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tanner
Feb 26, 2003, 5:09 AM
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At work my boss came up and showed my how to make a "self equalizing ancher" using the sliding X. I explaind that it was safer to tie an overhand knot to equalize then the pull down "sliding x" he was showing me. Am I right in that the sliding x has little use in climbing exept equalizing pro on a climb when its imposable to tie an overhand knot. also that it can be dangerous because if one ancher point blows the sliding action can blow the other one.
I was worried because he was going aroud teaching this to people.
What do you think sliding x safe or unsafe
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fritzski
Feb 26, 2003, 5:40 AM
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I sometimes like to use the sliding X to create a top rope anchor. If one of the two anchors fails it works well, but it's weakness is that if the webbing fails its a gonner. Because of that, I always use two runners together - both Xed.
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swohletz
Feb 26, 2003, 5:48 AM
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A sliding X can be helpful for toprope when you anticipate climbers going off route some to try different approaches...then no matter where they go the system stays equalized and falls are smoother, even when swinging happens. I work with a program where we set up topropes and we use sliding X's a lot and just back it up with a second piece of webbing that is X'ed as well as a backup. Sometimes when setting an anchor I'll initially make an X to equalize it and then put an overhand in the end like you said to make it redundant....
climb on
susan
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tanner
Feb 26, 2003, 5:49 AM
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Thats correct the webbing could fail using two is better. But if one ancher blows it could shock load the system and blow the other ancher. I wonder if that is a real risk?
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jsj42
Feb 26, 2003, 6:08 AM
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Well, the sliding X is the subject of some debate, but I would have to argue against the blanket recommendation of it's use (sorry Susan!).
The Sliding X should ONLY be used in a situation where BOTH anchors are absolutely bombproof. The reason is that if one anchor fails, as the X extends to full length it will staticly shock-load the other anchor - a very bad situation.
The advantage of the Sliding X is that, as long as both pieces remain in place, it will equalize and allow for different angles of force. For this reason I used to use it exclusively, but now I almost NEVER use it - the risk is two great if one piece fails. A much better idea is to tie a knot in the sling, so that if one piece fails the other is not shockloaded. If varying vectors are a concern, directionals can be incorporated.
Some climbers assert that a Sliding X is still useful when there are two marginal pieces (neither of which would hold a fall independently). However, these can still be equalized using knots or other methods.
For more info/a different explanation, there is footnote on the ASCA's home page (http://www.safeclimbing.org/info.html). I believe they call it the "death X".
Josh
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petsfed
Feb 26, 2003, 6:16 AM
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The idea is, if both peices are absolutely bomber, why equalize, as they are both strong enough to hold alone. A good use for the sliding x is for equalizing two pieces into one, and then using that as a single peice within a multipiece anchor.
\
-\
-/\ <-Sliding x location
/--\_ <- Power point of anchor
---/
--/
-/
/
Does that make sense?
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swohletz
Feb 26, 2003, 6:17 AM
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Josh is right (you are smarter, I give in)....the program I works for uses this at a site where we have 2-3 bomber anchors that we equalize with sliding x's and back up with a second piece of webbing....we mostly do it to make it easy to learn for staff.
When I set up my own anchors, I use separate pieces of webbing or knotted webbing. I just feel safer.
I have learned something today :)
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tanner
Feb 26, 2003, 6:38 AM
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Josh, that exatly the way I look at things.
I wonder if the sliding x is actualy dangerous and if anchers have failed because of it?
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caughtinside
Feb 26, 2003, 6:40 AM
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I use two sliding X's as well. People are really concerned about shock loading one bolt if one fails on a bolted toprope, but I think this is unrealistic.
If you're setting it up, you are close enough to inspect the bolts. If they both look sound, the chances of one failing is minimal. If it does fail and the other bolt is shock loaded, this should not be a problem, because if you are using shoulder length slings, you are going to fall 1 foot.
I've taken plenty of lead falls onto one bolt while sport climbing. The force those bolts can hold is impressive. If it can handle me shaking off while trying to clip and falling 30 feet, a one foot 'shock load' will not be a problem.
Plus, I think you get a smoother belay when your anchor moves and equalizes freely.
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rrrADAM
Feb 26, 2003, 12:36 PM
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I use it to double up before a runout, or sketchy crux while on lead. I use use a shoulder length attached to each piece with a biner, and a locker to the rope.
For a picture of this, look at the new Gear Guide issue of Climbing, as there is a chick leading a .12 on the cover, with this set up on 2 stoppers.
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piton
Feb 26, 2003, 2:09 PM
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i use the sliding x exactly the way rradam explained, but not on scethcy climbs
also when i opposition pro i tend to use the sliding x, but never as a anchor
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sycamore
Feb 26, 2003, 2:56 PM
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FWIW, I couldn't help but notice that under belaying/rigging a belay at the Petzl website, they recommend a sliding x with an overhand knot to minimize shock load.
