Down-to-Earth Rope Longevity Experiment
By Sean Cleary (cleary (at sign) scisun.sci.ccny.cuny.edu)
Copyright by Sean Cleary, cleary (at sign) scisun.sci.ccny.cuny.edu, permission granted
to reproduce electronically for noncommercial purposes only.
A discussion of rope longevity has prompted me to describe a simple
experiment from a few years ago, when some of my partners and I decided
to see how much my workhorse lead rope had deteriorated. The rope was
three years old at that point and was about at the point where it
should be retired as a lead rope and relegated to toproping/seconding
use. That is, it had become fuzzy along most of the length of the
sheath and was particularly worn and soft at the ends where the figure
eights were always tied.
We decided to reproduce the high fall factor tests used by the UIAA
as part (and only part) of their certification of new ropes. We didn't
have any simple means of measuring impact force, which we would have
preferred, but instead just decided to keep subjecting the rope to
very high fall factor falls until it broke. That is much easier to do
and lots of fun besides.
We found a suitable object, a large piece of pipe, which weighed about
70kg. This is a bit lighter than the normal UIAA 80kg test weight, but
it was pretty convenient and is well more than what I weigh with a nice
heavy rack and pack full of gear. We tied three harnesses for the pipe
out of 1 inch tubular webbing and tied the pipe's harnesses to the
"leader" end of the rope with a figure eight follow-through.
The piece of rope we used was a little more than 15 feet long and was
hacked off the end of the lead rope. This was the most worn piece of
rope; it was very soft and the sheath was completely fuzzed over. With
the 8's tied in the ends it was about 13 feet long.
We anchored the other end (the "belayer" end) of the length of rope to
a steel and concrete pedestrian bridge. We looped webbing around the
bridge and tied the other end of the rope to that loop with another
figure eight follow-through.
We used another rope and a pulley to hoist the pipe above the anchoring
point at the bridge to a point as far above the bridge as we could.
Thus, we were trying to drop the pipe 26 feet on 13 feet of rope: a
factor 2 fall and in principle, the most severe fall that should ever
arise in a climbing situation. A fall factor 2 could arise in a
climbing situation if for instance the leader climbs up from a belay
ledge then falls fully past the ledge before placing any intermediate
Here's what we decided to do:
Before drop: After drop:
+13' ] o <= pipe ]
] | ]
] | ]
] | <= rope ]
] / ]
anchor] 0' anchor]\
] ]| <= rope
] -13' ]o <= pipe
Pulley and hoisting rope omitted for clarity/irrelevance.
The rope held four severe falls. The first fall was actually greater
than fall factor 2. The anchoring webbing was inadvertently pulled
tight when we were hauling the pipe upwards for the first drop so we
dropped it about eight feet further than the 26 feet we were aiming
for. So that was really a fall factor 2.5 or so. The subsequent four
falls were fall factor 2 and on the fifth fall, the pipe fell to the
ground. Actually the webbing that held the pipe broke, even though it
was triply redundant. The harnesses were cut at the somewhat sharp
edge of the pipe. But nevertheless, the rope was pretty much destroyed
by that point. The sheath was completely gone at the end of the bight
on the figure eight on the anchor end and most (say 80%) of the strands
exposed there were cut. There was a sickening smell like that when you
cut the ends of webbing with a hot knife. The harness end figure eight
has been impossible to undo!
Overall, I was pleased that the worn rope held a succession of very
severe lead falls.
Things to think about:
You may have to hunt around to find a suitable place to do this. I
would not recommend doing this in a climbing area since you may be
likely to make a mess/ scar the wall/ break off holds when the rope
does break. Also, you don't want to stress a piece of protection that
severely unless it's really the security of the piece that you are
interested in studying, not the piece of rope. And you don't want
to leave a massively stressed-out bolt where someone else may be
likely to want to use it for their own security.
The fall was held by a figure 8 tied directly to a bombproof
anchor. That was where the rope almost broke. In a normal climbing
situation, that would have been held by a belay device and thus been
more of a dynamic connection point. It would have been significantly
more dynamic if the belayer had body weight as part of the belay
chain. We didn't get any volunteers to hang out below a massive
falling pipe and belay it, though. You'd get jerked around quite
a bit and you'd want a pretty serious helmet for that pipe...
I didn't realize that during the UIAA tests, they allow the
unweighted rope to "relax" for a few minutes between next drops. We
didn't allow any time for the rope to relax. In fact, after each drop
the pipe dangled spinning on the end of the rope for a few minutes
while I checked the rope and knots. So the rope was only unweighted
when we were hauling the pipe upwards, which was not very long at all.
Evidently this "relaxing" period is significant as it allows the fibers
to return to their normal lengths and it allows the kern to cool
This was the softest and most worn segment of a reasonably worn
rope. The part near the end takes a great deal of stress from falling
since at that point, the climber is tied in and the knot gets very
compressed in repeated falls.
The rope probably elongated after each drop. We didn't measure its
length between drops but we were of the general opinion that the rope
was getting a bit longer each time. It also seemed like a sharper
stop each time but again, that was merely our opinion. That would
be consistent with my limited understanding of how impact forces are
likely to rise as the kern of the rope is damaged further.
The UIAA falls are actually not quite factor 2 falls, more like
factor 1.8. The UIAA is a bunch of engineers in a laboratory with
equipment meant to study and certify climbing equipment under
controlled circumstances who do this for pay every day; we are a bunch
of mathematicians and molecular biologists who decided to drop a pipe
off a parking garage early one Sunday morning out of curiosity and
comedy value. I'd take their opinions and conclusions more seriously
- This is a sample size of 1. Your mileage may vary. We did this
experiment principally out of curiosity and that is all that our
experiment was meant to satisfy. Your rope is different from that
one; it has a different history and care. Nobody can say whether or
not your rope will break under any circumstances with great certainty.
I would recommend doing this experiment yourself for the following
5m/15' of rope isn't that much off of an old 50m/165' rope. There are
still plenty of times that all you need is a 45m/150'
rope particularly in alpine or toproping situations. And if the
ends are worn, what were you going to do with them anyway?
It is kind of a weird feeling to set out one morning determined
to break a piece of rope that you have maintained and trusted for
It is pretty incredible to see the rope hold a very severe fall.
The rope was an Edelrid 11mm with a dry treatment. It had been used
for three years on regular weekend use and plenty of longer trips, for
both cragging and alpine routes. It had never taken a lead fall of any
length but had taken many toprope and seconding falls. Its dry
treatment had long disappeared and it had been cleaned regularly. It
had been soaked thoroughly by gritty glacial snow, rappelled on in
thunderstorms when wet and dirty, and it had been dragged across soft
sandstone and through dirt-filled granite cracks, etc. When new, it
was rated for 6 UIAA severe (fall factor 1.8) falls. So I was pretty
happy when it held 4 even more severe falls after 3 years of regular
Next time we're bored, maybe we'll see just how well TCU's actually hold...
Sean Cleary cleary (at sign) scisun.sci.ccny.cuny.edu