In yet another ATC v. Grigri thread, folks are once again claiming grigris are bad for trad belaying because they are less dynamic and can cause gear to rip. Does anyone have an actual example of this happening, where they think an ATC would have made the difference? I've never heard of this, but we've ALL heard of belayers futzing up and dropping people with an ATC (ever try to hold a factor 2 fall, it's not easy!), and it seems within the realm of possibility that your belayer could get a rock to the noggin, in which case a Grigri has obvious benefits.

In yet another ATC v. Grigri thread, folks are once again claiming grigris are bad for trad belaying because they are less dynamic and can cause gear to rip. Does anyone have an actual example of this happening, where they think an ATC would have made the difference? I've never heard of this, but we've ALL heard of belayers futzing up and dropping people with an ATC (ever try to hold a factor 2 fall, it's not easy!), and it seems within the realm of possibility that your belayer could get a rock to the noggin, in which case a Grigri has obvious benefits.

NOTES FROM THE WORKING GROUP ON BELAY METHODS
UIAA SAFETY COMMISSION

Introduction

The Italian Commission for Material and Techniques (CMT) of the Italian Alpine Club (CAI) has been at the forefront of investigating belay methods for a number of years. They carry out their research at a test tower in Padova and at a carefully surveyed rock face, where the topography as well as the location of every protection point (runner) is precisely known. The latter allows the calculation of the friction in the system (as the rope angles change) and thus the tension in the rope as it changes from one protection point to another (chain multiplication factor; force ratio at belayer and top runner). This then permits the calculation of the effective fall factor. The Commission is also developing a theoretical model of belaying.

During the tests numerous parameters are recorded, among them: rope lengths and angles from runner to runner to the falling mass (geometry of safety chain); distance from brake to hand; free fall height; mass of belayer (operator); belay device and technique used; operator position (hanging or standing); stance load; load on last runner; total slippage in the brake and hand; amount of operator lifting (from a standing or hanging position); theoretical (or geometrical) fall factor; force used in holding the rope.

Various belay techniques are employed. The belay device can be attached directly to the operator (body belay), to a fixed point (bolt at the stance) or the belay triangle (an equalizing sling from two stance anchors), while the operator may be attached to the belay triangle or a fixed point. In addition the rope from the brake may be clipped into the belay triangle or a fixed point (dummy runner) as it passes to the leader.

The 'body' has a mass of 80 kg; the fall heights varied from 4 to 12 m and the theoretical fall factors between 0.2 and 0.7. The rope was replaced after no more than two fall tests. The CMT also uses stunt men (climbers with a lot of nerve) for some of the tests instead of a mass.

It should be noted that the tests are only done for pull up. The fall factor two situation, where the leader falls directly on the operator, has not been investigated. It should be kept in mind that for such a scenario most belay methods would fail, because there is insufficient friction in the system to stop the fall.

The main belay devices used are various Sticht types (tuber, ATC) the Grigri, and similar predominantly static devices, as well as the Munter hitch.

It is not surprising that the meetings of the Working Group on Belay Methods of the UIAA Safety Commission have taken place in and around Padova. Canada has participated in the last three meetings. While there are still many questions to be answered, one can report on a few of the findings (in no particular order).

1. The greatest variable in the magnitude of the force at the top runner is operator behaviour. Values can vary between 20 to 50 percent. Hand pressure and position, reaction time, position of operator and body mass have significant influences.
2. All belay devices seem to work, although the force in the top runner may vary.
3. The force in the top runner is surprisingly small (even if there is only one runner, i.e. very little system friction). It appears that the force in the top runner will rarely reach 10 kN (it did not even come close in the tests). The values fall mostly between 3 and 6 kN. This is independent of fall height (theoretical fall factor). Note again that operator behaviour has a major influence.
4. The 'static' devices such as the Grigri (there may be rope slip through the device of 2 to 5 cm, while it is 50 to 120 cm for a dynamic device) may produce twice the force on the last runner than a dynamic device.
5. The lifting of the operator may reduce the force on the top runner, possibly by as much as 10 % and even more. It is again influenced by operator behaviour. Sometimes no significant reduction could be determined.
6. Lifting of the operator beyond 30 to 40 cm has no influence on the magnitude of the force in the top runner.
7. Lifting of the operator may increase the stance load. These forces are, however, not very significant. Generally from two to three kN except for the 'static' devices, which could produce twice these values. The latter were always attached to the fixed anchor, because of injury concerns.
8. The force on the top runner increases with the mass of the operator.
9. It is highly recommended that a dummy runner is used at the belay.

