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musicman
Jun 30, 2004, 6:31 PM
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so, as i was looking through my BD catalog, i noticed that the webbing, although incredibly strong for fabric, is 2 kn weaker than the 'biners. I was wondering if just placing one 'biner rated at 25 kn would be safer, now, i don't wanna hear about rope drag and all that, that is dependent on the long/draw just being longer, but if you took a fall onto one 'biner wouldn't it be stronger than a quickdraw? hope it all makes sence, thanks
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jerrygarcia
Jun 30, 2004, 6:37 PM
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I hope to god your not taking 25kn falls or 23kn falls.
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musicman
Jun 30, 2004, 6:38 PM
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agreed, but i was just thinking to myself if having a less stronger piece in between two other's made it fail easier,
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coldclimb
Jun 30, 2004, 6:42 PM
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Could be, but is it enough of a difference to matter? Ever heard of a draw breaking?
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tradklime
Jun 30, 2004, 6:43 PM
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Occassionally on sport routes you will see people clip directly into the hanger with a locking biner. This works fine, except for the rope drag issues you recognize.
For a long time climbers didn't use slings, they simply clipped 2 biners together on one bolt hanger. It was discovered the hard way that when two biners are clipped together there are some interesting dynamics when loaded in a fall, sometimes resulting in the rope coming unclipped. Adding a sling to the link seems to help mitigate this.
Forgot to add... The strength of the sling is plenty. If you generate 20+ kn in a fall, you'll have a lot of other problems.
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vegastradguy
Jun 30, 2004, 6:43 PM
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one carabiner rated at 25kn will be stronger than the draw, since the webbing is the 'weakest point' at 22kn.
that said, remember that most trad pro is rated between 10-14kn. this is considered fully rated for normal falls. anchors must be built to withstand far greater forces, but a regular fall isnt going to produce enough force to cause a trad piece to fail, let alone webbing or a carabiner.
theres also a multitude of reasons to use webbing that i havent got time to go into because i'm at work. rest assured, someone will shortly.
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rrrADAM
Jun 30, 2004, 6:47 PM
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Doesn't matter... The weakest link would be you rope, so that would break long before a biner or the webbing in a sling.
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musicman
Jun 30, 2004, 6:50 PM
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In reply to: Doesn't matter... The weakest link would be you rope, so that would break long before a biner or the webbing in a sling.
never thought of that, very true, and just for the record, i don't, nor was i ever planning on taking a 25 kn sport fall, and no i have never seen a draw break, once again, curiosity :oops:
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david.yount
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Jun 30, 2004, 9:12 PM
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Sport:
If you clip a biner thru a hanger and clip your rope to that biner, that anchor point is not as safe as using a sport quickdraw to connect your rope to that hanger.
It has nothing to do with some super strong biner rated at 25kN compared to some webbing only rated to 23kN. There are plenty of biners that are rated no more than some webbing. Regardless.....
1)
As you climb past that anchor point, your upward movement causes the rope to dance in that single biner. And as you fall the biner is again inspired to move from direct contact with the rope. That single biner can easily be bounced into a different position than when you first placed it.
One failure mode is the single biner being loaded across its minor axis. All biners have at least a 60% reduction in strength thusly.
2)
Each time you fall the biner attached to the hanger gets a nick cut into it, after a bit of "falling up a route" the biners attached to hangers get non-trivial sharp nicks cut into them. If you use a single biner to connect your rope to the hanger then when you fall your rope will be subject to those sharp nicks (assuming the biner has inverted due to dancing due to direct contact with the rope).
[note: quickdraws should have a designated hanger-end and designated rope-end]
3)
If you use single biners to clip the rope to each hanger, you will experience rope drag higher up, and on many routes the drag will be very significant. This can lead to injuries in several ways.
3.1)
You're going for a dyno, but the rope stops your motion like the backyard dog running to the full extent of it's chain. And you fall.
