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Quad made from 2 dyneema slings?

David Gibbs · · Ottawa, ON · Joined Aug 2010 · Points: 2
JCM wrote: He had two designated anchor draws, with locking DMM revolver biners on the rope side. The revolvers made pulling the rope through on toprope oh-so-smooth.
NO! Don't do that! The friction across the top anchor is very important for a safe top-rope setup where the climber weighs more than the belayer.
eli poss · · Durango, CO · Joined May 2014 · Points: 525
Greg Sievers wrote:I did not read thru the entire thread here: but I would NOT suggest asking the "general public" technical questions. that's a good way to get hurt. ask a professional, go to the sling manufacturers website, read up in Freedom of the Hills, or ask an industry professional. some dyneema materials are NOT recommended for knotting, they cinch, burn, and fail at less than spec'ed values, under dramatic loading.
As long as you aren't stupid, mountain project is good enough to "approve" something that's bomber. I really hope you're just trolling, though.

David Gibbs wrote:More decisions as to where to put those knots. When clipping the rope biners to a quad, you need to clip each biner to different strands in the quad, while in the master-point, you just clip both biners to both strands in the master-point. Another disadvantage of the quad, is that it is essentially a single-application tool. TRing on a two-bolt anchor. It doesn't extend well to multi-pitch sport, and it definitely doesn't extend well to trad anchors where you will often have more than two points. A master-point anchor extends to both of these as well. Why learn something that is so situation-specific, yet with no effective advantages, and some disadvantages?
1 You can clip two biners into the same three strands or clip 2 biners into two strands each.

2 Have you ever climbed multi-pitch sport? Because the quad is perfect for multi pitch sport where the anchor is always two bolts and you may have smaller stances at the belays. With a small stance, its nicer not to load a masterpoint in two opposite directions.
Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 252
David Gibbs wrote:- Another disadvantage of the quad, is that it is essentially a single-application tool. TRing on a two-bolt anchor. It doesn't extend well to multi-pitch sport, and it definitely doesn't extend well to trad anchors where you will often have more than two points. A master-point anchor extends to both of these as well. Why learn something that is so situation-specific, yet with no effective advantages, and some disadvantages?
Actually, that's probably the least useful application of a quad (as discussed, it's overly complex and overkill for TR). I know plenty of people who use quads for sport multipitch, particularly if you're going with a big group (regular master points can become a cluster pretty quickly). With a quad, you can have 2 things clipped to 2 different loops and still have room on the shelf. It's also nice to have something self equalizing if the belayer needs to change stances or the next pitch traverses. You can also used it for trad by splitting the upper arms (up to 4 pieces this way, or you could get creative and link pieces via sliding x's). Of course, this starts getting super complicated and a regular masterpoint might be better due to speed and simplicity, but the quad really is designed to be a multipitch anchor, not an overkill TR.
mediocre · · Unknown Hometown · Joined Jul 2013 · Points: 0

Why are we even talking about the quad? Use a sliding-x and call it good.

End of thread.

Anonymous · · Unknown Hometown · Joined unknown · Points: 0
divnamite wrote: Do you ever use one piece for anchor? I get that JCM doesn't like equalization, which is fine in my opinion because perfect equalization doesn't happen real life. The idea is about back up as you said. So what method do you use to do two bolts anchor? Well, if the two bolts aren't anywhere even, then using a simple master point system does a really good job of that.
The only time I use a single piece is if it is like a 2ft thick tree on solid ground and even than I still normally wrap 2 slings around it.

I have a short piece of climbing rope 7-8mm (i think forget what the exact size is) that I have tied together with double fisherman. I run it through biners on both bolts and tie a knot at the master point. It is fast and easy and works, if climbing a multipitch with perfectly spaced bolts I don't even unite the master point.
David Gibbs · · Ottawa, ON · Joined Aug 2010 · Points: 2
eli poss wrote: 2 Have you ever climbed multi-pitch sport? Because the quad is perfect for multi pitch sport where the anchor is always two bolts and you may have smaller stances at the belays. With a small stance, its nicer not to load a masterpoint in two opposite directions.
Yes. In Canada, US, Mexico, and Switzerland.

