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aikibujin
Jan 27, 2005, 2:19 AM
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In reply to: In sport you don't really need to worry about the line of the rope because it's been done for you. With that said, when you fall, do all of the draws between the top and bottom get pulled by the rope or do they hang loose? THey get pulled out, Because the rope is in a straight line. Would the top draw have more force put on it if these "middle" draws are there or if they aren't. If there is only one draw to fall on, it will have more force put on it then if you are a dozen draws up.
I am not a physist, but I did read a physics textbook once... or was it an Spanish textbook? Anyway, here's my $0.02: suppose if all the bolts (or the pieces of pro) runs in a straight vertical line, and your belayer is standing right next to the rock directly under the first bolt (or piece). Then when you fall, all the draws except the very top one will stay loose. But of course, that's an exceptional case.
When you fall, if the belay is totally static with zero slip (happens only in theory), the rope slip through the biners a little from rope stretch, but how much energy this absorbs is debatable. Especially considering the friction in the biners effectively reduce the amount of rope out to absorb more energy.
If the belay is dynamic, then all the added friction in the system MAY actually reduce a considerable amount of energy. However, this is also debatable, and weighing the benefit of reduced impact force with the risk of pulling out gear in a non-anticipated direction of pull, I think the risk outweighs the benefit.
But that's just my opinion.
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cracklover
Jan 27, 2005, 4:13 AM
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In reply to: Would the top draw have more force put on it if these "middle" draws are there or if they aren't. If there is only one draw to fall on, it will have more force put on it then if you are a dozen draws up. That is all I was saying.
I understand what you are saying perfectly well. The problem is that what you are saying is dead wrong. When the rope runs directly from the top piece to the belayer, the entire rope is available to absorb the force of a fall. The more friction in the system between the top piece and the belayer, the less the rope towards the bottom will stretch. The less the rope stretches, the shorter the stopping distance. The shorter the stopping distance, the higher the peak force on the top piece. For some reason you are refusing to believe this fact.
There are test results available online if you don't believe me.
GO
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jakedatc
Jan 27, 2005, 4:23 AM
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oo sport in the trad forum... myself the sport weenie Loves this...
Not all sport climbs are bolted in a straight line.. some very much not...and not all the draws will be tight all the time..
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johnnord
Jan 27, 2005, 5:11 AM
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In reply to: In reply to: Would the top draw have more force put on it if these "middle" draws are there or if they aren't. If there is only one draw to fall on, it will have more force put on it then if you are a dozen draws up. That is all I was saying. I understand what you are saying perfectly well. The problem is that what you are saying is dead wrong. When the rope runs directly from the top piece to the belayer, the entire rope is available to absorb the force of a fall. The more friction in the system between the top piece and the belayer, the less the rope towards the bottom will stretch. The less the rope stretches, the shorter the stopping distance. The shorter the stopping distance, the higher the peak force on the top piece. For some reason you are refusing to believe this fact. There are test results available online if you don't believe me. GO
I need some help with this one.
Assume two climbs. The first climb has one piece 50' up. The rope absorbs the force of the fall and the top piece is subjected to "x" amout of force. In the second climb there is on piece between the top piece and the belayer. In the event of a fall the rope and the intermediate piece both the absorb the force of fall. Why is the amount of force on the top anchor greater than "x"? The reason the stopping distance (function of rope stretch) is less is because the force on the rope has been reduced (albeit minimally) by the intermediate piece. I'll check with my physicist friend tomorrow and ask him. (IMHO I don't thing the amout of friction added by intermediate pieces on a relatively vertical climb amounts to much)
Also, if there are intermediate pieces acting on the rope, doesn't that mean that there is more rope out and therefore more force being absorbed by the rope?
Also, does the rope stretch differently at the bottom as you suggest, or does the rope spread the force over the entire length of the rope?
Can you give the URL for the online source you refer to?
