 and 7.

The ball park numbers I've heard are 2kN for a soft fall up to about 6kN for a hard fall, though obviously a lot of leeway in these numbers depending on circumstances.

 this mayhttps://www.youtube.com/watch?v=Tnk4Ky-D9Bg&t=731s&ab_channel=Ho...

help

Petzl’s take

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

You mean, apart from the most obvious one of all? - How many pies you are in the habit of inhaling.

In reply to your first question and purely in my opinion:

2kn - aid only and terrifying as hell at that.

3kn - might hold in a perfect placement if you slump on it and no more.

5kn - probably ok for a small fall.

7kn - probably ok for a medium fall.

9 or 10kn - probably ok for falls up to 80 metres.

Your definitions of small, medium and large are kinda terrifying! I think most people would consider 7kN a pretty large fall.

How many pies have you been inhaling?

The pie eating goes without saying haha

Might hold or might break? Gear is rated for breaking, not holding. I tend to think that once you get to a number three wire or any normal sized cam (ie small blue), the real issue in an average fall is going to be whether the gear holds rather than whether it might break. 

Do you mean the force on the belayer, climber or top piece? These are all affected differently but the type of belay device, the size of fall (fall factor) and the amount of rope drag will make a difference.

A top piece will see between 3kN with a manual device in an FF0.3 fall with minimal drag to 6kN with the same FF with a Grigri and rope drag. A free running rope with a Grigri but a FF1 fall will be approx 6kn too.

There are a lot of factors involved!

Last time I checked about 112 but that was a number of pies ago and I'm too scared to check again.

Ah, maybe I didn't explain that properly. What I meant was that I think for me personally it would probably be ok to take a medium fall onto a 7kN piece of kit in a good placement, which is to say the impact I would expect to put on the piece should be a fair bit under 7kN. Personally, if I thought I was generating 7kN, I wouldn't be happy taking that fall onto a 7kN piece.

Also, yes, this is a pretty unscientific topic because the difference between "medium fall", "big fall" and "m-m-m-monster whipper" is going to vary a lot by person and if we're being honest, probably by route too. If it's a clean overhanging wall that looks like The Big Issue and has good gear, your "small fall" might be a good bit bigger than if you're on a standard-ish VS with slabs, bulges and ledges lurking everywhere and just ready to reconfigure your ankles.

Which bit of the belay are you interested in?

Assuming it's not the dreaded 'factor two', fall past your belayer then it'll be the running belay that sees the highest load.

In principal it's possible to get into double digit kN loads there, in practice it seems rare for gear to actually snap through simple overload. Big, high fall-factor falls have plenty of opportunity for things along the rope to give a bit, they don't seem as hard as the theoretical fall factor might suggest. Small, hard, free falls with high FF feel nasty but that's partly because your floppy body is actually absorbing quite a bit of the energy, limiting the forces in the belay, again, anecdotally looking at the gear that survives, they don't seem to spike as high as you might simplistically expect.

All that is to say IMO mid-high single digit kN rated runners are unlikely to snap unless abused badly but given much of British climbing is on softer rocks and lower rated bits of gear tend to be smaller ripping them out in a fall remains a risk worth seriously considering.

Not sure what you've overlooked but there are myriad ways in which gear can be abused or damaged so it fails prematurely.

jk

https://www.ukclimbing.com/forums/rock_talk/fall_forces-760379

I agree completely with this. I've certainly damaged gear after taking falls onto it a number of times but I don't think I've ever broken anything that wasn't rusty situ crap (knock on wood). However there have been quite a few times where either the rock has broken or the placement has just popped out.

Just a slight point of pedantry - the fall factor doesn't 'measure' the size of the fall, but the severity. Everything else is probably as close an answer as you'll ever get.

If you're generating >=10kn on the climber then a trip to A&E could be in order

Agreed and misleading on my part. I used size to mean severity but it implies length of fall. 

As a sort of side note to this, from recent practice experience of a medium fall on to small gear its definitely somthing to be very aware of. I had a BD micro stopper #3 at my feet whitch I thought was bomber but  slightly deformed and ripped straight out the bottom of the crack it was in when i lobbed off. The BD #5 a foot or so below it held, but both nuts ended up with 3 or 4 snapped individual wires.

You do fall practice on microwires?

Notthing practiced about that fall! I was off route, pumped and desperately slapping for my life! Bloody inches from jugs as well. (Leson to learn is read the sodding guidebook)

I fall off enough normally without feeling the need for practicing it...

The only gear I've seen failing in any videos or articles I've read about have been less than 5kn. Robbie Phillips recent gear breaking fall (actually Alex's) broke some 5kn gear but it was a big fall and he was using Edelrid's aramid rope which adds about 30% to fall forces. 

I use 5kn as a "don't go below" for normal use.

We were discussing this climbing at Castle Naze Saturday morning. My friend had BD alloy micro nuts - the smallest one has 2 kn rating, the next one up is 5kn. I've got some of the BD soldered brass nuts and they are something like 6kn for about the same size. I don't carry the smallest wired alloy nuts I had (wall nut 00, 0, 1/2 I think they are)  that aren't brass/soldered anymore when I realised how low their cable strength actually is. 

