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Maillons, WHY?


New member
Why do people insist on using fiddly and slow things when biners are so freely available?


Well-known member
A good example would be trying undo a jammed krab at the top of a deep shaft in the snow - say JH at Rowter Farm in February when five people have climbed up on it. You can't go home until you get it undone, as the knots are jammed tight, and it's minus ten with the windchill. Or to make matters worse, a jammed krab at the rebelay in the shaft - I couldn't even get the damn rope up that time, and had to leave it in and someone (probably Al) had to go back with a mole wrench. There's just no leverage on the nut with cold or slippery hands. I always keep a 12mm spanner on my harness gear loop and use Maillons now - remembering to keep them greased up if they're my own!


Krabs are not reallydesigned for cyclic loading, then deform quite a bit when used at pitch heads making them a lot more susceptible to fatigue failure. Maillions when correctly done up don't visibly flex.

Krabs are okay to use so long as you replace them regularly which most cavers are too tight to do.

I have a picture of a 12mm steel bar that failed through fatigue after about 40,000 loads of less than 10 newtons that I can upload if you want, how many times does a krab cycle between 500 and 1000 newtons during a 30m prussic?


krabs on traverse lines can and do rotate into weaker positions.

Likewise, krabs which are used at the top of mine shafts, or pitches where the main Y-hang is beneath a ledge rather than above it, can rotate when a climbing caver gets off the rope.

Both these situations require care to ensure that the krab you've just passed is still correctly oriented. For a variety of reasons, this doesn't always happen - it isn't as important if you use maillons in these situations. (As long as you screw them shut!)

And, of course, sometimes a krab is just too big for a rigging situation.

Chocolate fireguard

Active member
Antwan said:
I have a picture of a 12mm steel bar that failed through fatigue after about 40,000 loads of less than 10 newtons that I can upload if you want, how many times does a krab cycle between 500 and 1000 newtons during a 30m prussic?

For steels there is considered to be a fatigue limit - a stress  below which fatigue will not occur in a specimen that does not already have a notch. This is about half the ultimate tensile stress (the stress at which it will break at once).

The picture may be useful if it clearly shows the face of the broken end, but a description of the geometry when it was cyclically loaded would be more useful. At the moment I am struggling to envisage the situation with the figures you give.


Well-known member
From Wiki:

"Death of Michael Lush
On 13 November 1986, self-employed hod carrier Michael Lush was killed during his first rehearsal for another live stunt. The stunt, called "Hang 'em High", involved bungee jumping from an exploding box suspended from a 120 ft-high crane. The carabiner clip attaching his bungee rope to the crane sprang loose from its eyebolt during the jump. He died instantly of multiple injuries, and the Breakfast Show was cancelled on 15 November after Edmonds resigned, saying he did not "have the heart to carry on".[7] Rumours, denied by the BBC at the time, that Edmonds had been due to resign to launch a career in American television proved incorrect."

(Noel Edmunds Show)

I know personally of another incident when a crab failed on a zip wire at about 30 mph. The unfortunate victim is happily alive and well but was well busted up at the time. I wont kname him but some on here may know him.

I trust 10mm maillons and struggle to visualize any condition where one will fail. I am however aware of the situation with Pezl Stops where the use of one can cause the gate to twist undone.
Hmmmm, I was pretty much adamant about getting the club to change over to Krabs, but I am not so sure now. Bit of research needed.


Staff member
I imagine it is mostly down to cost.  Cavers used maillons because they are something like a third of the cost of even cheap krabs.  That's a big difference when a club or group want to buy enough to rig up a couple of SRT caves or for an exped.

In these more affluent times (relatively speaking) I have heard that many clubs have replaced their maillons with krabs and now have large chains of them hanging unused in the store.

Any kit can fail given the right circumstances, of course, so krabs or maillons is a matter of choice.  Krabs are quicker and easier to use, but maillons may better serve long term rigging.  Both have got thousands of cavers to the bottom of potholes and back out again  :)


Well-known member
I am aware that there are people on here much more expertise than I, but I believe that krab failure is due it it being loaded on the gate, and that if this happens failure is a certainty.


New member
Snap gates spring open, as mentioned in the bungee jump scenario. That's well documented.

Most krabs aren't steel, they're alloys.

How was your 12mm steel bar loaded?

Krabs can rotate, user error, same as not doing up maillions.

Exped and long term rigging are different scenarios to sporting caving so can appreciate the use of maillons here.