I generally just use master-point anchors for that, too. Don't usually bother untying them.

I guess in the particular case of a small stance that you're going to be sharing for a bit of time (though, mostly, you don't need to share stance for very long on sport, it isn't as if re-racking takes much time), then being able to lean different ways and not pull each other around could be nice.
Pete Spri · · Unknown Hometown · Joined Jun 2009 · Points: 347
eli poss wrote: 2 Have you ever climbed multi-pitch sport? Because the quad is perfect for multi pitch sport where the anchor is always two bolts and you may have smaller stances at the belays. With a small stance, its nicer not to load a masterpoint in two opposite directions.
Why would you use a quad vs using 2 runners, both with sliding X to self-equalize? You are redundant with that set up and no knot tying.

I dont see the advantage of 1 x 240cm sling tied with 2 knots vs 2 x 120cm slings self equalized. Two sliding x is redundant, faster, and better equalized, and the 120cm slings are more versatile. What am I missing with the Quad set up?
Brian L. · · Unknown Hometown · Joined Feb 2016 · Points: 90
Pete Spri wrote: What am I missing with the Quad set up?
I'm not going to argue the merits or detractors of what you suggested, just this:

What you're missing is that there's more than one way to skin a cat. Pick your poison, and go climb.
David Gibbs · · Ottawa, ON · Joined Aug 2010 · Points: 2
Pete Spri wrote: Why would you use a quad vs using 2 runners, both with sliding X to self-equalize? You are redundant with that set up and no knot tying. I dont see the advantage of 1 x 240cm sling tied with 2 knots vs 2 x 120cm slings self equalized. Two sliding x is redundant, faster, and better equalized, and the 120cm slings are more versatile. What am I missing with the Quad set up?
A straight up sliding-X (without limiter knots, as you seem to be suggesting) is a bad idea in this scenario. If one of the bolts fails, you have extension, possibly quite nasty extension as you fall to that end of the sliding X, generally without a climbing rope to provide shock absorption in the fall. If both your slings, and your tether are dyneema, this can be intense enough to be painful or cause injury.

Also, you suggest the sliding X for equalization -- equalization is a pointless exercise on a pair of bolts. You want, in priority order, redundancy then lack of extension.
Pete Spri · · Unknown Hometown · Joined Jun 2009 · Points: 347
David Gibbs wrote: A straight up sliding-X (without limiter knots, as you seem to be suggesting) is a bad idea in this scenario. If one of the bolts fails, you have extension, possibly quite nasty extension as you fall to that end of the sliding X, generally without a climbing rope to provide shock absorption in the fall. If both your slings, and your tether are dyneema, this can be intense enough to be painful or cause injury. Also, you suggest the sliding X for equalization -- equalization is a pointless exercise on a pair of bolts. You want, in priority order, redundancy then lack of extension.
If you really have a bolt that could fail, using a sliding x is far superior to keep it from failing in the first place than a non-equalizing set up.

And even if a bolt fails, you still wouldn't have enough force even with a shock load to break the sling OR the remaining bolt.
that guy named seb · · Britland · Joined Oct 2015 · Points: 236
mediocre wrote:Why are we even talking about the quad? Use a sliding-x and call it good. End of thread.
Your suggestion is befitting to your name, sliding X has been shown to be ineffective and dangerous, look at dmm's testing.
dmmclimbing.com/knowledge/s…
clearly no one's seen this.
mountainproject.com/v/knot-… Also old thread.
Pete Spri · · Unknown Hometown · Joined Jun 2009 · Points: 347
that guy named seb wrote: Your suggestion is befitting to your name, sliding X has been shown to be ineffective and dangerous, look at dmm's testing. dmmclimbing.com/knowledge/s… clearly no one's seen this. mountainproject.com/v/knot-… Also old thread.
Your statement is as false as your misunderstanding of the DMM test that you linked.

