XEROS Climbing Rope Testing

... Aug 17th 2022
XEROS Climbing Rope Testing with Rob Pizem

Sterling Athlete Rob Pizem climbed over 100,000 vertical feet on an early prototype sample of XEROS and never even trimmed the ends. He did this as an extreme test of durability. We do not recommend pushing the life of your rope so long. He thoroughly documented the rope’s journey through two blog posts. If you’re interested in the life this rope has had, you can read them here:

Climbing Rope Initial Review- Rob Pizem first 21k of climbing
XEROS Climbing Rope Review Part 2 up to 70k feet of climbing

This rope was from our first round of field test samples we sent out when testing our XEROS technology over 18 months ago. We asked for it back to see how the water treatment was holding up. While we had the rope, we decided to do some non-XEROS related drop testing since Piz did such a great job documenting how he used the rope throughout its lifespan.

What we learned:

  • XEROS lasted the lifetime of the rope
  • This rope should have been retired long ago
  • Know how to tell if a rope needs to be retired and what that means
  • Close-up of Tested Rope

Initial scan of the rope:

When we received the rope back, we could tell the rope was beyond retirement. The last 10 feet on either end of the rope showed extreme wear. That last section of rope is where it runs over the carabiner during a lead fall and that’s typically where soft spots develop.
As we ran our hands over the rope, the worn spots didn’t seem to have any structural integrity left- it felt like a giant fuzzy shoelace. The rope totally failed the “pinch test”- a common way to determine if a rope should be retired or trimmed, even if the sheath is still intact. It’s commonly stated that the pinch test is a practical way to check for core damage.

  • Pinch Test on a New Rope vs. Old Rope

Rope End Drop Tests (A1 & B1):

We conducted the normal drop test that is used by UIAA to determine how many “falls” a rope is rated for. This is an extremely severe test that will subject the rope to more force than it should ever see in the real world. It involves an 80kg steel mass taking a factor 1.7 fall onto the rope repeatedly. We think it makes a good point of comparison for how much “life” is still left in a rope. Few things to note about our test:

  • We followed all the standard UIAA drop test procedures and rules, but we’re not going to list them here because they’re boring.
  • The forces being measured represent the force seen at the anchor or top piece of protection during a lead fall.
  • In real life it is very hard to generate a force above 6 kN during a climbing fall. This test generates around 9 kN on the first drop and the force will increase on each consecutive drop because the rope is losing its ability to absorb energy.

We tied our mass to the end of Rob’s rope, the same way he’d been tying into it to climb, and we did the first drop. The sheath exploded. Usually, they fail where they run over the edge, but this one blew up in the middle of the rope where the softest spots were.

The mass didn’t hit the ground though, some of the core strands remained intact and they successfully held the fall.

  • Picture of rope after drop A1.

The sharp drop offs in the middle of this force chart represent when the sheath and core strands snapped. 

Second Test (Zero Fall Rope B1):

We repeated this test on the other end of the rope. It snapped and the mass hit the ground.

Obviously, the rope was still strong enough to catch a normal climbing fall from Rob (because Rob’s still here with us today), but it went from being able to handle 5+ UIAA rate falls when new to not withstanding a single UIAA rated fall after extreme overuse.

Third Test (Trimmed Rope B2):

We trimmed the last 5m off the rope (as if Rob had trimmed the soft spot and made his 70m into a 60m). Then we tied that new end into our 80kg mass. It’s interesting to note here that the rope looks very used, but it passes the pinch test and visual inspection, like a climber would do.

The rope held the first fall with no problem, but then snapped on the second fall.
This was a critical result as it passed our visual inspection, but only held for one UIAA rated fall. However, there is some consolation knowing that this rope still caught one absolute worst-case scenario fall after being dragged through 100,000 ft of climbing, rappelling, top rope soloing, and route development.

Water Absorption:

We wanted to answer the question- does XEROS Dry Technology last the lifetime of the rope? In order to find out, we ran the UIAA Water absorption test on Piz’s rope.

  • The UIAA Dry certification involves abrading a rope, exposing it to a running stream of water for 15 minutes, and measuring how much water was absorbed by comparing its weight before and after.
  • We observed all the normal procedures except the abrasion because Rob had already abraded this rope plenty.
  • For the water absorption test we took a section from the middle of Rob’s rope. About 80% of Rob’s rope showed a very uniform amount of wear and the middle was representative of this.
  • A passing score for UIAA dry is <5% water absorption. This extremely used XEROS rope absorbed 6.5%, which was shockingly good for a rope in this state! It isn’t technically UIAA dry any more, but it’s still 3-4X better than an untreated nylon rope! With that data in hand, we’re very confident in saying that XEROS lasts “the lifetime of the rope”. Even though it’s an oil-based coating and not a fluorine-based chemical, like our old dry treatment, it still as effective in protecting your climbing rope from water.


XEROS Dry Technology will last the lifetime of your rope keeping it lighter and stronger in wet and humid conditions.

Climbing rope is very tough, but it doesn’t last forever. You must be vigilant at inspecting your rope. Look for obvious signs of damage like holes in the sheath, weird bulges, or dents in your rope. Also check for soft spots and perform the pinch test on suspect areas, it’s the best way to quickly judge the integrity of your rope. But as seen on the third test, a visual inspection isn’t always 100% reliable, and if you have any doubt in the integrity of your rope, it should be retired.