|
|
|
|
jt512
Jul 23, 2003, 1:17 AM
Post #51 of 118
(7980 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: In reply to: In reply to: As far as purposely letting the rope slip through an atc type device, I have never met anyone that actually tried to do this. Not true. You've met me. Though the master of this technique is Tom Lindner. As I recall you were not using an atc when we were sport climbing. Are you saying that you advocate that technique as a replacement for jumping?
I think the truth is that jumping is a second-rate form of dynamic belaying. Climbers have been giving dynamic belays by letting rope slip thru the device for a long time before sport climbing came about. You can't jump at a hanging belay, but you can let rope slip through your belay device. Jumping mainly is for sport climbing, where the routes are single pitch and the ground is flat.
In reply to: If I had known you did not like to jump I probably wouldn't let you belay me on a route I could fall on.
I usually use a grigri to sport climb and jump to dynamically belay. However, I switched to the grigri for lead belaying outdoors just a few years ago, and prior to that I either jumped or let rope through the ATC. I never jump and let rope through simultaneously, but I have let rope through while taking a couple steps forward to make the belay more dynamic.
In reply to: Is Tom using that technique since he blew his hip out? If I want to give a dynamic catch I use a gri gri or atc and jump, and so does everyone else I know.
No, Tom thinks that grigris are for "people who like to climb stoned." He actually uses a Figure 8 (in rappel mode) to belay, not an ATC. With practice, with an ATC, you can let out as much or as little rope as you want. With a grigri you are limited by the amount you can jump. You actually have more flexibilty and control with an ATC than with a grigri.
In reply to: In reply to: It's very easy to stop the rope with an ATC. You simply move your hand into the full braking position. Keep in mind that you have control at all times. You don't let the rope run at full speed. The device is always providing some friction; you decide how much by the angle between the two strands of rope. If you start with the two strands about 60 degrees apart and smoothly bring your hand down to your hip, you will let a couple of feet of rope through the device, gradually stopping the fall. -Jay I don't see a point in doing that. The most you could let slide is a foot or two of rope, whereas with a jump you can do four to ten feet of rope without a risk of loosing control of the rope.
Like I said above, you can let out as much rope as you want using an ATC and at any speed you want. It takes practice and a belay glove. You vary the speed with the angle between the ropes, and the length by how fast you bring your hand down to your hip. You do not lose control of the rope. The ATC stops the fall, not your grip strength. Even with the rope running through your hand, if you bring your hand back to your hip, the ATC locks up.
-Jay
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 2:00 AM
Post #52 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
Jay,
I wouldn't let someone belay me using that technique and if I saw someone keeping their hand in front of the device, I wouldn't fall.
As far as multipitch, I just leave a big loop(unless there is a ledge) and don't worry about any fancy belaying technique beyond catching them if they fall.
|
|
|
|
|
mewalrus
Jul 23, 2003, 2:02 AM
Post #53 of 118
(7980 views)
Shortcut
Registered: Jun 11, 2003
Posts: 132
|
In reply to: Right. But as was already pointed out, this is only if the grigri is directly hooked to the anchor. If you are belaying with the grigri attached to your waist, you can't generate more force than body weight (ok, as somebody pointed out--if you are being accelerated, you can produce more force than your weight, but it won't be much). This means if you catch a fall with a grigri, you might get lifted off the ground but you won't be applying much more than a few hundred pounds (unless or until you come tight on your anchor or you get lifted all the way up to the first bolt).
I am pretty sure you are dead wrong on that one. Force and weight are two very different concepts.
|
|
|
|
|
jt512
Jul 23, 2003, 2:10 AM
Post #54 of 118
(7980 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: Jay, I wouldn't let someone belay me using that technique and if I saw someone keeping their hand in front of the device, I wouldn't fall.
That's the standard way to belay a leader with an ATC, Dan. Only gumbies keep the rope locked off all the time, unless their partner is moving at a snail's pace. It's the rope-behind-the-butt-all-the-time belayers that you should worry about. They'll short rope you on every move.
This is how it should be done (cute tilting of head is optional):
http://www.rockclimbing.com/...mp.cgi?Detailed=3810
From this position, she can lock off or feed rope instantly. To dynamically belay, the hands should be kept further from the ATC, but the angle between the ropes is correct.