3.2)
You're pulling up on the rope to make the current clip and the rope stops your motion like the backyard dog running to the full extent of it's chain. And you fall.
3.3)
You're topping out on a mantle but the rope stops your motion like the backyard dog running to the full extent of it's chain. And you fall.
Any fall can cause serious injury or even fatality. Especially those that occur when on far easier terrain than the crux of a sport route. There was a fatality of a Seattle woman climbing at City of Rocks in Idaho when she fell near the anchors of a sport route. It was runnout from the last bolt to the anchors because that terrain was far far easier than the bulk of the route.
Being short roped while leading can easily cause falls.
4)
You lead on dynamic ropes because if you took a lead fall on a static rope you would experience injurious forces during deceleration. A dynamic rope that runs in a straight line when unloaded will provide it's full shock absorbing potential. A rope that runs zig zag will have severely diminished force limiting potential.
If you use single biners to connect your rope to hangers, most routes will cause zig zag in your line and when you fall your rope will experience a much greater force at the top anchor point as well as your body.
5)
I have several more points related to sport climbing but I'll trust this is sufficient to get you thinking and asking.
[Using a quickdraw helps isolate the movement and jiggling of the rope from the biner on the hanger. Using an open runner, a loop of webbing, further isolates the rope's movement from the biner on the hanger]
Trad:
Virtually everything already mentioned for Sport also applies here. With even more additionals; I'll mention four.
1)
If you clip your rope into a biner directly into your placement, while you climb past your placement it will almost always move; it will not remain in the same position as you placed it. This new orientation for your protection is likely inferior to your original placement. When you fall there is an increased chance of it failing.
2)
Unless you're at Indian Creek with splitter cracks your placements will not be in a line. As you progress up, the lower pieces will get tugged sideways toward the next higher piece. This movement compromises their placement.
3)
Each time you fall the rope is loaded and tries to form a perfectly straight line. Lower placements will receive significant sideways loading, generally moving them and compromising their placement. If your top piece blows and the lower piece(s) are compromised...... a catastophic example is the full zipper, depositing the lead climber on the ground.
4)
The holding strength of protection is unknown, always. The only tests that have been performed with significant statistical meaning are destructive tests; these tests measure the manufacturing strength of the piece. There are no tests involving holding strength.
Regardless.
I'm unware of any protection that is rated for greater destructive strength than the weakest rated runner. If the piece doesn't blow up then the runner will most certainly hold as well. Wether the runner is 7% weaker than the biner is moot.
Typcial destructive strengths vary from 18kN (rare), 13kN (common), 10kN (common) and on down to ratings that would only benefit aid climbers, 3kN, 2kN and even some pro is rated at just 1kN (225 pounds).
Most placements are far far weaker than the destructive strength of protection. If the placement holds, the runner will hold. The biner's strength relative to the runner's strength is again, moot.
But it's always good to ask questions, especially when you think you've just developed a better mousetrap!
David Yount.
PS Chris Harmston, formerly with Black Diamond in Salt Lake City reported on several occassions (technical safety engineer position) that he believes that forces greater than a modest 8kN are not occuring, based on his years reviewing equipment failure.
PPS Mammut 8mm Dyneema slings are da bomb!
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curt
Jun 30, 2004, 11:09 PM
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In reply to: Doesn't matter... The weakest link would be you rope, so that would break long before a biner or the webbing in a sling.
No, the rope will not break. The ultimate strength of a modern climbing rope is around 7,000 to 9,000 pounds (30 - 40kN). The reason that it does not matter if gear is rated for 23kN vs 25kN is that the rope stretches and has a maximum impact force rating of around 10kN.
Curt
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rrrADAM
Jun 30, 2004, 11:38 PM
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In reply to: Every rope has a "breaking strength," which means that if we place a heavy enough strain on a rope then it will eventually break. The Safe Working Load of a rope is generally considered to be one-fifth of the rope's breaking strength... and Modern ropes used by rock climbers often have a breaking strength of several thousand pounds when they are new...