A final word of caution: while many climbers seem to prefer the body belay in the hope of reducing forces on the last runner, the danger of injury may negate this advantage, particularly in alpine, rock, environment. Several injuries to the operators - and they are very experienced - have occurred because of the uncontrolled lifting. One has to keep in mind that they know when the mass is dropping. Now consider when this force hits without this awareness.

The ACC library has a video (with Italian commentary) from the CMT showing some of the belay testing. It is a few years old, but does give an idea what happens to the operator when holding a fall using a body belay.

i.e., the rock knocking your belayer unconscious = gri gri (although i would wonder what the hell you would do with a unconscious belayer who now has you locked off while your 80' in the air?)

folks are once again claiming grigris are bad for trad belaying because they are less dynamic and can cause gear to rip

Try some tests with the Fall Simulator on the Petzl website with some smaller nut strengths and see what happens when you compare a grigri with a tube device.

NOTES FROM THE WORKING GROUP ON BELAY METHODS
UIAA SAFETY COMMISSION

...

4. The 'static' devices such as the Grigri (there may be rope slip through the device of 2 to 5 cm, while it is 50 to 120 cm for a dynamic device) may produce twice the force on the last runner than a dynamic device.

...

In yet another ATC v. Grigri thread, folks are once again claiming grigris are bad for trad belaying because they are less dynamic and can cause gear to rip.

I've never heard of this, but we've ALL heard of belayers futzing up and dropping people with an ATC

Wow, have to call complete bullshite on this - and I don't give a rats ass who claims to have done the study.

'50 to 120 cm' is roughly 20-47 inches of rope. In 34 years of catching lots of long and hard lead falls - including a few falls directly on me before a first piece could be placed - I've never experienced rope slippage of that magnitude. Ever. An inch or two max due mainly to stretch through the device, but that's it.

Many, many of those falls were even on hip belays augmented with a single non-locking biner on the harness on the side of the rope coming from the leader - same deal, completely locked off, no slippage other than regular rope stretch.

From straight stitch plates to today's fancy ATC's, if anyone experiences anything like these kinds of 'slippages' then they aren't locking off the device or braking the rope over their hip. If these sorts of stats were a regular occurence we'd be seeing no end to second and third degree burns of folks hands on their way to becoming competent belayers.

1. The greatest variable in the magnitude of the force at the top runner is operator behaviour. Values can vary between 20 to 50 percent. Hand pressure and position, reaction time, position of operator and body mass have significant influences.

"gri gri causes gear to rip!" - i don't think so. gri gri causes poorly placed gear to rip. whats that old story about some early hardmen from yos try to yank gear out using somebody's VW bug! bumpers were being yanked off the car, cams distroyed and forever "in situ". is that a halo? looks like a punk rocker with a paper clip through his head.

seeya

Wow, have to call complete bullshite on this - and I don't give a rats ass who claims to have done the study.

'50 to 120 cm' is roughly 20-47 inches of rope. In 34 years of catching lots of long and hard lead falls - including a few falls directly on me before a first piece could be placed - I've never experienced rope slippage of that magnitude. Ever. An inch or two max due mainly to stretch through the device, but that's it.

Many, many of those falls were even on hip belays augmented with a single non-locking biner on the harness on the side of the rope coming from the leader - same deal, completely locked off, no slippage other than regular rope stretch.

From straight stitch plates to today's fancy ATC's, if anyone experiences anything like these kinds of 'slippages' then they aren't locking off the device or braking the rope over their hip. If these sorts of stats were a regular occurence we'd be seeing no end to second and third degree burns of folks hands on their way to becoming competent belayers.

well i took a 60' fall while on a grigri, one piece popped but it would have popped anyways...
(i stupidly already used all my gear of that size and could only get 2 lobes in the crack)

as far as catching a fall.. the biggest fall i've ever caught (and with an atc) was 20'
I can't imagine how hard it was to catch a 60 footer (and without the extra braking power)

[maybe i'm wrong..]

gabe - i am saying i don't think the semi-dynamic belay afforded by using the grigri adds enough force to pull good gear.