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shotwell
Apr 2, 2012, 5:23 PM
Post #26 of 30
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Registered: Jan 5, 2009
Posts: 341
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jt512 wrote: redlude97 wrote: jt512 wrote: I suspect that you're right that a good dynamic belay trumps the impact force of the rope. It would be interesting to see that hypothesis tested further, but I hope that you also do the test I suggested with a non-dynamic belay. Just don't get hurt doing it. Jay If impact force was a major factor in accidents wouldn't we see more reports of such cases? Getting slammed into the wall is probably the number one cause of injury in sport climbing. The question is, does a low-impact-force rope help mitigate the risk, or is the rope effect completely dominated by the belayer? Jay
So many variables to consider...
For example, I can only make my catches fairly soft for my wife. I am over 170, she is under 110. Having a rope that contributes to a harder catch doesn't seem like a great idea. I use a fairly low impact force rope for this reason.
At the same time, (considering dynamic elongation to be the same) I feel like this makes it easier for her to keep me off the ground in low fall situations. If the rope is absorbing more of the force from the fall, she shouldn't be picked up as far in my fall.
Extensive testing involving multiple ropes, catch types, and weight differentials is the only research that would cause me to change my current rope selection criteria. I really do feel a difference, even if it is simply psychological.
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USnavy
Apr 2, 2012, 5:56 PM
Post #27 of 30
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Registered: Nov 5, 2007
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jt512 wrote: USnavy wrote: The impact force rating of the rope is limited in how much it can reduce the pendulum effect. I tested this a few years back, where I took multiple lead falls on the same bolt, from the same stance on two different ropes. I compared a very high impact force rope (the Maxim Pinnacle) with soft catches from the belayer to a very low impact force rope (Beal Top Gun II) and hard catches. I found I slammed back into the wall significantly harder with the low impact force rope and hard catch. I repeated the test on multiple routes with multiple fall distances and in all cases, the low impact force rope with a hard catch from the belayer resulted in me slamming back into the wall far harder than a soft catch on the high impact force rope. I also compared the rope side by side with the same catch type (soft) and I did not notice a difference in regards to the pendulum effect. With respect to my concern about whether differences in the elasticity of different ropes are sufficient to significantly affect the impact force in actual falls, you didn't do the test that matters, which is to compare different ropes with the same "hard" (ie, minimally dynamic) catch.
I dont like high elongation rope for sport climbing because it greatly increases your chances of decking if you fall within the first 50', especially if you fall while clipping. There have been times where I had to stop someone from decking because they blew the third clip, and after I preformed a running belay their feet was dangling on the ground. If they would have been climbing on some rubbery Beal, I wouldent have been able to yank in enough slack. Thats happened twice on the same route.
Some ropes have static elongations that are double of what Maxim's ropes are. So in essence, they double your fall distance. Thats a big number! All for what? A slightly lower impact force? Thise rubbery Beals increase your fall distance quite a lot but provide minimal real world benefits for your average sport climber IMO. The only time I break out my Beal is if I am trad climbing or aid climbing, but even than I am not especially concerned. The first El Cap route I did was on a Maxim Glider which has an impact force rating of some 9.6 kN. So its a big whatever to me.
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sycamore
May 27, 2012, 10:41 AM
Post #28 of 30
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Registered: Dec 26, 2002
Posts: 161
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I've never noticed a marked difference in "catch hardness" between ropes. What people seem to forget is that after you've fallen or even hung on a rope, all those stats essentially go out the window. Your first fall of the day on a route may indeed conform to the rope's stats, but unless you allow full recovery of the core each time, it'll get harder and harder each time you fall
(a phenomenon I have indeed noticed), until you untie and switch ends, or give the rope sufficient recovery time.
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moose_droppings
May 27, 2012, 2:23 PM
Post #29 of 30
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Registered: Jun 7, 2005
Posts: 3298
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How do you know what the impact force of any rope is after it's been in use for a while, or after a couple hard falls on them? Some brands wear better than others in many aspects including elasticity. IMO Beal ropes get stiffer sooner with use than my NE ropes, sans scientific proof.
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tradmanclimbs
May 27, 2012, 5:13 PM
Post #30 of 30
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Registered: Apr 24, 2003
Posts: 2599
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If all yopu do is 1/2 pitch sport routs you are nuts to spend extra money on skinny ropes that wear out faster. the fatter rope has more material to help disperse the energy in a fall than a skinny rope. Lots of project fall and all the lowering into the mix and a fat rope makes perfect sense for sport cragging. One of my partners is a serious Sport climber and favors the Sterling Marathon. i have had that rope as well and it held up well. My last two ropes were 10.2 Beal. Very soft catches but the core wore out quickly on one of them. Sheath was fine all things considered but the core got all mushy?
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