The rope is also weakened approximately 20% by a fig 8 knot, and more so with smaller radius knots. Charts for weakening factor are also provided in the above link. Another thing to consider is the age and amont of abise and falls a particular rope has a history of.
In reply to: The maximum loads felt by a faller are suspected to be at most 15 kN ( 3372 lbs ). This is the load at which other parts of the system start breaking, such as the rope at the tie in knot, the top biner through the protection, and the faller's body being broken by the forces of de-acceleration. Thankfully, very few falls reach forces anywhere near this high, but we can view it as an upper limit.
This is due to the weakening of the rope by the knot. This "upper limit" is above that of a biner at 22kN, but approaching that of the rope at the knot.
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curt
Jul 1, 2004, 12:31 AM
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From www.neropes.com
In reply to: What is the Tensile Strength or Breaking Strength of a Maxim Rope? A dynamic rope is strong for its size. However, the rope is primarily designed to absorb the shock of a fall. A strong rope may or may not absorb fall better than one that is less strong. For this reason, UIAA does not require a tensile test for rope certification. To appease your curiosity, a dynamic rope will break at approximately 7,000lbs to 9,000lbs [30kN-40kN] depending on size and construction. Tensile strength should not be considered when choosing a dynamic climbing rope. It is not relevant to how a rope performs for rock climbing and mountaineering.
Even if the tie-in knot weakens the rope by 50% and you use the minimum breaking strength of 30kN, the rope will still not break. This same website shows the maximum impact force that any of the Maxim ropes will allow is around 10kN, due to the rope stretching.
Curt
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beesty511
Jul 1, 2004, 12:46 AM
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In reply to: The reason that it does not matter if gear is rated for 23kN vs 25kN is that the rope stretches and has a maximum impact force rating of around 10kN.
If the rope goes up through the gear and down to the fallen climber, the force on the gear could be 1.6 times the force on the climber, so even if the particular rope is able to limit the force on the climber to 10kN, 10kN is not the maximum force on the gear, and therefore 10kN is not the relevant figure to compare to 25kN or 23kN. In addition, assuming the rope is supposed to be able to limit the force on the climber to 10kN, that applies to an 80kg(=176 lbs) climber. If the climber weighs more than 176 lbs, he is going to feel more force on his end of the rope, and the gear is going to feel more force.
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dirtineye
Jul 1, 2004, 1:07 AM
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In reply to: In reply to: The reason that it does not matter if gear is rated for 23kN vs 25kN is that the rope stretches and has a maximum impact force rating of around 10kN. When you fall on gear, the force on the gear is roughly 1.6 times the force on the climber, so 10kN is not the maximum force on the gear, even if the particular rope is able to limit the force on the climber to 10kN, so 10kN is not the relevant figure to compare to 25kN or 23kN. In addition, if the rope is able to limit the force on the climber to 10kN, that is for an 80kg climber. If this guy weighs more, he is going to feel more force on his end of the rope, and the gear is going to feel more force.
Here we go again. Beesty, you really should check out that Beal impact force link I've been trying to get you to look at for several months. Really. THe force will be more, but it won't be a whole lot more, and you need a serious fall factor to get there in the first place. Um, by the way, how many ropes have broken over the top piece/biner in the last 5 years? How many biners have broken? HINT: more biners than ropes!
Sorry Curt, didn't mean to interrupt your fun.
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david.yount
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Jul 1, 2004, 1:17 AM
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Oh, yes, I also meant to address the rope idea.
Your rope will not break. Period.
Maybe it will fail in a pendulum fall involving an edge...
It most certainly will not fail in a clean fall onto a biner. Maximum destructive force a rope can withstand is far greater than webbing or biner.
