Cut Resistance of Climbing Ropes Analysed

so how bad do you think
this carabiner is?

it's really bad... it's super super sharp

super super sharp?
it's not only a little bit worn out

it's super sharp

where did you got it from from?
from a crag

so this is a real carabiner
from real crag

yes, there was an accident
in this crag

and the climber...

died...

as you can see it's really sharp

I want to feel it

it doesn't feel that sharp for me

i mean it's not a knife

yeah yeah yeah

but like for a rope this is enough

good to know...

right

i don't know about you

but personally i never had to witness

anybody completely snapping his or her

climbing rope

during a real climbing fall but

unfortunately it happens

so

people who watch my channel

and have fear of falling

watch this video and they will have more

fear of falling after it

now if you're one of these more

sensitive people don't worry just

imagine me holding your hand as i guide

you through this video and everything is

gonna be fine. Okay jokes aside this is a

part two of my conversations with rope

experts from Mammut, where in a part one

i showed you how a soft spot in your

climbing rope can easily end up in a

broken sheath on a realistic climbing

fall we broke the sheath after two falls

and you said it's gonna last

something like this

unfortunately i've seen this way too

many times the good news as we saw in

that video that even with completely

broken sheath the rope was still hard to

snap

*the bad news is that the core strands

are way easier to cut

somebody said of course it's easy to cut

when you use a swiss army knife so this

is not a swiss army knife it's actually

quite dull this is 80 kilograms and this

is a rope

okay that was not that hard

let's get rid of the sheath

okay so now the climber is hanging only

on core strands let's see how

hard it is to cut

the core strands

so if during the fall you would lose

your sheath and then your rope would run

across a sharp edge

so assuming that you take care of your

rope and it's in a good condition

then you still have to quite often

overlook dangers

so first

is all the equipment that your rope goes

through

[Music]

oh

so this was a new quickdraw before i

did that and as you can see the paint at

this point is already wearing off and if

i would continue doing that or i would

just go climbing and take falls on this

quickdraw this part would develop a

groove something like this

or in some cases even worse so a little

groove after some time of climbing is

definitely normal and usually it's not a

problem since the rope makes it nice

smooth and round

usually but not always

like in the story where the climber died

the situation was like this the route

was traversing under the roof and the

crux was after a second quick draw

that's where everybody kept falling and

this quickdraw probably had a nice and

round edge

however this quickdraw only seen a

sideways motion sideways friction from

the rope and nobody ever fell on it

until one day a climber took a fall

and his rope was cut on this quickdraw

do you test how your ropes are resistant

to cutting and are there any standards

start with the second question first so

and no there are no standard tests for

the cut resistance i mean in the

standard today this default test which i

think everyone has seen a million times

but here the rope falls over a clamp

that's very similar to a new carabiner

so to demonstrate how bad a sharp

carabiner can be

we took a brand new rope and rigged a

realistic fall scenario

this is 9.5

grand euro

oh

first of all brand new rope

entire sheath of the rope got wrecked the

force in area is really it's nothing

hard i'm actually shocked by this like

this is crazy. Now we change to the one

the old rope

let's see what happens if your rope is

actually fuzzy and old so we take the

same old rope we find another spot which

is quite fuzzy it's

definitely people would still climb on

this

soft

but not completely bad

will it snap no you think it will not

snap

how many lives the quarter will lose

two strands will be snapped of the core

okay, and the sheath. Okay his guess is

two out of eight

so half of the core's strands snapped, so

on the old rope half

of the strands snapped

on the new one none

[Music]