-Jay
|
|
|
|
|
elrojobdugs
Jul 23, 2003, 4:05 AM
Post #55 of 118
(7980 views)
Shortcut
Registered: Jul 19, 2003
Posts: 141
|
does anyone here use both hands on the slack part... or seen anyone doing so... i recently was at a gym and two guys were doing it... whats up with that... theyd pull straight up with the slack with both hands and go into brake position...???
|
|
|
|
|
traddad
Jul 23, 2003, 1:14 PM
Post #56 of 118
(7980 views)
Shortcut
Registered: Dec 14, 2001
Posts: 7129
|
Jumpin' Jay,
She can belay me any time. You and your double back flip with a full twist belay method on the other hand... :twisted:
Let me guess, you never get more than 80 feet off the ground, or more than 20 feet fom the bumper of your car.... :P
|
|
|
|
|
sticky_fingers
Jul 23, 2003, 1:52 PM
Post #57 of 118
(7980 views)
Shortcut
Registered: Jun 17, 2003
Posts: 420
|
In reply to: Have you ever tried to do a squeeze chimney with a gri gri on your harness?
To be honest, no, I've never done a tight chimney. However, from all the videos and pics I've seen of people climbing (seconding?) tight chimneys, I'd imagine I'd put as much "big" gear on the outside of my harness as possible, including fatty cams, bros and gri-gri.
|
|
|
|
|
traddad
Jul 23, 2003, 2:05 PM
Post #58 of 118
(7980 views)
Shortcut
Registered: Dec 14, 2001
Posts: 7129
|
Squeeze chimney? You're going to worry about a gri gri when your humping a rack of #5 Camelots, big bros and Valley Giants?
(There, I mentioned Valley Giants....do I get a discount?)
|
|
|
|
|
redpoint73
Jul 23, 2003, 2:08 PM
Post #59 of 118
(7980 views)
Shortcut
Registered: Aug 20, 2002
Posts: 1717
|
In reply to: does anyone here use both hands on the slack part... or seen anyone doing so... i recently was at a gym and two guys were doing it... whats up with that... theyd pull straight up with the slack with both hands and go into brake position...???
Yeah, I've seen that at the gym as well! And I seem to be noticing it more recently. It seems inefficient if you need to take up slack quickly, but I don't belay that way, so I can't really say. I have heard some of those belayers state "that was how they were taught".
Those folks seem less experienced. They will likely find that once they get outside and need to belay a leader, that they will have to totally relearn how to belay. Now learning how to lead belay takes some practice regardless of your TR technique, since you are mostly throwing out slack instead of taking it up. But these guys will have to completely rethink their hand position and movement.
|
|
|
|
|
markc
Jul 23, 2003, 2:44 PM
Post #60 of 118
(7980 views)
Shortcut
Registered: Jan 21, 2003
Posts: 2481
|
In reply to: Too heavy and bulky?????? gimme a break i just went on REI's home page where they list a BD ATC (not XP) as weighing 49 grams and a gri-gri weighing 225 grams Bottom line: A gri-gri is only 176 grams heavier than an ATC. [Snip body weight analysis.] If an additional 0.25% of your body weight is too heavy for you to carry, get off the rock. Besides, YOU'RE BELAYING not leading. If the only reason you can't second a climb is because you have to schelp a gri-gri, then you have other problems. Bulky? what and carrying a rull rack is like a second skin? remember you're belaying. when you climb (if you follow) you begin with NO gear and pick it up as you go. Most likely you'll end up with less than the full rack because the leader probably carried more than he/she needed to. I'm not trying to sway anybody's opinion, I'm just trying to thow out the arguments that's it's too heavy and bulky.
You make multiple references to seconding. When I climb, I'm either switching leads or taking them all. What do you suggest I do with my gri-gri whilst leading? If I'm climbing with the thing, I might as well belay my second with it. Besides, it's because of the bulk of the rack that I don't want that much excess baggage. I already carry more pro than I need, why bring two belay devices (one of which I can't rappel with)? I'm not an ounce-shaver, but my "might as well" attitude has limits.
