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Rope Stretch

Original Post
Superclimber · · Unknown Hometown · Joined Mar 2009 · Points: 1,310

Maybe this is a dumb question. Has anybody noticed an appreciable difference between a dynamic elongation of 33% versus 34%?

I have a Beal Joker 9.1 that the literature says has a dynamic elongation of 34% that I've been using for about a year. My older Edelweiss Rocklight 9.8 has a dynamic elongation of 33%. However, the Joker seems to stretch a lot more in real life falls. Or maybe it's my imagination. Thoughts?

J Walpole · · Unknown Hometown · Joined Nov 2012 · Points: 105

A new rope will have much more stretch than an old rope. As you use the Joker more you should notice less stretch.

David Gibbs · · Ottawa, ON · Joined Aug 2010 · Points: 2

Yup, ropes lose their stretchiness over time -- both static and dynamic elongation drops off. One reason that you would prefer a newer rope if leading iffy trad, ice, or anything else. But, when top-roping something, you might actually prefer an older rope with less stretch.

bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065

Whats the static elongation of either rope

Remember that the uiaa test a factor 1.77 fall for the dynamic number ... Something you hopefully never experience

A small fall higher up in the pitch will stretch much less

;)

Superclimber · · Unknown Hometown · Joined Mar 2009 · Points: 1,310

The static elongation is 7.5% for the Edelweiss and 8% for the Joker.

I've been on the Joker for a year and it's starting to get a little beat up, so it's pretty broken in. I'm sure age and use are factors, but it sure seems like a big difference between the two ropes in actual use.

What I'm really wondering is if others using the Joker (or another rope rated for use as a double and single) has noticed a big difference in rope stretch.

Greg D · · Here · Joined Apr 2006 · Points: 883

Keep in mind, the newer rope will have a slicker surface. Also, skinnier ropes have less drag over the rock and through gear. So, the newer, skinnier rope is incorporating more rope in the fall. Hence, more stretch.

bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065

If you TR and project with the 9.8 ... Itll stretch it out decently

Probably more than the 9.1 as you use the 9.8 more

Beal ropes are known to be stretchy ...

Also note that the joker has a lower impact force than the edelweiss

Also a thinner rope slides through most belay devices a bit more

;)

20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
J Walpole wrote:A new rope will have much more stretch than an old rope. As you use the Joker more you should notice less stretch.
Actually the opposite is more correct, although it's kind of complicated. Old ropes tend to have higher static elongations, but lower dynamic elongations when compared to new. So when TRing, an old rope will feel more stretchy, but when taking whippers on the first bolt or two, it will feel less stretchy. Of course that is a generalization and it changes depending on the rope, but that is more or less true of most ropes.
20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
Superclimber wrote:Maybe this is a dumb question. Has anybody noticed an appreciable difference between a dynamic elongation of 33% versus 34%? I have a Beal Joker 9.1 that the literature says has a dynamic elongation of 34% that I've been using for about a year. My older Edelweiss Rocklight 9.8 has a dynamic elongation of 33%. However, the Joker seems to stretch a lot more in real life falls. Or maybe it's my imagination. Thoughts?
Another thing to consider is that the Beal Joker has a much lower profile than a 9.8mm rope, and so it will allow the rope to stretch more. You could take two ropes of the exact same specifications, less diameter, and the rope with the lower diameter will likely stretch more just because it's smaller profile produces less drag through the biners and belay device and so a greater percentage of the rope is allowed to elongate.

As far as 33 vs 34 goes, we are talking about maybe a 0.66% difference on most single pitch falls, so no the elongation spec alone is not causing what you are experiencing. It is most likely a combination of the different ages of the two ropes and the diameter differences. The Beal Joker is a stretchy noodle and most ropes stretch less.
Superclimber · · Unknown Hometown · Joined Mar 2009 · Points: 1,310

Thanks for the replies and the insight.

I suspect the longer falls are the result of a mish/mash of factors. Regardless, I think the take away is to expect more stretch from the skinny rope and to take that into consideration when judging the striking distance to hazards. Nevertheless, I've found it to be a great rope especially for trips to the mountains. But maybe not the best choice for some objectives.

Ray Pinpillage · · West Egg · Joined Jul 2010 · Points: 180
20 kN wrote: Actually the opposite is more correct, although it's kind of complicated. Old ropes tend to have higher static elongations, but lower dynamic elongations when compared to new. So when TRing, an old rope will feel more stretchy, but when taking whippers on the first bolt or two, it will feel less stretchy. Of course that is a generalization and it changes depending on the rope, but that is more or less true of most ropes.
Source?
Guideline #1: Don't be a jerk.

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