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david.yount
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Jan 27, 2005, 5:20 AM
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In reply to: In reply to: Would the top draw have more force put on it if these "middle" draws are there or if they aren't. If there is only one draw to fall on, it will have more force put on it then if you are a dozen draws up. That is all I was saying. I understand what you are saying perfectly well. The problem is that what you are saying is dead wrong. When the rope runs directly from the top piece to the belayer, the entire rope is available to absorb the force of a fall. The more friction in the system between the top piece and the belayer, the less the rope towards the bottom will stretch. The less the rope stretches, the shorter the stopping distance. The shorter the stopping distance, the higher the peak force on the top piece. For some reason you are refusing to believe this fact. There are test results available online if you don't believe me. GO
yep, what he said.
i've never watched a climbing video. with a title like "Masters" i wonder if this video featured a few clips of 70's climbers? it was common to use a single biner to clip the rope to the placement. often two biners were used. slings weren't common.
but now since nylon webbing is cheap and plentiful (and spectra/dyneema is truly delightful) most placements are improved with a runner.
ideally the lead climbing rope should run in a straight line. long runners help to keep the rope line straight, even when the climbing line is not straight. i usually prefer to use a longer runner to keep my rope straight and accept the fact that longer a longer runner will increase my fall if i were to fall on that longer runner.
if the rope does not experience any zig zags then the entire belay length can help to absorb falling force, making the maximum load at the top piece as small as can be. reducing the load at the top piece in case of a fall is certainly a priority goal for me.
if the rope does not experience any zig zags then placements will be best protected from jiggling forces from rope movement. i make very careful placements and i don't want them to move.
if the rope does not experience any zig zags then rope drag is minimized and i'm having a more enjoyable time lead climbing.
david yount.
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shutupandclimb
Jan 27, 2005, 5:27 AM
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You are saying that a short runner on a lower piece is pointing straight out in a fall. But if it were to take some force off the belayer it would have to be taking an upward pull.
Thinking in vectors, pulling a piece close to straight out, the downward pull from the piece is going to be very small compared to the outward pull. For any noticable amount of energy absorbed by that piece it would have to take an upward pull.
The energy absorbed by the top piece will be the same with either a short draw or long runner, but with a long runner it is absorbed by the belayer instead of the lower pieces. Get some runners and a soft catch.
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tradklime
Jan 27, 2005, 3:33 PM
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For those who are having trouble with this, here's the deal...
You want as little friction in the system as possible so that the rope can do it's job. In simplistic terms, the ropes job is absorbing the force of a fall. Friction is introduced by the rope zig-zaging, running tight over buldges, etc. In a perfect world, in a fall, the rope would only be tight against the biner attached to the piece catching the fall. The rope should run freely through the other pieces of protection, if it does not, you are isolating (at least partially) portions of the rope that won't be able to do its job. The more rope available to absorb force, the better.
Another benefit of reducing friction is reducing the amount of drag on the climber as they move upward.
Sorry to repeat what others have said, but hopefully this will put the questions to rest.
As a side note, this is of course over simplified because you may want some sort of redirection at the first piece to avoid zippering. But that's another topic.
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cracklover
Jan 27, 2005, 3:43 PM
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In reply to: In reply to: In reply to: Would the top draw have more force put on it if these "middle" draws are there or if they aren't. If there is only one draw to fall on, it will have more force put on it then if you are a dozen draws up. That is all I was saying. I understand what you are saying perfectly well. The problem is that what you are saying is dead wrong. When the rope runs directly from the top piece to the belayer, the entire rope is available to absorb the force of a fall. The more friction in the system between the top piece and the belayer, the less the rope towards the bottom will stretch. The less the rope stretches, the shorter the stopping distance. The shorter the stopping distance, the higher the peak force on the top piece. For some reason you are refusing to believe this fact. There are test results available online if you don't believe me. GO I need some help with this one.
Okay, I'll do my best.
