Not true about the core threads melting. The article actually suggests that the mantle (sheath) abrasion and melting are the theoretical failure mechanism, which seems wrong to me. However, I haven't studied this much. Do you have any real reason to believe the core threads melt? Or is this just a guess. Seems a lot more reasonable to assume that a few core threads break in extreme falls, creating weak spots that propagate across the core during successive falls.

The test also implies that ropes with higher fall ratings should be more durable.

To increase the number of falls held, while holding materials and construction constant, one would add more core strands.

I'd actually be interested in running some rope failure analysis tests, trying to observe the failure in the rope after each "fall." I'd hypothesize that some core threads break after each serious fall, and that failure propagates through during successive falls. Do you think the UIAA would sponsor some research?

Will and Shoo, See my other posts about "recovery" time and polymer elasticity. I contest that there is actually no "recovery" effect or loss of elasticity during sequential drops. If you can prove otherwise, I'd be very interested.

Will and Shoo, See my other posts about "recovery" time and polymer elasticity. I contest that there is actually no "recovery" effect or loss of elasticity during sequential drops. If you can prove otherwise, I'd be very interested.

This doesn't show any data to prove it, but it does present a statistical model suggesting that ropes do, in fact, lose and recover elasticity based on the timing of a series of impacts. onlinelibrary.wiley.com/doi/10.1002/jst.62/pdf Edit: I take that back. There is data in there suggesting that this is true.

The # of falls is a relevant statistic to have on a label. It's just that most climbers won't care or will misinterpret what the stats really mean. # of falls held is a good second indicator behind impact force on the ropes ability to provide a soft catch. Highly relevant to climbers with marginal gear and/or heavy bodies. If someone buys a rope with more falls held thinking it will "last longer" or be more "Safe" they do so mistakenly but with no "risk" to themselves or others. The rope will still hold falls just fine. An explantation of HOw the numbers are relevant to rope performance and why that matters would be a welcome ADDITION to rope tags. They should also quote % sheath thickness on each tag. They should REMOVE the thickness measurement as it has far too much +/-. 0.3mm is the allowable variation. More emphasis on weight per meter. Much better indicator. The 55kg double rope weight is completely legit. You just need to know the why's and how's of the process. Doubles need to hold 1 UIAA 80kg drop test. 1 fall is a bit challenging stats wise so they came up with another method to test. The DAV figured out that 5 falls with 55kg is the same as one with 80kg. See below for the benefits of this. From ST - "to the effect that the UIAA standards require a 'single' rope to hold at least 5 test drops before breaking; and they require a HALF rope to hold at least ONE (80kg) drop in the same test, because it typically holds an entire fall on its own in double-rope climbing, when the second-last piece is some distance below the last one. Now here's the point: one is an awkward number because if the rope survives one drop but breaks on the second one, it could be that it BARELY held ONE, or it could be that it NEARLY held TWO, or anything in between. It would be nice to know a little more, since conditions, age, or manufacturing irregularities could push the result over the line at either end, particularly below the one-drop end. So the UIAA looked for a drop-weight that would abuse the rope the same amount in 5 drops as the 80kg would abuse it in ONE. That turned out to be about 55kg. Now the testers can drop away, and have more data to compare between different ropes or different chunks of the same rope: if a particular rope never breaks on the 4th drop, and sometimes makes it to 7 or 8, they can say it's definitely a solid half-rope. But if it sometimes breaks on the 3rd or 4th drop, they may eye it suspiciously, and re-rate it as a twin or send it back to the lab for beefing up."

Curious as to where some of this information came from? If I remember correctly, UIAA changed all the rope testing in the early 70s. Earlier fall testing was in 2 categories, single ropes and double ropes. Both only had to hold 1 fall to pass. Singles with 80 kg and Doubles with 40 kg. After they revamped the categories, all ropes had to survive 5 falls. Singles with 80 kg and Half ropes with 55 kg. Twin rope testing came a little later. I was under the impression the test mass was changed so both types of rope would have a similar strain. Single ropes were typically 11 mm and Doubles 9 mm. Given the cross sectional area of each, 55 kg is more appropriate for the test.