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JimT
climber
Munich
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Sep 13, 2014 - 05:12am PT
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There are other reasons why some of the extension/impact force testing isn´t as revealing as it should be. Generally the set-ups are as shown in all the photo´s in this thread with the central karabiner nicely in the middle of the two limiting knots. Logically however if you require that amount of movement in the anchor to cope with load shift then you need to test when the load has moved, i.e at one end or the other where the extension is potentially worst.
Top-roping what you do is irrelevant but this doesn´t make dynamically equalising anchors desirable for multi-pitch.
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Tvash
climber
Seattle
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Sep 13, 2014 - 08:38am PT
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a rabbolet's just a long rabbit (metolius...)
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BG
Trad climber
JTree & Idyllwild
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Sep 13, 2014 - 09:48am PT
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Tvash
climber
Seattle
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Sep 13, 2014 - 09:52am PT
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Not full strength. Not dynamically equalized.
One side takes nearly all the load in a fall.
Just sayin.
I'm gonna try the quad (with a full strength runner, not a clothesline o let). That seems to provide the best of all worlds.
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:03am PT
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Not if you're awesome.
Are you...awesome?
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:07am PT
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I mean truly...AWESOME
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:08am PT
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If not, then...
...BEHOLD, THE LOCKER THAT BLEEDS!
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Tork
climber
Yosemite
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Sep 13, 2014 - 10:15am PT
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Not full strength????
I can not think of a single top rope situation that this isn't 100%.
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:34am PT
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"Not full strength????
I can not think of a single top rope situation that this isn't 100%."
The strength of an anchor is independent of how it's used if it's built to be omni-directional and dynamically equalized.
7mm accessory cord (typical cordelet) has a rated strength of 11 kN - as compared to 22 - 25 kN for a dyneema runner - which is also lighter weight. This can make a difference when the anchor is shock loaded (one pro point fails - not unheard of with a trad anchor when catching a lead fall). It's pretty much free extra safety, anyway.
That's all I'm sayin'.
Not a huge deal for top roping, obviously. For hanging belays on walls with haul bags? I go for all the strength I can get.
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the Fet
climber
Tu-Tok-A-Nu-La
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Sep 13, 2014 - 10:43am PT
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An advantage of the quad/X over the cordolette in the photo above is no messy knot to undo after a bunch of falls.
The only thing I don't like for two bolts on TR is a quick draw clipped to each one separately. You don't have two reversed opposed biners on the rope connection which is a red flag to me. I could see someone climbing above the anchor or the biners clashing together and unclipping a biner, then you are only on one biner which isn't enough safety factor.
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OR
Trad climber
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Sep 13, 2014 - 10:47am PT
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Just checking in on this soon to be 100 page dork a thon thread of tech weenies going berserk. NTTIAWWT ;)
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Tvash
climber
Seattle
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Sep 13, 2014 - 10:48am PT
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For TRing just use all lockers. Problem solved.
It's a dork a thon - but if you've ever known anyone who was almost kilt by an anchor failure (I have), sometimes being a dork is just OK.
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Josh Nash
Social climber
riverbank ca
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Sep 13, 2014 - 10:55am PT
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Why am I seeing three ovals on a lot of pics? I thought two opposed lockers or two opposed out facing gates at the least is ok.
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j-tree
Big Wall climber
Typewriters and Ledges
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Sep 13, 2014 - 11:38am PT
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"Hmmmm a thread about TR anchors?, This would be a great place to post my opinions and relevant experience about multi-pitch anchors for belaying a lead climber."
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Josh Nash
Social climber
riverbank ca
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Sep 13, 2014 - 11:53am PT
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3 is standard for TR'ing...
for only a couple of years...so yeah not long at all.
Why three? is it for redundancy or rope handling?
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JimT
climber
Munich
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Sep 13, 2014 - 12:04pm PT
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They sit on the rock better to stop any twisting in the NooB-a-Lette forcing the rope to rub.
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adam d
climber
CA
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Sep 13, 2014 - 12:08pm PT
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3 ovals makes a great TR masterpoint. Wide radius for the rope to run over for less friction and wear, opposite and opposed for security, symmetrical and the carabiners play nice with each other and don't pinch or load funny like some other combinations.
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rockgymnast
Trad climber
Virginia
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Sep 13, 2014 - 01:03pm PT
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I was led to believe that adding additional biners increased the friction, not decreased it.
That is why when rappelling, if one needs more control/friction, you would use 2 biners on your belay loop/rappel device.
Am I mistaken?
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Tvash
climber
Seattle
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Sep 13, 2014 - 01:37pm PT
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When you add more biners rapping - it tightens the radius of the bend in the rope as it passes through your device, increasing friction.
Adding more biners to a TR anchor increases the radius of the power point - and therefore increases the area upon which the force of the rope is applied. More area = less force/area = less pressure = less friction.
Wide ski versus skinny ski, etc.
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rgold
Trad climber
Poughkeepsie, NY
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Sep 13, 2014 - 01:48pm PT
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That would be a nice explanation if friction depended on pressure, which it does not, at least not the classical version.
Since you get the same 180 degree bend in the rope (split into two 90 degree bends) and then friction along the top surface, my guess is the three carabiners provide more friction than one in a top-rope setup.
There may be other reasons to use them, but decreasing friction isn't one.
Adding a biner to the rappel can either increase or decrease friction, depending on whether or not the added biner is clipped to the belay loop. So there isn't any fundamental principle that equates more biners with more friction independent of the configuration involved.
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