In reply to: Assume two climbs. The first climb has one piece 50' up. The rope absorbs the force of the fall and the top piece is subjected to "x" amout of force. In the second climb there is on piece between the top piece and the belayer. In the event of a fall the rope and the intermediate piece both the absorb the force of fall.
The top piece and the intermediate piece do "absorb" some energy (more specifically they change energy from kinetic to heat through friction). But a larger issue comes from the fact that those biners are reducing the amount the rope can stretch. Let's take an extreme case. Lets say that you put a munter hitch around your top piece. Do you see that now any fall would turn into something approximating a factor two fall? So as any biners in the system add friction, you come closer to this absolute.
In reply to: Why is the amount of force on the top anchor greater than "x"? The reason the stopping distance (function of rope stretch) is less is because the force on the rope has been reduced (albeit minimally) by the intermediate piece. I'll check with my physicist friend tomorrow and ask him. (IMHO I don't thing the amout of friction added by intermediate pieces on a relatively vertical climb amounts to much)
It's not how vertical the climb is that matters, but the amount of friction in the system, due to either zig-zagged rope through biners, or around overhangs or corners.
In reply to: Also, if there are intermediate pieces acting on the rope, doesn't that mean that there is more rope out and therefore more force being absorbed by the rope?
Good question. As it turns out, the extra rope cannot absorb any extra force, because of the extra friction. If the biners were all frictionless pulleys, I suspect you'd be right, though I haven't thought that one through.
In reply to: Also, does the rope stretch differently at the bottom as you suggest, or does the rope spread the force over the entire length of the rope?
Um, you're asking me?
In reply to: Can you give the URL for the online source you refer to?
I cannot find one right now, but I noticed that since the research came out, the petzl fall simulator added an option to put in zig-zagged protection, so you can see how that impacts the forces on your protection. Here is a link to their site. (Be patient, it loads quite slowly.)
Hope that's helpful.
GO
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sarcat
Jan 27, 2005, 3:55 PM
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VERY informative thread. Thanks to david.yount. excellent post.
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aikibujin
Jan 27, 2005, 4:03 PM
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In reply to: a fall. The more friction in the system between the top piece and the belayer, the less the rope towards the bottom will stretch. The less the rope stretches, the shorter the stopping distance. The shorter the stopping distance, the higher the peak force on the top piece. There are test results available online if you don't believe me.
In reply to: I cannot find one right now, but I noticed that since the research came out, the petzl fall simulator added an option to put in zig-zagged protection, so you can see how that impacts the forces on your
Here is one web site that I've found that explains this: www.impact-force.info, it is created by Beal Ropes. It talks about this phenomenon in terms of theoretical fall factor vs actual fall factor.
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cracklover
Jan 27, 2005, 4:24 PM
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In reply to: Here is one web site that I've found that explains this: www.impact-force.info, it is created by Beal Ropes. It talks about this phenomenon in terms of theoretical fall factor vs actual fall factor.
Yes, that's quite nice, thanks. There appears to be a mistake in the single-rope drawing on page 5, though. I believe the left-hand of the two drawings is supposed to show a rope without extended runners, like the left-hand of the two drawings in figure 2 (the half-rope illustration).
GO
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blueeyedclimber
Jan 27, 2005, 5:07 PM
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OK, Gabe, I understand now. Although, I think my thinking was correct, I was not factoring in the loss of rope stretch which I guess trumps my point. None of the posts until yours actually dealt with what i was saying, though. Just so i am clear, are you saying that putting more pieces in could actually increase the force on your top piece? Unless of course, the rope is in a perfectly straight line from your belayer to the top piece.
Josh
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dirtineye
Jan 27, 2005, 5:21 PM
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Unbelieveable.
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caughtinside
Jan 27, 2005, 5:23 PM
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In reply to: Unbelieveable. |
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blueeyedclimber
Jan 27, 2005, 5:27 PM
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In reply to: Unbelieveable.