If I'm on a multi-pitch route, I'm going to need another device (or gri-gri shenanigans). A gri-gri AND another device will be heavier and bulkier than one. You might not mind it, but that's still the way it is. Carry what you will, but don't ask me to lug your gri-gri if the next pitch is looking a little heady.
mark
|
|
|
|
|
sticky_fingers
Jul 23, 2003, 3:32 PM
Post #61 of 118
(7980 views)
Shortcut
Registered: Jun 17, 2003
Posts: 420
|
markc: Point taken, but I was presuming that the leader would carry up a lighter device (ATC, knot, etc) to belay with, while the second could easily follow with a gri-gri, and not be held back by its weight or size. Hell, the second could even carry up an ATC. :shock: Maybe it's not the most convienent, but I'd bet dollars to doughnuts (haha my dad's expression) that if you were leading and something konked me on the head, you'd wished I had my hands on a gri-gri rather than an ATC.
Look, the original post was about wether or not belaying on trad with a gri-gri was considered dangerous. Now it's gotten into a convenience thread. I can't imagine anybody reading/posting on rc.com in a more inconveinent position than climbing a possible 15a without part of a finger (i know, i know...sport/trad), so until somebody gets shut down by gear weight/size, i think this is a silly discussion. I don't think anybody can make a case where the increase in safety afforded by a properly loaded gri-gri is not worth it's wight/size.
|
|
|
|
|
markc
Jul 23, 2003, 4:02 PM
Post #62 of 118
(7980 views)
Shortcut
Registered: Jan 21, 2003
Posts: 2481
|
Well, Mr. Fingers, we'll have to agree to disagree on the gri-gri issue. I'm the first to admit it's not my preferred belay device.
Happy climbing,
mark
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 4:08 PM
Post #63 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
Sticky-fingers
If your in a real squeeze chimney you want to hang "all" your gear on a long sling hanging from your belay loop.(lead or second)
As far as the rockfall thing, if you knock your belayer out with a rock you deserve to get hurt as far as I am concerned. A helmet and a gri gri does very little to help things, your much better off not knocking rocks down in the first place. Rock fall usually kills the belayer not the leader, and if a leader thinks a belayer using a gri gri makes him safer I wouldn't want to belay him.
|
|
|
|
|
tenn_dawg
Jul 23, 2003, 4:17 PM
Post #64 of 118
(7980 views)
Shortcut
Registered: Mar 14, 2002
Posts: 3045
|
In reply to: Chris Harmston wrote In reply to: The MH is one of the most static belays available. This can be very dangerous when you must rely on the dynamic belay. In trad and ice climbing the MH can be very dangerous because it will increase the loads felt by the top anchor. Different post (snip) Here is another example of some "uncontrolled" testing I have been involved with. Last winter Craig Luebben and I conducted some drop tests on ice. Craig published an article in Climbing Mag on some of these results and results of his static tests. I have also written an article on static tests I have conducted in the lab (email me if anyone wants a copy). Anyway, we set up our tests under the bridge in Ouray. This was in pretty bad ice actually and for the most part the gear did not hold. Our setup was with a static belay, a new 10.5 mm BD rope, fall factors in the 1.5 to 1.8 range, and 185 pounds of steel. With this setup the only thing that actually held was a 10 cm screw. Everything else ripped out OR carabiners broke! I attribute this to the bad ice and that the 10 cm screw that held was probably in the only good ice we found. We decided to conduct a series of tests where we used the same section of rope over again. The first three tests the gear ripped out. On the fourth drop we about keeled over in disbelief. We had a Snarg as the test piece connected to the rope with a draw with BD QS2 biners. A few feet below this was two equalized screws (BD and a Grivel). They were equalized with a single 24" sling and a locked Big Easy was connected to the rope. The biner on the snarg broke, the hanger on the Grivel screw sheared along its long bend, then the big easy locked biner broke! This is three pieces of hardware that broke on one fall. Now, I am assuming that these were not defective products (a solid assumption based on my knowledge of all the gear and the systems to produce it, and a review of the fracture surfaces of the parts we actually recovered). This means that the forces generated were well in excess of 5000 pounds (multiple times!). Now the tricky part. Conducting a static test on a new rope with the same diameter with the same type of knots caused the rope to break in the 3500 pound range. I don't know why the gear broke and why the rope did not. There was about one hour between drops so the rope had some reasonable time to recover. Now the good news. When we placed an ATC in the system (i.e. some dynamic aspects) every test we conducted held except for a couple of tests with Spectres. What does this mean? Dynamic belays are your friend! Climbers have known this for about a century now. Many climbers today do not understand this very well. This is why I am relating these types of info to this news group. I am purposely trying to get this group to discuss this stuff in detail and learn something from it. (snip)
This "testing" proves nothing. They were not controlled circumstances, and they don't even describe their setup.