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curt
Jul 1, 2004, 1:49 AM
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In reply to: In reply to: The reason that it does not matter if gear is rated for 23kN vs 25kN is that the rope stretches and has a maximum impact force rating of around 10kN. If the rope goes up through the gear and down to the fallen climber, the force on the gear could be 1.6 times the force on the climber, so even if the particular rope is able to limit the force on the climber to 10kN, 10kN is not the maximum force on the gear, and therefore 10kN is not the relevant figure to compare to 25kN or 23kN. In addition, assuming the rope is supposed to be able to limit the force on the climber to 10kN, that applies to an 80kg(=176 lbs) climber. If the climber weighs more than 176 lbs, he is going to feel more force on his end of the rope, and the gear is going to feel more force.
You are correct, but my original post in this thread was about the claim that the rope would break before any of the other gear--because it was the weakest link. So, that is what I was really addressing. Anyway 16kN (assuming the standard UIAA climber again) will also not break a piece of gear rated for 23kN or 25kN.
Curt
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kindredhawk
Jul 1, 2004, 2:05 AM
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In reply to: I hope to god your not taking 25kn falls or 23kn falls.
F=N=ma
1kg=2.2lbs. so if you weighed 220 lbs youd be 100 kg.
our climber in a static position would weigh 1000N or 1 kN
25kN=25,000N=25,000kgm/s^2 so if you weighed 100 kg the deccelleration would be 250m/s^2 and assuming it was done in 1s the velocity change would be 250m/s to 0m/s in 1 s
to break a 25kN biner youd have to decellerate at 250m/s^2 if that decceleration was achieved in 1 s you would have to be going 250m/s and to fall at 250m/s youd have to fall from 3125m
cause eq1:v (final)=v(initial)+at^2 & eq2:x=v(initial)=.5at^2
so vf=250, vi=0, g=a=10m/s we can derive the time of fall at 25s using eq1 then figure distance using eq2 at 3125m. now i think this is right using a lot of assumptions but who knows its bound to be better than what i put up before. i still think there is not much to worry bout. i worry about wear and tear on draws cause then who knows how much weight and force it will hold
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drrock
Jul 1, 2004, 3:17 AM
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curt
Jul 1, 2004, 3:23 AM
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In reply to: In reply to: I hope to god your not taking 25kn falls or 23kn falls. to create a force of 9kn assuming you weighed 220lbs. (100kg) you would need to fall about 400 meters. thats almost half the way up the nose on el cap. i think you can rest easy with a quickdraw bro. F=N=m * a 2.2kg=1lbs. so if you weighed 220 lbs youd be 100 kg and the accelleration of gravity is 9.8m/s2 i just use 10. our climber in a static position would weigh 1000N or 1 kN and the UIAA is just being safe it is there job.
I think some of your physics calculations may need to be revised.
Curt
(Edited so as to not sound like a total asshole.)
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kindredhawk
Jul 1, 2004, 3:46 AM
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curt is right my physics suck.... well i guess that's why i climb rocks and am not a physicist.... woe as me. so since i have a broken hand and can't write out the correct solution just call me and idiot and please no need to use curse words :-) curt why dont you figure out the right figures. thanks bro and keep it real... dolla dolla bills ya'll
is that better jay :-P probably not :-(
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curt
Jul 1, 2004, 3:47 AM
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In reply to: curt is right my physics suck.... well i guess that's why i climb rock and am not a physicist.... wow as me so since i have a broken hand and can't write out the correct solution just call me and idiot and please no need use curse words :-) curt why dont you figure out the right figures thanks bro and keep it real... dolla dolla bills ya'll
I sent you a PM, explaining what I meant.
Curt
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jt512
Jul 1, 2004, 4:09 AM
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In reply to: curt is right my physics suck.... well i guess that's why i climb rock and am not a physicist.... wow as me so since i have a broken hand and can't write out the correct solution just call me and idiot and please no need use curse words :-) curt why dont you figure out the right figures thanks bro and keep it real... dolla dolla bills ya'll
Your English isn't so hot either.
-Jay
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