Back at ya! :roll:
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dirtineye
Jan 27, 2005, 5:37 PM
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The main issue is not the outward pull helping or not helping to absorb fAll force , or the rope stretch, although these things are pertinent, rather, it is the PULLING OF PIECES that could lead to death or injury.
I know people that have hit the ground because they did what you think is correct.
I've seen gear shift, lift and walk in or out because of people doing what you think is correct.
You don't have to believe any of us, you can read about proper gear sling extension in a number of good climbing books.
For your own safety, drop this goofy idea and avoid rope drag as much as possible.
And for the person who thinks a cam will not walk out of a crack and fail, all it takes is a cam on a short sling in a crack that gets wider to the rear and a little drag for that cam to walk in and fall out the bottom. This has happened to a friend of mine. There are other situations where a cam can walk to failure as well.
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blueeyedclimber
Jan 27, 2005, 5:49 PM
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In reply to: The main issue is not the outward pull helping or not helping to absorb fAll force , or the rope stretch, although these things are pertinent, rather, it is the PULLING OF PIECES that could lead to death or injury. I know people that have hit the ground because they did what you think is correct. I've seen gear shift, lift and walk in or out because of people doing what you think is correct. You don't have to believe any of us, you can read about proper gear sling extension in a number of good climbing books. For your own safety, drop this goofy idea and avoid rope drag as much as possible. And for the person who thinks a cam will not walk out of a crack and fail, all it takes is a cam on a short sling in a crack that gets wider to the rear and a little drag for that cam to walk in and fall out the bottom. This has happened to a friend of mine. There are other situations where a cam can walk to failure as well.
Are you just trying to get the last word in? I wasn't talking about rope drag. Everything you are saying right now, I AGREE, and let's leave it at that.
Josh
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cracklover
Jan 27, 2005, 6:16 PM
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In reply to: Just so i am clear, are you saying that putting more pieces in could actually increase the force on your top piece? Unless of course, the rope is in a perfectly straight line from your belayer to the top piece. Josh
Yes. Of course this can be mitigated by proper length slings. Or, for pitches that really wander, double rope technique. And as dirt is so fond of mentioning (and david.yount gave excellent examples of), this has many other important ramifications.
If you're curious to see how the force on your top piece might meet or exceed the rating of that gear in practice, go to the petzl fall simulator link I referenced above. As I mentioned, it now has a parameter that will allow you to simulate a zig-zagged rope.
GO
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piton
Jan 27, 2005, 6:17 PM
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oppose you first placement and make the belayer stands close to wall, not 10 ft back. this will help limit you outward
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healyje
Jan 28, 2005, 10:15 AM
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In reply to: oppose you first placement and make the belayer stands close to wall, not 10 ft back. this will help limit you outward [pull]
Just to be very clear here - Piton is giving you good advice here, but I want to make sure it is understood that the advice has two parts that prevent different problems.
The first is a solution to help prevent zippering your line of pro (e.g. limit outward pull on pieces above the first piece) the statement above should probably simply read:
In reply to: oppose you first placement, this will help limit you outward [pull]
The second has more to do with how much load is being applied to that first omni-directional piece that is preventing the line from zippering. That part of the statement is:
In reply to: ...and make the belayer stands close to wall, not 10 ft back.[pull]
Again, the point here is to reduce the load on that first critical piece that is preventing the line from zippering. A second benefit of belaying close to that first piece is that in the event of a high force fall you, as a belayer won't get drug towards the wall at a fast rate with the climber falling that much more as you come into the wall.
For that matter, even if you are quite close to the wall as a belayer, if your stance isn't well braced I've seen belayers slammed into a wall 2 feet away so hard their hands untensioned on the rope resulting in both a bad fall for the leader and 2nd / 3rd degree burns for the belayer from the rope screaming through their hands. Never underestimate this inward dynamic.