To the best I can understand, they were belaying directly off of an anchor, and dropping a weight from a lower height onto a rope to produce aprox. factor 1.8 falls
This has no relevance to forces felt on a lead placement durring a regular climbing fall.
Beyond that, the testing is so unstandardized that I can't believe that it was published in any context.
All it proves is that high factor falls on bad anchors cause failure. Who knew?
Travis
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 4:29 PM
Post #65 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
In reply to: That's the standard way to belay a leader with an ATC, Dan. Only gumbies keep the rope locked off all the time, unless their partner is moving at a snail's pace. It's the rope-behind-the-butt-all-the-time belayers that you should worry about. They'll short rope you on every move. This is how it should be done (cute tilting of head is optional): http://www.rockclimbing.com/...mp.cgi?Detailed=3810 From this position, she can lock off or feed rope instantly. To dynamically belay, the hands should be kept further from the ATC, but the angle between the ropes is correct. -Jay
I guess I am a gumbie because, I keep the device locked off whenever I am not looking at the climber or feeding a clip. I actually lock the device against the biner, not put my hand behind my butt, and I don't short people
As far as the posed picture of your hottie belayer,
She is belaying a toprope with tension from the looks of it. Her hands are in a bad position, unless she is shuffling a toprope belay. She it to far from the rock, she has a bunch of junk under her feet that she could trip on.
Not a very good example of lead belaying technique.
|
|
|
|
|
sticky_fingers
Jul 23, 2003, 4:36 PM
Post #66 of 118
(7980 views)
Shortcut
Registered: Jun 17, 2003
Posts: 420
|
In reply to: Sticky-fingers If your in a real squeeze chimney you want to hang "all" your gear on a long sling hanging from your belay loop.(lead or second)
that's pretty much how i do it. i was just being brief earlier describing how to rack stuff going up a chimney...outside.
In reply to: ....your much better off not knocking rocks down in the first place.
obviously, but you don't always know what's ahead or if the rock will hold. Look what happened on the Totem? I'm sure no one intended for that to happen....
In reply to: Rock fall usually kills the belayer not the leader, and if a leader thinks a belayer using a gri gri makes him safer I wouldn't want to belay him.
yes....rocks do usually fall towards earth. I haven't seen a whole lot of ripped out flakes turning around and attacking the leader. at least we agree that gravity hates the belayer
seriously though, I'm gonna assume you drive with seat belts (same principle). the reason you do is in the unlikely event you're going too fast to stop your motion by yourself, a seat belt locks up for you. In the unlikely event my belayer can not belay me, i hope my life won't also be in jepordy.
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 4:41 PM
Post #67 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
Tenn-dawg
In reply to: We had a Snarg as the test piece connected to the rope with a draw with BD QS2 biners. A few feet below this was two equalized screws (BD and a Grivel). They were equalized with a single 24" sling and a locked Big Easy was connected to the rope. The biner on the snarg broke, the hanger on the Grivel screw sheared along its long bend, then the big easy locked biner broke! This is three pieces of hardware that broke on one fall.
This is a lead placement configuration. And the anchor didn't fail, the gear itself broke.
Agreed that this isn't an ideal test, but Harmstom is one of the best authorities on rock gear that I have heard of and he contends that a static belay device significanly increases the forces on lead placements.
|
|
|
|
|
tenn_dawg
Jul 23, 2003, 5:25 PM
Post #68 of 118
(7980 views)
Shortcut
Registered: Mar 14, 2002
Posts: 3045
|
In reply to: Tenn-dawg In reply to: We had a Snarg as the test piece connected to the rope with a draw with BD QS2 biners. A few feet below this was two equalized screws (BD and a Grivel). They were equalized with a single 24" sling and a locked Big Easy was connected to the rope. The biner on the snarg broke, the hanger on the Grivel screw sheared along its long bend, then the big easy locked biner broke! This is three pieces of hardware that broke on one fall. This is a lead placement configuration. And the anchor didn't fail, the gear itself broke. Agreed that this isn't an ideal test, but Harmstom is one of the best authorities on rock gear that I have heard of and he contends that a static belay device significanly increases the forces on lead placements.
