I use the sliding x sometimes and most of my partners use it as well. Once in a while I will tie off one strand to prevent excessive extension.

Yesterday at the Ophir Wall my partner said that he felt it was unsafe. He had read something online that said as much. I found the article he was referring to an wondered what the folks here thought?

Thanks,
Brad

http://www.camp4.com/rock/index.php?newsid=451

Back-in-the-day (R), I used the sliding X to equalize opposing nut placements all the time. It's a very easy equalization technique to do with one hand. I rarely make opposing nut placements these days with all the new-fangledy thin camming protection I have. But I still use it extensively to equalize pieces in an anchor. I was aware of the "shock loading" issue, but it never seemed reason to avoid using it. I'd like to see some test data before concluding that this is the "death X." Really? If all the stuff they say is dangerous were really that dangerous, I'd be dead by now.

Edit: No, I did not use the sliding X for one-handed equalization, and it is not easy to do. I used another technique for that, can't remember the name now.

I use a sliding X when putting up top ropes for multiple climbers on sport routes. Based on the link - is this a bad idea?

The linked article cites "too much extension," which I assume is the feared shock loading from the failed side of the X disappearing while the other loop doubles in length. Like NSFOD, I've heard that's the danger, but that's always seemed odd. Severe shock load from dropping an additional foot or so? Not ideal, but hardly the stuff of massive acceleration force. Are the physics more complex than that, or is the criticism just hyper-cautious?

The article doesn't explain, it just declares.

Yes, after reading the article, it seemed unclear...I am assuming a lead fall would generate enough force to render a system failure...I rarely use a sliding x while leading, but when I do it usually links to less ideal pieces into a greater system?

Is using the X in any situation cause for concern?

There were studies/testing done in the course of his recent anchors book update that led John Long to do some major rethinking of the issues of equalization and of shock load on extension. A huge amount of discussion on the subject took place on climbing message boards, but the upshot is that he discovered failure of one piece in a sliding-x anchor causes negligible shock loading on the remaining piece.

That doesn't necessarily mean it's the most desirable solution in a given anchor situation. But if equalization is critical, the sliding-x is viable at least as part of the anchor -- especially in light of Long's other major discovery that the conventional cordellette anchor provides no real equalization at all.

My philosophy for anchors boils down to: "is it good enough [to keep me and my partner alive]?" When the sliding-x is good enough, I'll use it, because often speed and simplicity of set-up is almost as important as having a bomb-proof anchor. (I should add that just two pieces of pro are almost never "good enough;" and when I would use a sliding-x, I'm actually using a Trango Alpine Equalizer, which is essentially a pre-rigged sliding-x.)

JL

As far as the shock loading of piece #2 after piece #1 blows in this system: since the rope is already somewhat loaded and stretched, wouldn't there be more of a "static shock" to piece #2? Or rather, less of a dynamic shock?

My understanding is that if you need the sliding action then use it since it minimizes the load on either piece. Otherwise fix the load angle and prevent the "more static/less dynamic" shock of the remaining piece(s).

Is this way off?

Edit: I just read the above post but I think it is somewhat in line with mine.

Edit2: I frequently feel that I "need" the sliding action because I rarely feel like I can determine exactly the angle of the load and so I'd prefer better equalization to prevent EITHER piece from blowing.

The article reads like an opp edd piece. A triple equalized anchor using two sliding x's is a viable anchor system.

The biggest problem with the picture in the article is that there are no knots where the sling attaches to the two pieces of gear. In its current state, if the sling were to break, then the whole anchor fails. However if you tie a figure eight or equivalent right near the two anchors, you now have two independent strands for the lower carabiner.
If I remember correctly, a recent book has also dispelled the severity of shock loading in this case. If one anchor were to fail, the dynamic properties of a climbing rope would minimize the instantaneous application of force (what I think of shock-loading) on the anchor piece that did not initially fail. The worst case scenario would be if you were clipped in directly to this anchor with a static sling and then fell. This would cause the type of shockloading that might pull an anchor. To make sure this can't happen I try to tie in to the anchor with a bit of my rope end.
I use John Long's equalette for all of my trad anchors (it employs a sliding X) with at least 3 pieces in the anchor and I feel completely comfortable with it. It really is the best option I have seen for equalizing pieces.

Interesting, since I have never seen or heard anyone refer to that "Camp 4" site? Also the sliding X is the AMGA certified way to set up top ropes from bolted anchors. I have never used the sliding X on anything other than bolted anchors or to equalize 2 mediocre pieces while leading. I've always used the cordalette system to equalize a 3 piece anchor.

The Sliding X is not safe at all.

I use it all the time.

I also follow the three rules of setting up belay anchors:

1) Everything must be bomber.
2) Everything must be bomber.
3) Everything must be bomber.
4) Multi-directional with 2 down and equalized with a sliding x and one up tensioned against the X.

If you are worried about extension refer to rule #1.
If you are worried about redundancy, refer to rule #2.
If you are worried about equalization, refer to rule #3.

If you worry about not building a SeRENE anchor like your AMGA anchor course taught you, see rule #4.