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jhwnewengland
Feb 26, 2003, 3:52 PM
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sycamore is referring to here:
http://www.petzl.com/statique/sport/ENG/tech/html/belay1.html
I don't like it. The overhand is on one side only, and I don't really know why it's there. Yes, the shock loading would be minimized if one of those pins failed, but what if the other failed? I'd only use the sliding X on an anchor if the two anchor points were 3/8" bolts that I completely trusted, or on two pieces of the anchor that act as one (i.e. not as the power point of the anchor).
In toproping, you're not going to generate TOO much force, so it would be more acceptable to me. I still wouldn't use it, though.
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cracklover
Feb 26, 2003, 5:23 PM
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Yes of course it has useful applications. The main point is that as far as I know it is the only way to self-equalize two points of protection. Sometimes that's more important than the potential downsides.
GO
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mountainmonkey
Feb 26, 2003, 5:28 PM
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from belay guru:
In reply to: i cant beleive so many climbers out there don't understand the SERNE priciple to anchors and give advice about the sliding x, magic x, etc. and do not know how to rig it. the sliding x provides the most SERNE anchor in the quiver.
OH REALLY!
What part of No Extension do you truely understand?
There are ways to minimize the extension, i.e. overhand knots, but they weaken the webbing.
The sliding x provides a multidirectional, equilized anchor that will have extension if one part fails. Without two slings, it is not Redundant. For Solid anchors, you do not need perfect equilization.
No Extension is imperative for multipitch anchors where a belay will be tied in short to the anchor. For toprope anchors, there is enough rope to absorb any impact force from extension should one piece blow.
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dingus
Feb 26, 2003, 5:43 PM
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OK, here's the real deal...
Sliding X for lead pro when you need two pieces cause one or more likely both is marginal and/or directional. Equalize using sliding X. Shock load isn't a huge issue cause if one blows they're both going anyway. THAT'S WHY YOU X'D THEM IN THE FIRST PLACE! If they're really bad you can top if off with a screamer. And if you just have to minimize the shock load risk and are carrying the gargantuan racks you kids seem to tote these days, add an additional sling from each piece down to the X... slightly longer so as to allow the X to do it's job. Whew! If you do that, like, why bother with the X though???
Sliding X's can also be used in a belay arrangement, in place of a cordelette. Cordelettes have their place of course, on big walls with complicated belays, in the hands of beginners, avoiding cluster flucks, etc. But when multi-pitching with an absolute minimum of gear (one of my joys in life), a sliding X can be welcome addition to a belay. Here's how I might use it (every single belay, by the way, bolted or not, is different and 'one size fits all' answers are for morons)...
A 3 piece anchor is built. At least one of these is set to hold an upward pull. Sliding X on two of the pieces and either another runner or more likely the lead rope tied into one of those and the 3rd piece with a minimum of extenstion ( clove hitch the knot nearest my harness, 8-on-a-bight the other). The lead rope achieves the minimun extension. It also accomplished redundancy. The sliding X does the equalization especially with respect to the upward pull apsect.
I don't use it all the time. Most times I have 3 bomber pieces and will knot the lead rope 3 times and back the enterprise up with a sling or a daisy clip in. Simplicity itself.
Shock loading should be a concern, something you think about and consider as you build your anchor. But you don't need to swear off this very useful sling technique because of it. Or better said, I feel no such need. You do whatever your heart dictates. This is not advice and doing as I do could get you killed. Or not.
DMT
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sycamore
Feb 26, 2003, 7:34 PM
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Here's when I use it. On topropes where the 'power point' carabiners have to be farther off the edge than I can reach, perhaps so it is below a sharp edge or something. Say I have a big tree and a big horn, both slung with tubular. If I connect these together with two x'ed slings, and clip in the rope, I can then toss the whole contraption down and know that it'll equalize, instead of tossing it down, yelling to my partner "does it look good?", "no, the left webbing needs to be a little shorter", pulling it all up, retying, throwing it down, ad infinitum.
And I must admit, I've used it for two bolt anchors too. I've pretty much stopped, but I think the 'shock load' argument has been blown out of proportion (for a two-bolt toprope anchor):
"Poor comparison: Your climbing rope is dynamic. Anchor webbing is static."
A valid point, but say a bolt blows and your carabiner slips down a foot or so, 'shock loading' the second bolt. People seem to forget that there is still a dynamic rope in the equation--yes, webbing is static, but even in a shock loading scenario, there will be a significant amount of rope stretch. A 'shock load' scenario on toprope with a bolted anchor will not produce anywhere near the force on the second, remaining bolt as a long lead fall.
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fitz
Feb 26, 2003, 10:30 PM
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I've used the sliding X to combine pieces on trad lead pretty much as RRRAdam describes. However, if I have good feet, I'll usually put one or two overhands in the double length runner to minimize shock loading. If the stance is sketchy, I clip a folded, second runner back to the bottom piece. If the stance is really sketchy, I just try not to fall...
I can't recall ever using a sliding knot in a toprope or belay anchor. But, I generally try to keep things simple.
Whoever boasted about the obvious strengths of one bolt and assured us that a little shock loading was no problem. I suggest you exploit that fact. Trim your rack down to one biner (they are amazingly strong also). After all, 1' of shock loading means you are equalizing normally spaced anchor bolts with a 2' runner. Since the concept of load multiplication alludes you, you are probably better off just picking one and hanging your life on it. With luck, you might even win a Darwin award.
