UKC

Hi, I've been using 9.1mm and 8.7mm single ropes recently but find that my belay device (BD ATC guide) does not give as much friction as I want when holding a fall (I'm quite heavy).

What belay devices are best with skinny single ropes? Thanks.

Grigri 2 works well.

ATC Alpine Guide?

Trad or Sport?

If Sport please for the love of god get yourself an assisted braking device.  I like the CT Click-Up but (BBC style) other devices are available.  They all have their pros and cons.

If trad/winter/alpine I'll leave others to recommend, not my bag.... 

.... but the new Grigri works better. It's optimised for a greater range of rope diameters than Grigri2. Check out the Petzl recommendations.

It's for trad and sport. 

If you are using it for trad and sport, the Giga Jul is worth a look. It's assisted breaking, can be used with half ropes/for abseiling, and once you get used to it is really nice to use.

If it's more for sport...grigri. It's the best device out there imo. Can't go far wrong with it.

+1 for GigaJul, to do everything, great with skinny ropes. Not good with fat furry ropes though.

Sounds like a Grigri is the way to go (assuming it's sport climbing you're doing). Belaying with a Grigri is quite different to an ATC type device and takes practice to get it right. It's very common to see crap belaying with Grigri's so defo check out all the advice / tutorials from Petzl rather than copying others at the crag. Assisted braking and auto-locking are very different, the Grigri is 'assisted braking'. Lots can and does go wrong with these.

If you'd prefer an 'auto-locking' device the Wild Country Revo is worth a look: https://www.wildcountry.com/revo-belay-device-40-revo_00000 - it's same as belaying with a standard ATC which is a great feature. Doesn't add much friction though, so may not be quite what you're looking for. If needing to hold a climber with this there is a lever that can be pulled to help take their weight. 

or an ATC Pilot for sport, no moving parts, easy to use and, in my opinion, is easy to learn and less prone to user error than a grigri

Have a look at all of the devices on the market for sport, there’s a wide range and many of the newer types with no moving parts (ATC pilot, Click Up, Megajul etc) are operated in a very similar way to a tube style device so shouldn’t be too difficult to begin to use. Most should be able to deal with modern skinny ropes with no probs.

Not my area of experience, but I think many trad climbers stick with a tube style device for trad. Allows you to slip the rope(s) in a catch more which reduces peak force on the gear making it less likely to come out.

If you want to keep using the atc.

Use 2 similar screw gates (length needs to be the same).

Clip both through the belay loop, and the atc/rope

This will increase the braking "power" of the ATC.

I've assumed I need to use identical dimensions for both krabs. Is the diameter important as well as length, please?

DMM Mantis is worth considering, simple, light, effective

Just the length. 

The Revo is awful with thin ropes and a heavy climber, especially when lowering. Not recommended. 

@OP you definitely want a Grigri. For single rope use there's nothing better. 

Fair enough. My experience with the Revo has been very positive, but maybe I just haven't lowered many heavy climbers with it. Good to know

I seem to recall some semi-scientific tests about this... and if it slips... it'll continue to slip so that the climber craters. So that argument doesn't seem to hold much water.

Harder catch (higher impact force) does have more to it... if you're belayer is a 500kg concrete block. So how the belayer acts plays a much greater impact to this (again, some semi-scientific tests floatin' around).

Which is safer to use, GriGri, GigaJul or pure Tube (eg. ATC Sport). All are good if you use them properly. And all are bad if used improperly. Tube style devices will be better... if you're used to tube style devices. Less of an issue, if you don't have a considerable heritage weighing you around. N.b. I belay with my GriGri just like with a regular tube... guess what, even that can be done...


But if you want to use twin-ropes and half-ropes... then GriGri isn't an option.

Oh, and I use GriGris (orig. and GriGri IIs), ATC Guide, Reversos and bunch of other tube devices. Conditions and need depending. I might not be the best example, but I use primarily my orig GriGri, for trad, sport, ice&mixed. And generally only resort to ATC type stuff when I need to use half-ropes.

My belayer fainted and went face first into the snow within seconds of lowering me off an ice route recently. I won't lie, it has knocked my confidence in non-assisted devices to be honest. 

I would say if someone's changing device anyway, might as well get the safest device. Lead belaying on half-ropes with a GigaJul in assisted mode isn't any more difficult to learn than a GriGri imo.

 

It would be interesting to see those ‘scientific tests’, because your statement seems to contradict my experience. I have successfully performed controlled ‘soft catches’ with a Petzl Reverso, and I’m always prepared to do so when needed. Actually, the technique is not my idea, but I have learnt it from a dedicated sports climber. I wouldn’t recommend it to beginners though.

What device would you advise for ice climbing then? Double rope technique is common and ropes ice up. 

Hard is easy snd How not 2 have something about this in YouTube. 
 

And my local climbing association did some testing a few years back with in-proper grigri technique (thumb lightly on the cam). Falling from 12m was not enough time to react.

GigaJul works great with double ropes and iced up ropes. 

If you can't can't someone in 12m with a GriGri, you shouldn't be belaying, or driving for that matter!

It was a test using invalid technique. But a really good example, If you use the gear wrong, results might not be good.

Are you sure that works? Doesn't having 2 krabs mean you've then got a wider bend radius and therefore less braking power? I sometimes use an extra krab on a runner to reduce rope drag following that principle.

It's worth adding that not only do you have to have your thumb on the cam but also you have to be providing counterpressure and you also have to not be holding the rope.

If you've got the rope tunneled through your fingers, the grigri will brake.

So you have to get the technique utterly wrong - which I'm sure people do, but it's not just a thumb on the cam.

Oh, you meant IMproper technique! Makes more sense.

But even so.....sure it's dangerous to hold the cam open on a GriGri while letting go of the brake strand, but it's no different to letting go of the brake strand on an ATC. You shouldn't be anywhere near a belay if you do it.

It certainly works. I'm no expert but IIRC its something to do with bending a rope, then straightening it then, bending it over the 2nd krab compared to just bending it round one krab. I think Jim Titt explained it in a thread some time ago.

Edit, I think this may be the link.  https://www.mountainproject.com/forum/message/116154681

Edit 2. Its very important to clip the rope and the belay loop with Both krabs since just clipping the rope with one of the krabs will have the reverse effect.

Yes it works. Try it. 

The key is both krabs go through the belay loop and the ropes. If you only clip the ropes not the belay loop as well, you will have reduced friction. This can be useful with a fat old fixed line and a light abseiler.

The more the rope has to bend round the biners, the more friction in the system. Works well when abbing too, if you ever need extra control. 

In a pinch you can use a HMS as an abseil device. You spiral the rope around the spine of the biner, the more wraps, the more friction in descent. Won't do your rope any favours, but it works. Same sort of principle in that the more bent the rope, the more rope on metal friction etc, the more friction in the system. 

Interestingly I think there's a bit more to it. I don't understand mechanics much myself but Jim Titt explained it thus. "Two karabiners side by side is two radii seperated, not a large radius. To bend the rope, straighten it and bend it again takes more force than just bending it once and so the friction increases, for two biners about 8-10%. The effect continues to increase up to around 5 to 7 karabiners and is also why deep tube devices like the ATC XP work better than low profile ones." I gave a link backthread but it may not have opened on that post.

I can't visualize why one gets reduced friction, which certainly does happen, if the second krab clips the ropes and not the belay loop since the ropes appear to run over two krabs in a similar way. Perhaps someone can explain.

Sorry, I intended to enquire about Why two krabs used in this way ( both to rope, only one to belay loop) reduce friction, whereas if both are clipped through the belay loop the effect is to Increase friction.