Again, the whole point of putting in that first omni-directional piece is to prevent zippering - if you then stand back from it any real distance you are now jeapardizing that critical placement and the whole line of pro. You put it at risk both by the increased load on it and due to the fact that the line will attempt to zipper if the first placement fails while you're way back. So make sure that first piece is bombers and stick close to it in a solid stance that anticipates a good solid yank straight in towards it.
And Josh, dirtineye isn't simply trying to get in a last word, he's actually just trying to make sure you understand the whole concept clearly after all this winding discussion. He's doing that because he knows how important it is to have an excruciatingly clear understanding of the desired lead mechanics which are:
a) First piece off the belay is omni-directionally bomber
b) All subsequent pieces are slinged appropriately or put in opposition to either eliminate or minimize [the] rope pull on the piece as you climb past it.
[Note: If the line of pro is still going to zig-zag badly then you need to switch to a two-rope lead to elminate the zig-zagging (two-rope leading requires advanced belaying skills and technique).]
c) The "perfect" mechanical scenario is a straightline for the rope in a fall such that only the last piece, first piece, and belay device carry the load while all intermediary pieces (and slings) remain untensioned and unloaded.
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cantbuymefriends
Jan 28, 2005, 1:39 PM
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In reply to: Are you just trying to get the last word in? I wasn't talking about rope drag. Everything you are saying right now, I AGREE, and let's leave it at that. Josh
I think he has every dang right in the world to "just" try to get the last word in! Just to make it perfectly clear to everybody that what you have stubbornly stated throughout this thread is not just wrong, it's also PLAIN EFFIN' DEADLY DANGEROUS!!!
If someone actually listened to what you said, and where to pull a top piece and deck because of the increased rope drag, what would you say?
"Oh, rope stretch? Sorry, didn't think of that! But besides that I think my thinking was correct."
In reply to: Just so i am clear, are you saying that putting more pieces in could actually increase the force on your top piece?
In one word: YES! (I know it's been said earlier, I just wanted to reinforce it.)
(End of ranting. Sorry, 'bout that. Got a bit carried away by such fundamental misunderstanding of one of the most important pieces of safety principles in climbing...)
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blueeyedclimber
Jan 28, 2005, 3:22 PM
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I am getting the last word in and you'll be happy to know it is me EATING CROW!
A lot of what was brought up I already knew and didn't answer my question so sorry I got upset. I see my obvious error now and it has made me a better(safer) climber. Thank you. Although Gabe was the only polite one, it's only because he knows me and I (bragging a little) am a very likeable guy. I was not trying to bs anyone, just thinking about a concept I thought was correct, while not thinking about some other things.
Once again, I am glad you all spoke up and just so you know I do have common sense and do have a lot of knowledge, but also realize that I have a lot still to learn. I am also on edge because Spring seems so far away.
Thanks, Josh
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hugepedro
Jan 28, 2005, 4:32 PM
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In reply to: Just so i am clear, are you saying that putting more pieces in could actually increase the force on your top piece? Unless of course, the rope is in a perfectly straight line from your belayer to the top piece.
Just so it's clear, it doesn't matter how many pieces you put in. How much rope drag you build into your system does matter.
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dingus
Jan 28, 2005, 4:44 PM
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People have been clipping biners directly to wired nuts since they were invented. People have not been dying in droves as a result. Zippering, rope drag and all other considerations (all worthy and should of course be taken into consideration) aside, there is nothing inherently unsafe about clipping a biner to the nut and dropping the rope into the basket, as long as you are aware of the limitations and work to mitigate them.
Simple as that really.
Me? I pretty much put runners of some kind on every placement unless I feel the extra 2-6 feet of fall distance potential poses a problem. When I do clip directly I tend to set the hell out of the nut (nut tool required for extraction). In fact, and I really don't care if my partner is offended or not, I tend to set the hellouta every nut I place)
Later!
DMT
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