As for Belay Guru, I'd have to second the criticism above. Please carefully re-read "How to Rock Climb" before explaining Largo's version of RENE to others. By itself, a sliding X is an E.
-jjf
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rrrADAM
Feb 28, 2003, 2:27 PM
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Now read this...
The sliding X is to multidirectional equalize two pieces. If you tie an overhand in it, it is no longer multidirectional. You have defeated the purpose.
Regarding shockloading... If you have a sliding X on two pieces, ytou shockload both pieces with only 1/2 the force. If one fails, the piece left will only be shockloaded by the length of sling used. (This is much less force that the original fall, since it was higher, and much of the force was absorbed by the 2 pieces before one failed.) Do the math... You are better off.
Think of it this way... If you have the choice of putting 3 sketchy pieces one after the other, individually, and peel from 15 feet above, chances are you will pull all 3. If you make 2 sketchy pieces equalized with a sliding X, you have in effect made the placement much more solid, and redundant since you have 2. I would much rather fall on 2 sketchy pieces equalized with the sliding X, that 3 sketchy pieces placed in series.
If you prefer 3 sketchy pieces used in series, then do so. However, I will use the sliding X.
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micronut
Feb 28, 2003, 2:48 PM
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It's possible to use the sliding x on more than two pieces.
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piton
Feb 28, 2003, 4:22 PM
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i thought with the sliding x the pull has a chance to change direction? so if you have a shallow placement the pull force can be loaded onto that shallow piece. i only use this on horzontals with good gear. when i opose on a verticals i tend to hitch the 2 pieces together.
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rrrADAM
Feb 28, 2003, 4:41 PM
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Good point 'micro', I have done it with 3 on only two occasions though.
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jt512
Feb 28, 2003, 6:48 PM
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In reply to: Regarding shockloading... If you have a sliding X on two pieces, ytou shockload both pieces with only 1/2 the force. If one fails, the piece left will only be shockloaded by the length of sling used. (This is much less force that the original fall, since it was higher, and much of the force was absorbed by the 2 pieces before one failed.) Do the math... You are better off.
I don't understand the above reasoning at all. The amount of force on the second piece depends on when during the fall the first piece fails. If the first piece fails immediately, then the second piece won't really be shock loaded; however, it will feel the full force of the fall, since the system has not yet absorbed any of the energy from the fall. A potentially more serious situation is when the first piece fails at the peak impact force of the fall. In this case, the system has already absorbed as much of the energy of the fall as possible, and the remaining piece is shock loaded; that is, it is hit with a sudden increase in force, with no dynamics left in the system to absorb any energy.
In reply to: Think of it this way... If you have the choice of putting 3 sketchy pieces one after the other, individually, and peel from 15 feet above, chances are you will pull all 3. If you make 2 sketchy pieces equalized with a sliding X, you have in effect made the placement much more solid, and redundant since you have 2. I would much rather fall on 2 sketchy pieces equalized with the sliding X, that 3 sketchy pieces placed in series.
There is more than one way to equalize two sketchy pieces. Which way you choose should depend on just how sketchy the pieces are. The sliding X provides optimal equalization at the expense of "no extension." This trade-off is only favorable if the pieces are so sketchy that both would likely fail if not perfectly equalized. In this case, you don't care about extension because the placements are so poor that, regardless of how they are equalized, if one piece were to fail, the other would, too.
A more common scenario is that you want to equalize two pieces that are less than ideal, but not as bad as above. You want the pieces to share the load, but if one piece fails, the other will still probably hold, provided it isn’t shock loaded. In this case, “no extension” is more important than perfect equalization, and you should equalize the pieces statically. The best way I know of to do this is to tie a double clove hitch in a sewn runner; that is, to tie a single clove hitch in both strands of the runner. This forms three points of attachment in the runner: the hitch itself plus two loops. The clove hitch is put on one of the pieces to be equalized, and one of the loops is attached to the other piece. The rope is clipped into the remaining loop. Adjust the clove hitch as needed to optimize the equalization.
This method is superior to using two clove hitches in a single strand of a sewn runner to statically equalize two pieces. It has two advantages: One, it is simpler to set up, since there is only one knot; and, two, it is stronger, since the sling is doubled.
-Jay
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rrrADAM
Feb 28, 2003, 7:32 PM
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In reply to: A potentially more serious situation is when the first piece fails at the peak impact force of the fall.
If it is at peak impact force, then it has already absorbed much of the force up to that point. If one fails, it will see less load... Get it.
Also if it fails imediately when on the low end, then it was not sketchy, it was not worth placing at all.
The point of the sliding X is that it multidirectionally equalizes, and is relatively quick to set while on lead, rather than having to tie knots and such... This is hard to do when leading at your level, right ???
Jay, I know you are not a fan of this, so don't use it.
Again, you can see this system being used on the current cover of the Climbing Gear Guide. She, the climber, has the exact system I explained on page 1, conected to two stoppers while leading. And it's a Trad.12, so I don't think loitering around to tie knots would help, and it would also take out the self equalizing properties.
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