Build My Own FeedQC Lab: Retiring Old Ropes
We’ve all seen it at the cliffs, and I’m a major offender myself—climbing on old ratty ropes. Yeah, ropes are expensive and that’s the main reason people push their ropes to the limit—trying to squeeze every last ounce of use out of them until they become a dog leash or door mat. I’m not going to lie—I get sweet deals on cords, but still, I don’t like to be wasteful and usually end up climbing on my ropes a little too long.
Ropes can develop a sentimental value to some people—maybe it’s the cord you sent the “proj” with, or had a great trip up a Valley wall with—so you just don’t want to retire it. I had such a case—a special 9.4mm. I kept climbing and climbing and climbing on it. It was beat. It started out as a 70 m, then after endless days of constant whippers, it became a 65 m, then 60 m, then 55 m. I just didn’t want to see it go.
So one weekend I was taking REPEATED MONSTER whippers off the VERY LAST move of one of the many nemesis routes of mine. I had to skip the last clip because I’m too weak to clip it—and go for a huge chuck to the finishing bucket. I would sail onto the end of my trusty 9.4 mm time and time again. The last 10 ft or so of the cord were absolutely throttled—at the end of that weekend, it was time to say goodbye.
Of course, I brought it into the lab and figured I’d do some testing.
Testing
I decided just to test the ultimate tensile strength of the rope in different areas, and compare it to a brand new rope of the same model and make. We didn’t do anything fancy—just a figure 8 on each end, and pulled to failure in the tensile tester. We were just doing this quick and dirty for comparison's and curiosity's sake.
When tested like this, breakage at the knot is almost always the failure mode—and remember—figure eight knots can reduce the strength of a rope somewhere in the neighborhood of 25-30%.
Results
The first test we did was a piece from one of the totally worn-out ends. It broke at around 6 kN—and NOT at the knot.
Yowsa, I had just been whipping all over the place on that cord—and it broke at 6 kN, and NOT at the knot—scary stuff. Though the sporto falls I was taking were super soft (my wife was belaying and is light, and I am fat)—chances are the tension seen in the rope wasn’t anywhere near 6 kN, but if I had gotten slammed hard, low to the ground, etc??? It’s definitely possible to see these kinds of loads in the field.
We decided to do more tests on my cord—on the ends, and in the middle, as well as on a brand new 9.4 mm for comparison purposes. In all subsequent tests, the sample broke at the knot as expected, but we still saw some frighteningly low values.
| New 9.4 mm | KP’s 9.4 mm middle | KP’s 9.4 mm end |
| 15.6 kN | 9 kN | 6 kN* |
| 13.8 kN | 9.8 kN | 8 kN |
| 7.7 kN |
*broke in the middle of the test sample
We tracked down another beat 9.4 mm from one of the QA guys—and put it through the ringer as well:
| New 9.4 mm | Used 9.4 mm middle | Used 9.4 mm end |
| 12.9 kN | 11.9 kN | 8 kN |
| 13.6 kN | 11.9 kN | 9.8 kN |
| 11.6 kN | 8.6 kN |
Still curious and given the results we’d seen—the boys in the lab and I decided to do the same with some other tattered ropes that were around. We did similar tests with more Beal ropes as well as Sterling, Edelweiss, Mammut, etc. We found very similar results:
- The worn out, frayed, end pieces of any rope we tested were consistently significantly weaker than the middle sections of the same cord.
- We DID manage to find other samples that broke in the middle (as opposed to at the knot) – and at relatively low loads—less than 7kN.
- The end pieces, and middle pieces were consistently weaker than a section of a brand new cord.
Bottom Line
- Ropes, like all climbing gear, don’t last forever—the ends of your rope take a beating—be wary of super frayed, worn, puffed out, beat up tattered cords. Yes, ropes aren’t cheap, but they’re also your lifeline—literally—so take care of them.
- When the ends of your cord get all beat and tattered from dogging up routes, cut the ends off, or a buy a new rope.
- I always cut equal lengths off BOTH ends so the middle mark is always in the middle.
- Be sure to mark the new length on BOTH ends so you and your partners know what you’re dealing with.
