UKC

Has anybody tried using a Grigri 2 (to belay someone or to abseil) on a skinny 8mm rope?

Manufacturer says not to go < 8.9 mm, but a lot of descending devices etc. say that on the side, but work fine in practice on an 8mm line.

Thanks guys,

Rapsling

In reply to Rapsling:

It's very unlikely you'll be belaying someone who's leading on an 8mm single, and there are better ways to ab than with a GriGri, so I'd suggest not using one in either of those situations.

In reply to Rapsling:

If saving weight is important enough to you that you would use an 8mm rope, why use a heavy GriGri?

In reply to purplemonkeyelephant:

You and @Fraser raise excellent points, and I think your observations are perfectly valid. I'm trying not to go into too much detail about my plans, as this site can get a bit troll-y if you're not careful, but the original question is still relevant to me. I'm hoping someone here knows if a Grigri 2 will auto-lock if an 8mm dynamic rope is pulled through it at uncontrolled speed, so if you've tried using this bit of gear with this kind of rope, I would be very interested to hear about your experiences.

Again, your point is perfectly valid, and my reiteration of the question is in no way intended as a criticism of that.

Thanks,

Rapsling

In reply to Rapsling:

try it out....?

should be easy enough to arrange unless you dont have a grigri 2 and an 8mm rope

In reply to Rapsling:
I've just dug out my fairly unused half rope which is about 8.3mm diameter and stuck it through my Grigri 2.

It didn't even come close to locking so hopefully that answers your question on the abbing front. You could obviously use it still to belay someone but you'd definitely need to treat it as a conventional tube belay device as it wouldn't lock.

HTH.

In reply to Fraser:


Grigris loaded backwards make really crap tubes, even with ropes of the recommended thickness, as many people have found out the hard way. Not convinced they'd be any better loaded forwards.

In reply to Rapsling:

You may be better off using a Megajul as that is designed to be used with half/ twin ropes. I've never tried getting mine to lock up on a half rope but can't see any reason why it wouldn't work with the right carabiner . I can do a quick experiment with an 8.3mm rope this evening if that would help? If you explain what you are wanting to use it for people may well be able to provide you with a workable solution.

In reply to spenser:
>Manufacturer says not to go < 8.9 mm, but a lot of descending devices etc. say that on the side, but work fine in practice on an 8mm line.

Which ones? I do research into belay devices and can´t offhand think of any that give even satisfactory braking performance near their lower limit let alone below it. About the only one is the GriGri 1 which is sort-of o.k with 9.8mm.


I can save you the effort, the MegaJul goes into the locking position (sometimes) but the braking resistance is minimal, without a belayers hand force it´s 0.037kN (3.8kg) for an 8mm single strand. With a belayer gripping as hard as possible then 0.7kN (72kg).
The best I´ve tested is the CT Alpine Up which gives 0.72kN(74kg) unassisted and 1.29kN(132kg) with a belayer. Locking is not guaranteed unassisted

In reply to AlanLittle:


Are you sure that's what Fraser meant?

In reply to jon:

Err, thanks Jon, you're right - I think I meant using the Grigri in the conventionally loaded manner, not backwards. Personally I'd not use a Grigri for abbing, in any orientation, but that's just me!

In reply to jimtitt:

Thanks Jim, that's less than I was expecting.

In reply to Rapsling:

Since you haven't really said for what purpose, i can't give you any advise.

But there is a Grigri like thing for 7.5mm rope. The Petzl Exo kit, comes with it's own rope and such. Not de belay device though. It has a additional loop where the ropes run though.

In reply to Fraser:

Thanks very much for your help, Fraser and everyone. Very kind of you.

In reply to jimtitt:


That's...surprising. I would say GriGri1 is sort-of ok with 8.9mm (yes, it did lock) and works perfectly fine when used on 9.1mm Joker

In reply to jimtitt:



Hi jimtitt,

Thanks very much for your advice, it's very nice to hear from an expert!

I have found the Petzl Reverse 4 to work acceptably on an 8mm single strand (c.f. manufacturer's guidance 8.9mm), and on a 6mm double-stranded abseil (Petzl advise >=7.5). By "work acceptably" I mean I was able to abseil without falling off and going splat, not that I could reliably catch a high-impact-force leader fall while belaying.

I have also found the Rock Exotica Silent Partner to lock reliably with an 8mm dynamic line, when the manufacturer recommend no less than 9.8mm.

I understand that this kind of anecdotal evidence doesn't compare to your scientific approach, however, so I'm very grateful for your input. I think you guys have managed to talk me out of using a Grigri 2 with an 8mm line, so thank you very much to all of you for your time.

In reply to Rapsling:

I have used a Grigri2 on an 8 or 9mm rope (not sure which it was when I bought it). (Not for belaying another person; as a home-made work positioning adjustable lanyard).

The grigri's assisted braking took a lot more to become effective / begin to cam, and came off significantly easier than with thicker / heavier per metre rope. The cam seemed to need a lot more persuasion to go to work. With an attentive belay control hand on the control rope it would still do the job of assisted braking, but it made me and my colleague quite twitchy.
I wouldn't recommend going extra skinny with a grigri unless for expert use in acceptable scenarios.

Hope that helps Rapsling. Nice work on keeping trolls at bay and being courteous to those who replied to you. Nice to be important, more important to be nice and all.