it's still good to know that even the

old old rope kind of survived but if the

fall would be bigger a little bit bigger

i mean then it would snap be careful

with sharp edges

a couple of years ago UIAA tried to

implement a cut resistant test where the

rope had a dynamic fall over a sharp

edge i think it was a year or two on the

market and then it they cancel it

because the

testing it did not work

now yeah hillary they have their own

test method and we are also looking into

this actually since a long long time the

rope takes a dynamic fall over a granite

edge and slides over this granite edge

so at the moment it's up to the brands

themselves to do their internal testing

there is no

universal standard correct it will come

one day so now the climber is hanging

only on four strands of the rope and we

are gonna show how much it takes to

completely snap the rope if you just

barely touch with the knife

it's crazy

it's just nothing yeah he barely touched

with the sharp edge and it snapped yeah

this is the

the carabiner we did the test with now

it doesn't feel like a knife but the

groove is very deep it's definitely at

the edges it's sharp

but it's

not something that i would expect out of

snapping the rope like that so please

take care of your carabiners and if

you're climbing on fixed carabiners

make sure to check them as well

it's a deep groove but somehow i was

expecting an a sharper edge to be honest

because it still feels kind of smooth

good to know

good to know definitely

so in addition to ropes chewing through

your quick draws you should also be

aware how and where you clip your quick

draws for example this one the rope

should be only clipped to the blue

carabiner and if you don't know why you

should watch my master class on quick

draws let's say for whatever reason i

want to connect myself to the bolt using

a quickdraw if i would do this

this is actually a really bad idea

because the bolt can leave a sharp cut

on this carabiner and this carabiner

later will get in contact with the rope

so instead of that

do the opposite

the carabiner which is designed to go to

the bolt goes to the bolt and the rope

and goes to something soft there was

also for example an accident in

switzerland in mountain guide aspirant

courses one mountain guide lowered two

person on one strand 8.7 millimeter

diameter he lowered them

both on this single strand and then like

one and a half meters below his feet

there was like an edge but really like

we we had a look at it it was not a

sharp edge i would say it's it's just

like a normal edge which you find like

in every direction, you are scaring my

viewers the whole rope um got got cut and

this brings us to a second danger for

climbing ropes

sharp rock formations so if you're a

sensitive person now it's a time to hold

my hand

so the climber actually survived

and this is an old video posted by

british mountaineering council

and i guess the clip speaks for itself

do you have any statistics on accidents

that happen due to snapping climbing

rope so the best statistic that i know

of is the one from the german alpine

club they actually kept the register

of all the rope accidents that took

place i think was for the last 60 years

there they have

53 cases where they know

why

the rope broke and what's the most common

cause sharp edges sharp edges

66 percent

so when the fall happens and you swing

over the sharp edge either you take a

fall over a sharp edge or you're lowered

over a sharp edge or you're

you know you're taking some kind of

swing over a sharp edge but it's not

only the rock formation it can also be

due to carabiners sharp carabiners or

other

metal objects and speaking of statistics

i asked my instagram followers to send

me stories pictures videos about rope

damage and while i got no complete snaps

i got this one

which looks like it got a lot of

abrasion and this one was hit by a rock

with just few strands left and this is

my favorite one it was actually a brand

new rope only three falls and the owner

claims that there was no sharp edges and

the quick draws were fine the only catch

with this rope was 8.9 millimeters

thickness only do you see a difference

in cut resistance among thicker ropes

versus thinner ropes oh yes so i mean if

you want a higher safety margin i mean

the thicker the rope is the better so

how much safer is let's say 9.8 rope

compared to 9.5 or 9.2 so turns out

Mammut already did the testing on this

where we use the same sharp carabiner

and checked at what fall height the rope

will snap and these were the results so

we had all heights up to five meters and

we tested like different rope diameters

and

like a half and twin rope and to no

surprise thicker ropes perform better

with double robes being the safest and

this actually brings me to a current

trend where people buy ultra skinny

ropes thinking that they are the best

maybe if you're not at that level where

it's like so so important for you every

gram every little millimeter of the rope

maybe it's not

important to buy the thinnest rope you

can on the market i mean if you can

i would recommend having two ropes now

you have the the thicker one for for

working out the routes and one you can

also

use when you know how you feel like oh

this route could be a little bit

sketchy there with some sharp edges then

you take the thick rope and then you

have a thinner rope which you might use

when you

already checked out the route and you

want to have a really good goal in

sanding the roots so this video is not

sponsored but a little disclaimer is

that i got these ropes for free from

Mammut and i have to say that climbing

my hardest projects on this ultra skinny

9.0 rope was really nice

however for anything new unknown my

go-to rope is nine and a half

millimeters thickness

and if i would have to choose just one

rope to own this would be it and i guess

if i would be climbing in some sketchier

places or i would be

heavier i hope not maybe i would

consider even thicker rope than that

it's pretty obvious that falls like this

should be avoided at all cost but in

general if the rope is running across a

sharp edge

soft dynamic delaying is actually very

important because if the belayer takes

really hard that increases the peak

force on the rope and also the damage

will be concentrated on a smaller area

of the rope so more things to go wrong

okay let's change gears you guys asked

me what about unicore rose sounds almost

like unicorn so a unicore rope has its

core and sheath strands kind of hooked

together so this is not a unicore rope

and if i would pull the sheath

you can see that they are completely

independent and this would not happen on

unicore ropes if a rope is developed

well the sheath and the core are

perfectly matched together so they can

move very well why don't you hook them

together i saw some brands doing that is

there any benefit of doing one or other

way you can do this but nowadays the

ropes are so well designed that

for example sheath slippage does not

occur that often anymore actually

on most of the ropes not most on all of

our ropes we have a sheath slippage of

zero and this is without intertwining

the sheath with the core what does it

mean zero shift slippage if you

pull the rope over an edge back and

forth how much the core

would move to one side or the other but

if it stays in place then it's well

balanced yeah i've seen some ropes lose

the core in the ends of the rope yes the

ends get completely soft yeah so this is

actually what sheath slippage is is that

the core and the sheath

don't move at the same pace basically

so your ropes don't do that

so as i understand intertwining the core

with sheath doesn't add much benefit for

sport climbers

however if you are ascending a rope

let's say you marrying a rope and your

sheath gets cut

it can

slide down

kind of

well it can slide down

here

this can happen

but this sliding would not happen on a

unicore rope so yeah i don't know if i'm

missing some benefits of unicore ropes

for sport climbers let me know i'm super

curious all right i hope that your fear

of falling is under control and maybe

you even learned something

and i'm gonna release more interviews

with Mammut engineers about some more

geeky topics about climbing ropes and

that's going to be exclusive for people

who are supporting my channel so if you

are interested in that or you just want

to support me consider visiting my

website and thank you so much and thank

you Mammut for inviting me and i hope

to come back one day why is that why

some ropes get stiffer and softer well

to answer that question like textiles is

a very tricky and moody raw material to

work with moody it's very moody