- And while you’re at it—tie a knot in one end—too often you hear of someone being lowered off the end of their rope—definitely not cool.
- For me the most important thing… to train harder and get stronger, so I won’t be whipping in the first place.
Be careful out there,
KP
United States / English 
13 Dec 2011, 2:49AM
But this isn't really a test of just an aged rope; it's a test of a well-used aged rope.
15 Dec 2010, 9:04AM
Isn't this an excellent argument for us to transition to a Twin or Half rope system? I have designed mechanical systems for aircraft and from an engineering standpoint I would never be able to justify this in a system. Yet, I continue to dangle myself from a single rope on a regular basis. We are so careful building redundancy into our anchors but still have a single point of failure with our ropes. I would really be interested in the failure rate comparison between half/twin/single rope systems.
Would you fly in a plane when you are not sure about the structural integrity of the wing?
Usually at a minimum you have redundancy when you rely on a spring in a system.
thoughts?
2 May 2010, 10:25PM
Yes, you can look at the "Impact Force" in the rope's stats, but that is the Impact Force generated by a NEW rope. Probably the biggest change in a beat rope is that the dynamic softness goes away, and the Impact Force goes way up. Generating 1500 lbs of force is entirely possible. Scaaary!
For instance, on his sport route, if Kolin's wife had ground-anchored and used a gri-gri, that changes the dynamics a LOT! If the fall is at the third clip rather than the seventh, if the fall is a bit longer... etc. OK, generating 1500 lbs is not 'normal', but it is possible. Unfortunately the impact force test is very difficult to execute, but I think Kolin's main point is your sport climbing cord, with lots of falls, the ends get beat up, and ya gotta cut em off, because they become unsafe. Climbers trust gear that they should not.
Tom
29 Jan 2010, 10:25PM
how does a rope deteriorate with age alone without use
29 Jan 2010, 7:57AM
any pics of the ropes for comparison?
22 Jan 2010, 11:51AM
Good info an timely. We just got back from El Potrero Chico and got concerned near the end of the week when two of our ropes were getting fuzzy and felt a bit soft in places. I have heard 'if you can't see the core and you've not taken significant falls your rope should be okay'. So I am interested as others asked to get some more insight into HOW fuzzy and HOW puffy your rope was.
As always - thanks for doing the kind of testing and reporting that REALLY matters!
16 Jan 2010, 3:34AM
Aren´t there any more pictures? The data is interesting but I think most people would like to see the state of the ropes.
8 Jan 2010, 1:38AM
I would also appreciate posting som emore pictures of the rope. How didi it look like? How old has it been?
Cheers chris
7 Jan 2010, 10:58AM
1kn is roughly equal to the weight of the average American male wearing a moderate amount of gear. A very convenient number, no?
So to say a rope broke at 6kn, is to say the rope broke when 6 men hung from it -- 6 times the weight of one man.
To figure out how much peak force is exerted onto a particular piece of gear (pro) during a fall, you have to consider, weight of falling climber, distance of fall, stretch of rope, "fastness" of belayer (that is, does the belayer move as a result of catching the fall). A fairly difficult exercise.
Easier; you can look at the "impact force" number on your rope as a guide to what a "bad" fall might be like, in kn.
Easier still; you can look online for impact force calculators.
Easiest of all; keep your fall factors
6 Jan 2010, 11:55AM
So we saw your old rope breaking at as little as 6 KN. Will a typical fall generate this kind of force or will only a violent one (factor 1-2 fall or bing spiked by the belayer)?
6 Jan 2010, 10:30AM
Hi guys,
Thanks a ton for posting this, very informative. Any chance that you have any photos that you could post of the ropes before you broke them? It would be nice to actually see just how "frayed and puffy" the ropes were.
Cheers.
5 Jan 2010, 11:08AM
How beat was your rope? Age, days of use, any high factor falls, fuzzy, etc. Tks for all the testing you do KP...always interesting.
5 Jan 2010, 9:34AM
It's great to see the actual results of the ropes we all know are "sketchy" but still make runs on them. The way I see it is a rope is a lot cheaper than a trip to the ER. Thanks for keeping up the good work over at BD.