The dmm test is looking at people tied into the anchor taking a static fall and the forces that would be generated ON THE CLIMBER, not on the bolts/pro. The reason that the force is highest in the sliding x is because the bolts are so well equalized in the sliding x that full force was transferred to the tie in point. The point of the DMM study is to show what set ups you will hurt yourself on the most if you climb above your anchor on a static tether and fall, NOT about spreading out forces on the pro.

The BD study linked earlier in the thread shows just how strong the sliding x is... stronger by far than any permutation of a limiter knot: rockandice.com/lates-news/clim...
eli poss · · Durango, CO · Joined May 2014 · Points: 525
Pete Spri wrote:The reason that the force is highest in the sliding x is because the bolts are so well equalized in the sliding x that full force was transferred to the tie in point.
This is hilarious. Thank you
Pete Spri · · Unknown Hometown · Joined Jun 2009 · Points: 347
eli poss wrote: This is hilarious. Thank you
Not sure if you don't get it or what.

Edit to add:

The dmm study shows nylon spreads force out better than dyneema, and that knots will lower force on the tie in point, but lead to failure of slings.

Moral of the dmm study, tie in with the climbing rope to a master point, not a sling whether nylon or dyneema (and expect knotted dyneema to fail), regardless of configuration.

Moral of the BD test, sliding x is the strongest configuration for maximum force that you can establish at an anchor.
Shane1234 · · Australia · Joined Jun 2016 · Points: 10

Here's another reason not to use sliding X, rockfall.

Rock fall cuts anchor

Pete Spri · · Unknown Hometown · Joined Jun 2009 · Points: 347
Shane1234 wrote:Here's another reason not to use sliding X, rockfall. Rock fall cuts anchor
I think that is about the only reason, assuming you are doubling up to 10mm dyneemas for redundancy. Rockfall will even ruin a redundant sliding x if it takes out one side.
Anonymous · · Unknown Hometown · Joined unknown · Points: 0

I would never use sliding X unless it was maybe at the top of a single pitch route where there was no risk of rock fall... even than there is no reason to risk redundancy for a little extra strength. If you want do a sliding X + another master point knot as a backup that would give you 3 pieces that would have to be cut and give you the highest strength.

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 252
Pete Spri wrote: Why would you use a quad vs using 2 runners, both with sliding X to self-equalize? You are redundant with that set up and no knot tying. I dont see the advantage of 1 x 240cm sling tied with 2 knots vs 2 x 120cm slings self equalized. Two sliding x is redundant, faster, and better equalized, and the 120cm slings are more versatile. What am I missing with the Quad set up?
You're redundant in terms of soft goods, but not in terms of protection; if one of those pieces blew, both of your slings would suffer massive extension. A quad is fairy similar to a sliding X with limiter knots, and equalizes just as well as a sliding X. It's also just as fast because it can be pretied. Have you tried clipping three people into a sliding X?
mediocre · · Unknown Hometown · Joined Jul 2013 · Points: 0

Like fish in a barrel

Pete Spri · · Unknown Hometown · Joined Jun 2009 · Points: 347
ViperScale wrote:I would never use sliding X unless it was maybe at the top of a single pitch route where there was no risk of rock fall... even than there is no reason to risk redundancy for a little extra strength. If you want do a sliding X + another master point knot as a backup that would give you 3 pieces that would have to be cut and give you the highest strength.
On Sport routes I typically use standard draws. On trad, I frequently incorporate a sliding x between 2 of my anchor pieces.

A lot of people mindlessly dismiss the sliding x, but when a straight sliding x cant be broken on a machine at the limit of 35kn... That test really shows how well a sliding x distributes force. On the order of 30% better, if not more.
Guideline #1: Don't be a jerk.

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