I agree, it is certain that using a static belay device will increase forces on a lead placement. The question is to the degree of increase (most preferably measured in percent) in a variety of similar situations.
This test would be so easy to do: Simply aquire 3 or 4 ropes for test medium, Set a high anchor with a load measuring device, and lob off some weights. I would preferably use a Human belayer, holding the device in the full locked off position, standing straight up on his feet, and not jumping.
Alternate ropes so the dynamic properties have time to regenerate, and go through a sample set, measuring the loads using a constant weight, drop distance. Switch belay devices, and measure again.
A little math, and you have a definate percentage difference in load felt. A little more time and math, and you could get the standard deviation of both curves and figure out if the difference is statistically significant.
No sweat.
A day would be plenty of time, and If I had the resources avaliable, I would do it on my own. Sadly, I'm absolutely broke, and can't dedicate any funds to this.
Someday though...
Travis
|
|
|
|
|
jt512
Jul 23, 2003, 6:41 PM
Post #69 of 118
(7980 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: As far as the posed picture of your hottie belayer, She is belaying a toprope with tension from the looks of it. Her hands are in a bad position, unless she is shuffling a toprope belay. She it to far from the rock, she has a bunch of junk under her feet that she could trip on. Not a very good example of lead belaying technique.
The picture was not posed, she is belaying a leader, and there is no tension in the rope. As I already stated, I posted the pic to demonstrate what I consider a good angle at which to hold the ropes when belaying a fast climber, not the optimal footwear.
This is the approximate angle at which most experienced sport climbers hold the ropes. Look at pictures of professional sport climbers in magazines. The belayer doesn't have the belay device locked off while the climber is moving. He has the rope in a neutral position -- 45 to 90 degrees apart -- from which he can quickly take in or let out slack. There is no reason to lock off the belay device every time you let out slack. When the leader falls, then you lock off. You do not lose control of the belay, even if caught off guard, in part, because with the ropes at 45 - 90 degrees from each other, the device still provides friction. I have caught innumerable falls this way, as have innumerable other belayers. If you can avoid short roping the climber without leaving too much slack in the rope and locking the device off constantly, then the only disadvantage you have is that you can't let rope run through the device to dynamically belay -- a minimal disadvantage on most sport climbs because you have the option of jumping, which is what most of us do, anyway.
-Jay
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 7:02 PM
Post #70 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
Jay,
Agreed that the angle between her hands looks fine.
My comment about the hand in front of the device was directed at people who keep both strands closer to parallel, not 45 to 90.
btw, when I "lock off" the device I do it with the non-break hand, ie snug it against the biner. This helps insure that I don't get caught off guard. A confusing different application of the word, but still the best I can think of. A good example of how the written word doesn't cover all the bases.
For myself on lead in particular, the rope in the pic would be tension.
|
|
|
|
|
jt512
Jul 23, 2003, 7:09 PM
Post #71 of 118
(7980 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: This test would be so easy to do: Simply aquire 3 or 4 ropes for test medium, Set a high anchor with a load measuring device, and lob off some weights. I would preferably use a Human belayer, holding the device in the full locked off position, standing straight up on his feet, and not jumping. Alternate ropes so the dynamic properties have time to regenerate, and go through a sample set, measuring the loads using a constant weight, drop distance. Switch belay devices, and measure again. Travis
I'm pretty sure such tests have been done; otherwise, where would the specific numbers quoted for the braking forces of various devices have come from? Once again, Clyde Soles would probably know. He wrote an article for R and I in which he quoted these figures.
As far as the specifics of the test, it would be a little less straightforward than you describe. Conventional belay devices act as grip strength magnifiers; their braking force is thus a function of how strong the belayer is. Also the belayer's body size and position will affect the impact forces. Rope diameter and, of course, construction, also affect impact forces. For purposes of compaisons among belay devices these factors can be largely controlled by using the same belayer and similar ropes for each belay device, at the expense of generalizability. It would be unwise to use the same rope for more than one test, though, even allowing for recovery time, because it cannot be reasonably assumed that the rope would fully recover.