Refer to the threads on rc.com about equalized anchors. When Jim (at Sterling) and John Long actually tested anchors with load cells they found two alarming things about the SeRENE anchors he (JL) had been preaching for a long time:

1) The "equalized" anchors are not really equalized. The master knot makes it worse.
2) In a climbing system the amount of additional shock load delivered from a blown anchor leg extending was so low that they were unable to measure it.

BTW, a sliding X does little to equalize either, unless the legs are the same length (It's the dynamic qualities of the material in the EQ rig that cause them to miss out on equalization. The amount of load that a dynamic EQ rig distributes to each leg is inversely proportional to the length of the leg. i.e. a longer leg gets less load.) If you use static material (Dyneema) for your EQ the distribution of the load will be more equitable but nowhere near perfect. I use the sliding X because it's simple and cool.

Fun Fact: The 2 death-by-anchor-failures that have happened in recent history, the Sandias and Taquhiz, both occurred in a SeRENE-cordallette-equalized-master-knotted anchor setup. Both happened because they failed to follow rules #1-4.

Climb safe, be smart, be careful about following rules.
Mal

Edited to add: If you can't meet rules #1-3, go find a different place to belay.

Note: This is a cross post from Supertopo where the same question was asked.

Climbers have been using the sliding knot for a long time, and the potential for shock-loading when using this method is not news. John Long discusses it at length in his "Climbing Anchors" series, (a must-read for aspiring leaders) though he calls it a sliding knot. His sequel "More Climbing Anchors" goes further into the downfalls of the sliding X and makes similar recommmendations regarding it's use.

The danger is that if you use the sliding knot to equalize two pieces of protection, and one piece fails, the sling will essentially double in length and shockload the remaining piece, potentially causing it to fail as well.

Therefore, the camp 4 article suggests using the sliding X only for two situations:

1)Equalizing tenuous pieces in a larger anchor - for instance, two poor nuts in a large natural pro anchor. The nuts are equalized, then the sliding X is equalized with other pieces through a cordelette, webolette, or other non-extending method

2)Equalizing two very tenuous pieces in extreme aid - for instance, a hook and a bashie on A4 terrain.

I agree with these recommendations, only because I can't think of too many other situations where a sliding X is appropriate. I use the sliding X only as described in Scenario 1 above, to equalize two pieces within a larger anchor, that are then further equalized throught a cordelette. I don't use it for anything else.

My main gripe with the sliding X is not only the potential for shockloading, but the complete lack of redundancy. With a sliding X, you are relying on one piece of webbing. There is zero redundancy there. This makes it a poor choice for anything other than the scenarios above, where they are part of a larger system.

For placing nuts in opposition, using clove hitches frequently works as well as a sliding knot.

For equalizing two bolts, probably the most common use of sliding X, I use a quickdraw on each bolt with locking biners. While this does not equalize the load perfectly between the two bolts, it is safer than a sliding X because a) it is redundant and b)there is no potential for shockloading.

The sliding X has it's applications, but there is almost always a better (safer) way. IMHO.

This is a very good point and why I never build my entire anchor around a sliding X linking every piece. I also tie my rope into selected pieces usually too. But, the goal is to never be completely reliant on one piece of gear.

Except, of course, when belaying or rapelling, then I'm just okey-dokey with putting it all on the line with one big locker or one belay device. What is THAT all about???? We all fret over redundancy, but then it seems like everyone always just implicitly trusts that one biner on their harness or that one belay loop.

I have become accustomed to rigging the equalette with the "sliding X" between the two limiter knots that make up the master tie-in point.

John Long's latest book is worth a read as it discusses (at great length) all the various rigging configurations in real world situations.

http://www.camp4.com/rock/index.php?newsid=451

This article is both scary and funny. The claims made in this article are blown way out of proportion. From the article:

----------------------------------------------------------------------
"While the sliding X does equalize the pieces, it assumes that neither could break, since if one does break, there is severe extension in the system - enough that it would likely cause the carabiners to break. Since it assumes neither piece would break, it's a stupid system - if neither would break, there's no need for equalization. If one might break, then there is WAY too much extension. This is why many call it the 'death X.' Instead, use one sling off of each bolt or piece. You can tie one shorter to approximately equalize the pieces if needed."
----------------------------------------------------------------------

I have _never_ heard this called the "death x". True, climbers like to nick-name things with the word death (American-Death Triangle, European-Death Knot) but this is a new one to me.

I have fallen on enough gear/bolts/'biners to know, for an absolute fact, that it is practically impossible to break a 'biner on a TR. Slings, 'biners, ropes, etc. are all built to hold lead falls, including the dreaded Factor 2 fall. By definition, a TR fall is going to have LOTS of rope involved and will be a fall factor well below 1, which means it is a soft fall and will not stress the carabiner.

Unlike the mis-informed author on Camp4, when I use a Sliding X, I am building it because I do think it is possible (although highly unlikely) that an anchor could potentially fail.

The Sliding X is a useful skill for any one rigging a TR and I use it from time to time while leading. That being said, it should only be used by someone who knows what they are doing and knows when it is an appropriate technique and when it is not.