You've changed two variables at once here, so one may be overshadowing the other. For clarity, assuming both were on the same belay device, would you expect higher load on the top gear piece with or without rope drag?

And for an additional mark, please explain your answer.

Ta.

Higher force factor with drag because the effective amount of rope available to stretch is less.

As AJM said above, more drag increases force on your top piece, decreases the force on your belayer and the force on you, the climber, stays about the same.

This is due to the effective length of rope that the force can dissipate along is reduced by the rope drag. Increasing drag effectively increases the FF. Petzl did some great tests and its effect is more pronounced than I had appreciated.

Yeah, I stopped carrying my old Chouinard #2's too when I realised they're only good for 2kN

the larger soldered brass nuts like the HB Offsets and IMPS are amazing for their size... Probably rock limited in many placements!

Brass are shit at staying in position sometimes, I lead most of LBG with no gear at all when it all fell out because I was using my new brass nuts.

I don't take them out with me now, although 2kn is pretty shit, it still slows you down and they stay in place. I used one the other week and it was fine, mainly because I never fell off

But it was enough to get me up a little further where I could place more and better gear.

Place enough of the microwires and eventually both ropes will become tight together and the load will halve. I've seen leaders place 20 microwires with this in mind.ive not had to resort to that but I guess it works.

Weird, I've generally found the opposite - the slight softness of brass makes them 'stickier' than alloy. 

Perhaps people have problems feeling a good 'fit'. It's a lot easier to get micro's caught on a single grain or crystal rather than with good contact.

I read through the responses and think I can add a thought.

Wouldn't one, during a climb, be inserting all the possible gear ? Assuming that one has the requisite cams, nuts, wire for a given route, why would one not place all the gear ? And once you have placed all the gear, it matters little its KN rating because it's as good as it's going to get ?

You query supposes that (a) you don't have the strongest versions of all necessary gear types and (b) you don't place all the possible gear ?

Helpful ?

Wishing a great weekend to all !

With a quick draw through each of them??!?!?

Brass (55) is much harder than aluminium (20-25), but each to their own.

No, because if you placed all the gear, then you might not have the piece you need further up. Besides if the gear is "bomber" then why place more?

You place gear to stop you getting smashed up, so you can space it out more as you go up (if you're brave enough), and Using all you can, only means you spend more time placing and removing gear, than actually climbing.

What test/units is that for? No idea of the brass alloy used but bearing in mind the aluminum used is 7075 for micronuts or 6000 for the standard nuts (I believe) they are quite hard (7075 harder than the 6000 series, obvs)?

No because you'd soon burn through all your gear. What if you need a bit further up that you've used "because you could" lower down?

Rockwell, hardness.

I think it's due to the small bend radius around the nut

Try placing gear while doing something strenuous (like laybacking) and you'll see that sometimes placing gear could tire you and even make it impossible to do or make you fall off.  Although at my lowly grades that's less of a concern that people pushing it really hard 

7075 is Rockwell B 87 so harder than “brass” at 55, though no idea what “brass” the micro wire are actually made of! 6061 (used for the bigger nuts I believe) is Rockwell B 60 so comparable to brass. 

Simon Marsh (DMM) did a really good post on this years ago basically saying it’s neither the bend radius nor the solder strength but the diameter of wire you can get into the base of the nut.

• 1.5mm - ~2kN
• 2.0mm - ~4-5kN
• 2.5mm - ~7-8kN

He also explained why at IMP/RP3 (i think) the strength benefit fully flips back from IMP to micro nut (placement shape not withstanding).

Having said all of the above, I also believe that the main failiure mechanism for small gear is then gear pulling through so kN might not be the key factor to consider.

Will have to goggle the OG post…..

In my thought was the idea that you'd taken with you all the necessary gear - so you wouldn't run out (pun intended) cos you're at max gear all the way.

Only when you don't have all the gear necessary would marginal gains of a few kn here and there per piece would make a difference.

It's almost always possible to carry enough gear to adequately protect a route (assuming it's a route where sufficient placement possibilities actually exist). It's very rarely possible to carry enough gear to utilise every plausible placement on the route*. So it's always going to be necessary to make judgements about how adequate the placements you've made are. And even in a situation where you've utilised every possible placement, there'd still be a judgement call to make about whether to carry on or back off.

*In fact, on a lot of routes it would be difficult to even own enough gear to utilise every spot, let alone carry it all.

There are some routes where it would be tempting to see how much gear can be placed, rather than just placing sufficient gear. Lost Horizon (VS 5a) at  Baggy Point comes to mind but there must be plenty of others.

To use an empirical method, my aluminium nuts have small indentations and dents, my brass nuts look brand-new.

Few have been fallen on, so these are from placement and removal only.

Since you rarely know, what's ahead of you, if you are on-siting, how could you take "all" the necessary gear. At best it's a "hope" you've got everything you need.

Besides all that you place what you need, not what you can.

I placed all my gear on one route last year as an exercise in selecting the correct piece each time. I can confirm that on any particular hs at subliminal it is possible to place everything somewhere.