It doesnt take too much searching to find people saying something along the lines of

"dont use a gri-gri on gear because it's not a dynamic belay"

soon after there may be a post like this:

"I belay on gear all the time with a gri-gri, and my partners are still alive"

I want to test this. Does the gri-gri really matter: does the inch or two of rope slipping dissipate enough energy to make a difference in the peak force of the fall?

I feel like it's fairly easy to test this is a pretty real world situation. Setup a force meter on the top piece, have a weight attached to a rope, and have a real person attached to the other end. Drop the weight from several heights, simulating real world fall factors (including something close to FF2). There would be some safety precautions that would need to take place but it should be doable.

Let me know what you think. What suggestions you have, or links to an article with similar tests. I'm not interested in someone spewing about their beliefs, i'm interested in numbers. Also, dont link me the petzl fall simulator, i'm not talking about the case when a leader takes a whipper on a gri-gri attached to the anchor, im interested in whipping on a gri-gri attached to the person.

note:substitute cinch for gri-gri if you want...

I want to test this. Does the gri-gri really matter: does the inch or two of rope slipping dissipate enough energy to make a difference in the peak force of the fall?

My assumptions and their backing:

Cinch vs grigri: they both lock on the rope quickly, and in most cases don't let the rope slip (i know the cinch slips under high FF, if we want to test that, go for it, i'm trying to minimize the test cases) I think most people thing of the gri-gri and cinch as interchangeable when they're talking about dynamic vs non-dynamic belays

"inch or two of slippage" when i catch a fall on an ATC my brake had is typically gripping the rope less than 5-6 inches from the device both before and after a fall. The max distance that my hand would be down the rope is in the 1.5 feet range (again, approx). Given the fact that i dont notice much slippage, and how much rope is in play elsewhere in the fall, i'm hypothesizing that there is very little slippage in a typical fall. I'd like to test this hypothesis as well. I'm sure it will be a function of force, but what would the typical and worst case scenarios be?

In a "typical" fall, if you are using an ATC, and you actually know what you are doing (which is rare), you have the option of allowing as much rope as you like slide through the device to provide as dynamic a belay as you want, including the option of letting no rope slide through the device. That's one reason that Grigris aren't a good idea for trad; you never have the option to provide a dynamic belay.

Jay

In summary, as with a number of issues in climbing (equalizing belay anchors, backing up rappels, wearing helmets, etc.), there are practices that are effective a large majority of the time but which may not work well or at all in a very small number of exceptional cases. Since the rope doesn't slip in most climbing falls, there is usually no difference in imposed peak load for a Gri-Gri and ATC-type devices. However, in high fall-factor low-friction circumstances, the rope slippage is a potential safety valve that may keep peak loads within the limits sustainable by trad gear, where as the same gear will blow with a Gri-Gri. I say "potential safety valve" because without gloves, it isn't clear that rope slippage will be controllable. If the belayer cannot maintain full strength grip or even loses control, rope slippage becomes not a safety valve but a liability. Moreover, even if the belayer hangs on, the burns sustained can range from annoying to exceptionally severe---as in down to the bone.

Using an ATC-type device rather than a Gri-Gri means (if you were to think logically about it) that you want the potential safety-valve effect that might come into play in exceptional circumstances. Not wearing gloves turns that potential effect into a liability and so contradicts choosing the ATC-type device---at least that's the way it appears to me.

a technique i've seen described, but i've never seen it used. Properly executed, i'd admit, that this would decrease the force on the piece. Just like a properly executed hop during a fall w/ a grigri will decrease the impact force.

I've been looking for the research you hinted at, and i've been unable to find it. I did however find a post by rgold on mountain project. http://theclimbinglab.com/tiki-index.php

The summary paragraph of his post:

which means to me, in most cases, it doesnt matter.

When it comes to high FF, you either use a gri-gri and hope the gear holds, or use an ATC and use gloves.

so will you then agree that in a non FF2 situation ("most falls") it doesnt matter whether you use a grigri or an atc?

i do mostly single pitch trad and sport, so for me, grigri 100% of the time is fine.

i do mostly single pitch trad and sport, so for me, grigri 100% of the time is fine.

From the people i've talked to, they say grigri is not appropriate for even single pitch trad, which is wrong.

cracklover from my understanding seems to think small lead falls on a grigri will equal death.

Of course, that would depend somewhat on the quality of the protection. A drop-in stopper placement in a granite crack is one thing. A TCU in a bomb-bay flare is another entirely.

Has anyone here caught a fall with a Cinch while in "feeding" mode? I wonder if this differs much from the Cinch catching a fall while in it's "locked off" mode.

I curious how accurate this claim is. The whole point of this thread was to get numbers to investigate this.

I have done testing myself, and it is not hard to rip small-to-medium sized cams out of okay but not great placements at under 5kN. Not every time, but a good percentage of the time.

Your problem is that you know everything already, based on, so far as I can tell, exactly zilch. Not exactly the right mindset for learning.

GO

My problem is i cant find any information, thats why i proposed a test.

I dont argue that you can pull out a marginal piece with a grigri. My question is does the grigri really increase the force (as i've heard some people say). The goal would be to find out if a piece would have held if belayed by an atc, but popped because it's was belayed with a grigri.

i dont understand why you say i've already made up my mind. I;ve stated hypothesis that i want tested. obviously i have an opinion, an opinion that can change with relevant data.

I want to test this. Does the gri-gri really matter: does the inch or two of rope slipping dissipate enough energy to make a difference in the peak force of the fall?

note:substitute cinch for gri-gri if you want...

so will you then agree that in a non FF2 situation ("most falls") it doesnt matter whether you use a grigri or an atc?

in a FF2 it will significantly increase the force on the anchor?

i do mostly single pitch trad and sport, so for me, grigri 100% of the time is fine.

From the people i've talked to, they say grigri is not appropriate for even single pitch trad, which is wrong. they seem to have a ur gonna die mentality.

I'd suggest that a good belayer using a GriGri but prepared and able to execute a jump would be able to reduce the impact force far more than a belayer who was aiming to offer a dynamic belay through rope slipping through an ATC. I daresay the GriGri belayer would maintain better control of the rope throughout the process too.