-Jay
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 7:44 PM
Post #72 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
In reply to: This test would be so easy to do: Simply aquire 3 or 4 ropes for test medium, Set a high anchor with a load measuring device, and lob off some weights. I would preferably use a Human belayer, holding the device in the full locked off position, standing straight up on his feet, and not jumping. Alternate ropes so the dynamic properties have time to regenerate, and go through a sample set, measuring the loads using a constant weight, drop distance. Switch belay devices, and measure again. Travis
I found a reference to a test that rei did and they used a clutch mechanism for the belayers hand set at 50lbs.(googled rec.climbing)
On the clarification side, I don't think using a gri gri would be unsafe. But it probably is less ideal then an atc where impact forces are concerned.
|
|
|
|
|
alpnclmbr1
Jul 23, 2003, 8:13 PM
Post #73 of 118
(7980 views)
Shortcut
Registered: Dec 10, 2002
Posts: 3060
|
Full text at
http://www.somat.com/applications/articles/rei.htm
(snip)
Because REI wanted to evaluate the performance of different belaying devices to establish which ones were best for various climbing situations, they needed real-world load data. They designed a series of tests that would measure the performance of the belaying devices by quantifying two factors. One was the peak load experienced by the protection. The other was average load which tells how soft or how firm the catch is.
The test is performed by dropping a steel plate from a modified UIAA drop tower which is two stories tall. The letters UIAA stand for the French alpine organization which standardized the drop test. To simulate the climber in the test, the engineers use an 80 kg (176 pound) steel plate. This plate has a Teflon block at each corner and when it is dropped to simulate a fall, it slides down the aluminum rails mounted into the timbers which form the tower. The rope is attached to the plate and then goes through the carabiner and the belay device. From there it runs through the brake hand and then through two spring loaded plates that provide friction on the rope that simulates the belayers' grip hand. This plate holds the rope with what the engineers determined was an average grip force--25 pounds. One load cell is attached to the protection and the other to the friction device that represents the belayer. They initially tried to attach a third load cell to the plate representing the climber but it moved so much during the drop that it broke the wires. Since the Model 2100 permits on-line data analysis, the load on the climber is derived by combining the data from the other two measurement channels.
(snip)
The test findings confirmed what experienced climbers had suspected but never had actual load values to prove. For example, the cam lock static belay device put the greatest load on the protection--2215 pounds. The load on the belayer in this test was 839 pounds and the load on the climber was 1382 pounds. Another type of belay device called the Trango Pyramid was expected to have a light catch. It did, expelling nearly 30 inches of a 10.5 mm rope. The maximum load on the protection with this device was 927 pounds. The loads on the belayer and climber were 265 and 662, respectively. One of firmest catches from a dynamic belaying device came from the HB Bigger Brake which put a load of 392 pounds on the belayer, 835 pounds on the climber, and 1227 on the protection.
(snip)
I am back to thinking grigri's are bad for trad.
|
|
|
|
|
ambler
Jul 23, 2003, 9:17 PM
Post #74 of 118
(7980 views)
Shortcut
Registered: Jul 27, 2002
Posts: 1690
|
That's quite a difference, around double the force on the protection from a static Gri-gri belay (or Muntner?). Reinforces my own prejudice that for trad free climbs, at least, ATCs and the like are the best way to go.
The other striking thing in this thread is the note about carabiners breaking, but not the rope which was theoretically weaker. There has been much discussion on these forums about the strength of various knots in rope and webbing, but I can't offhand recall reports of accidents where ropes or slings broke (cut or came untied, yes). On the other hand I've broken two carabiners in falls myself, and heard of many others. It seems like the metal gear in the system often might be more fragile, in practice, than its rated strength would suggest.
Reinforces the advice I think Brutus has trademarked, that falling can be a Big Deal.
|
|
|
|
|
tenn_dawg
Jul 24, 2003, 1:04 AM
Post #75 of 118
(7980 views)
Shortcut
Registered: Mar 14, 2002
Posts: 3045
|
In reply to: I'm pretty sure such tests have been done; otherwise, where would the specific numbers quoted for the braking forces of various devices have come from?
That test was done by hooking a puller to the rope and pulling directly against the device, and observing the load at which the rope began to slip.
It is related, but still not a good indicator of the force felt on the lead piece for reasons I've stated above, including the duration of >500lbs force exerted at the belay device, and the resulting distance of rope slip.
The two are related, but I've never seen how much this really affects the load force, and duration felt at the lead placement. And this is really the key issue here. Not the force at which the device allows the rope to begin slipping.
Travis
|
|
|
|
|
|