If 40,000 cyclic loads of 10N broke your steel bar which was designed to hold 22kN in the direction of your testing, then I concede that point, but to be honest. I doubt it!

Sent from my iPhone using Tapatalk


Well-known member
On a technical trip, Maillon Rapides occupies a much smaller volume in a tackle bag than the equivalent number of karabiners.

I've always liked Maillons because, when they do jam shut, there's the option of using a spanner (or another Maillon) to get them open.

I believe the accident record regarding Maillon use in British caving is pretty good, so unless there's a very good reason to move away from their use, I'd be fairly reluctant to.

What's this about "more affluent" times Badlad?  :confused:


New member
Because we are mainly digging most of our rigging is done with maillons, they are probably going to be in place a fair length of time and many will never be used again. Krabs are a lot dearer to sacrifice.

That said I'd have thought most cavers would have a mix of both, krabs a re quicker and easier for sport trips etc.

In my experience club krabs tend to disappear fairly quickly, not through theft, they just trickle away through "natural causes", and clubs would be better buying maillons.


Our club uses Screw gate Krabs almost exclusively for rigging, there are large strings of maillons sitting in our gear store that simply don't get used due to there fiddly nature and the necessity to carry a spanner.

With regards to the actually rigging on Krabs, Personally I feel that as long as you make sure to actually screw up your Krab, and turn it so it is not loosened by gravity but tightened by it then they are perfectly safe. Rigging on snap gate's is just asking for trouble due to the possibility of them popping open.

Either way its probably best to use what you feel safest with/ know best.

Mark Wright

Active member
In an industrial environment Maillon Rapides are used where a more permanent attachment is required. So long as a Maillon Rapide is screwed up (technically, torqued up) it is unlikely it will undo itself in use. Maillon Rapides are also a lot stronger than carabiners. E.g. a 7mm 'long' Maillon Rapide has a breaking load of 25kN. A 10mm 'long' Maillon Rapide has a breaking load of 55kN whereas a carabiner made with 10mm bar would be around half of this breaking load.

Maillon Rapides are also chosen where there is a possibility of abnormal loading, e.g. rigging a pull-through. Maillon Rapides will significantly deform before failure giving some warning of the potential danger, unlike carabiners.

The example given by Roy Fellows of the death of Michael Lush due to the failure of a carabiner might be a bit misleading. The carabiner which 'failed' was in fact a double action twistlock connector and it was a problem of 'roll-out' that caused the accident and not a failure of the actual carabiner. I do some work with UK Bungee and this sort of problem should no longer exist as they use triple action connectors or correctly torqued Maillon Rapides these days. The Code of Practice for Arborists also reccommends the use of at least triple action connectors due to this roll-out problem.

The name 'Maillon Rapide' means 'Quick Link' suggesting they are quick to install. I suppose it depends on how quick you want to be able to screw or unscrew them.

The cost of Maillon Rapides when compaired to carabiners is important when you consider they are usually around 1/3 of the price of even the cheepest alloy carabiners. This is an important aspect particularly where they are used in a club environment. If a club tackle master thinks its hard keeping track of 7mm 'long' Maillon Rapides, think how difficult it would be if they had nice alloy carabiners in their tackle store. They wouldn't be in there for long as Bottlebank has already mentioned.

As Badlad has said, people have been using Maillon Rapides for rigging caves for over 35 years without any problems and it really boils down to personal preference. Most trips that I've been on to the Berger have used Maillon Rapides for all the rigging but when the French rigged the cave in 2013 for the International Expedition they used mainly carabiners. Pitlamps comment on the volume taken up in your tackle bag is also an important one, particularly if expedition caving.

If caving anywhere other than a UK 'P' bolted cave everyone should always carry a spanner in order to check the hanger plates which are the most likely thing to loosen.   



Well-known member
Forgive my ignorance, Mark ? but what is a 'triple action connector'?

(As for 'quick links', as I understand it they were originally produced for industrial applications, in particular joining chains ? so I guess that an MR is a lot quicker than welding another link in a chain.)

Mark Wright

Active member

Maillon Rapides were indeed originally designed to make a 'quick' connection for linking chains.

A snapgate carabiner is a single action connector, i.e. open the gate with one single action.

A screwgate/twistlock carabiner is a double action connector, i.e. unscrew or twist the gate (one action) and then open the gate (double action).

A triple action twistlock connector requires 3 actions to remove it, i.e. push the gate up (one action) then twist the gate (second action) and then open the gate (third action).

I have seen 4 action connectors where there is a second pushing up of the gate after it has been twisted.