The author of the comment/post on Camp4 is clearly not well educated about the uses and benefits of this technique and based on their preferred technique; I for one would prefer to never climb on one of their anchors.

P.S. - I do not recommend building an anchor composed of a single Sliding X. In an anchor, everything should have some form of back-up / redundancy. When using a Sliding X I always include at least 1 bomber piece of gear that is completely independent of the Sliding X. This helps prevent the allegedly dreaded accidental extension AND provides redundancy to the webbing used for the Sliding X. If you only use 1 Sliding X and that piece of webbing fails (highly unlikely) it would result in the complete failure of the anchor. Conversely I have seen 4 piece anchors using two sliding x's and I consider this to be an equally good alternative. Cordelettes/Web-olettes which are tied off have the advantage of having that same redundancy built in but lack the other advantages of the sliding x.

I just noticed that the information posted on Camp4 was resourced/republished from the ASCA website which surprised me.

http://www.safeclimbing.com/education/slidingx.htm

I find this interesting because I used to use the sliding X all the time on double bolted belays, before I heard the same things from some partners. Frequently I'd back up one leg with something static just in case one bolt blew - you were still doubled (at least webbing/carabiners). I think now I feel more comfortable with separate draws/runners for TR as everything is doubled - 2 bolts, 2 slings, 2 biners.

I mainly have been using the master cordalette for anchors. However, I do seem to have a hell of a time getting it to be equalized. One slight movement of the master knot and the entire anchor is on one piece. Of course generally the knot doesn't move around all that much so if a piece blew there isn't that much shock load. Apparently you are all saying that shock load (in terms of a 1 foot movement) isn't anything to be concerned about.

I'd be interested if anyone has ever heard of the X failing if set on two pieces and one of them has blown...shock loading the other piece that then blew. Especially if these were bolts?

Lately I've been doing more anchors where the X ties two pieces of gear together and this is backed up by a separate bomber piece. You don't need the cordalette then. Just a double and single runner (or quickdraw), which I find faster to rig, take down, and no cordalette hanging on the harness.

Make sure you put the twist in the sliding X system. I've seen this before...scary.



"We all fret over redundancy, but then it seems like everyone always just implicitly trusts that one biner on their harness or that one belay loop."

It is funny you say that because I feel the same about the new "auto" lock belay devices - ATC Guide or Reverso. One biner? The belay loop is supposedly the strongest part of the harness I have heard however. Then again they have broken before so where is the redundancy? Should we go back to rappiing/belaying through leg and waist loops?

That would really suck if your waist loop blew and you are hanging from leg loops, but better than nothing I guess.

I have a climbing partner who ALWAYS wears his Metolius Personal Anchor System when we are multi-pitching. Of course, his PAS is girth-hitched onto-his harness through BOTH his leg loops and his waist. He (short) clips his PAS into the locking biner that is connected to the rope/ATC when rappelling. This effectively backs up his belay loop while he is rappelling.

I've seen the trick and admit that it makes good sense but I rarely use my PAS these days so I don't tend to use this back-up. But, it does make sense and isn't hard to do if you regularly wear a PAS or similar piece of equipment.

Note: The 'biner to 'biner connection is composed of two locking biners which, while not ideal, is fairly safe. It's undoubtedly better than nothing if your belay loop fails.

I posted a somewhat lengthy reply to Mal's post on Super Topo. Rather than cross-post it here, the reference, if anyone is interested, is

http://www.supertopo.com/climbing/thread.html?topic_id=62436>>>>>

I use the rope and few slings...what is a sliding X??

"Also the sliding X is the AMGA certified way to set up top ropes from bolted anchors."

This is news to me. I have taken several courses and did not see a sliding-X tied once.

The important question to me is can the protection hold the worst possible force for the given scenario? If the answer is YES, then it seems that the method used to tie the protection into a system becomes less important so long as it maintains the redundancy of the system.

In the often cited S-R-E-N-E methodology, I think SOLID & REDUNDANT are the vitally important steps. Get these two right and the E-NE don't matter as much; get these two wrong and the E-NE don't matter as much.

I try to focus on placing good gear and learning everything I can about the fixed protection (and the rock that the fixed gear is in) at my local climbing areas.

By the way, Rock Climbing Anchors: A Comprehensive Guide, by Craig Luebben, is a must read. The section entitled How important is Equalization is especially relevant to this thread.

One thing to note with the sliding X; it's not an equalizing rig; it's a distributor; which you can/should manage with load limiting knots & angles.

Why look to an X for distributing a load over a rope or cordalette/no-extension rig? You have marginal anchors, as a whole, with the potential of side loading (a runout traversing pitch). If you have this, as Malcolm said, you are in a bad position & are playing the odds. I would also look to use cord as the sliding x rig because of the nylon cord material allows for more absorption than slings.

Irrespective of the rig, anchor quality (Solid) is the key; which means that limited extension x or a no-extension will work -- it will just be a matter of what creates redundancy & what is the best utility for the situation. (example -- why create some complex multi-point anchor when a simple tree/boulder-wrap will be more than adequate?)

Also, there is no "certified" way.