Sunday, 26 July 2009

Choosing Non-Locking, Snapgate Carabiners

Snapgates is a generic term for the non-locking carabiners that form the core of a climbers rack – there are loads of names for them - wire gates, non-lockers, plain gates, bent gates etc.

"Snapgates" covers all non-locking carabiners with either wire or solid gates and these gates can be either straight or bent.

Things to consider:

The most often asked question is wire gate or solid gate….after initial skepticism there is a general trend towards using wire gates; this is based on some solid reasoning together with some misconceptions. A wire gate biner potentially has some key advantages over an equivalent solid gate version, however the devil is in the detail.

The key advantage of a wire gates is that it should be lighter than an equivalent solid gates because the wire gate weighs less than a solid gate. This is a real advantage that has substantially reduced the weight of a climbers rack over the last few years.

Smaller advantages offered by wire gates include increased gate opening and (generally) less likelihood of the gates becoming iced up when winter climbing. The lighter weight of a wire gate also has the potential advantage of minimising gate flutter. Gate flutter sometimes occurs in a fall when the movement of the rope sets up harmonic vibrations in the carabiner, these can - in certain situations - cause the gate to vibrate open and closed. Carabiners are significantly weaker when the gate is in the open position and if a load (the falling climber) is applied to the biner whilst the gate is momentarily open then there is a much higher chance of the biner breaking.

However so much also depends on the design of the carabiner itself and the stiffness of the spring in the gate - I would far prefer to fall onto a well designed, ‘strong’ solid gate biner with a ‘positive’ spring tension than a poorly designed ‘weak’ wire gate with a low/inconsistent spring tension.

There is misconception that wire gates are stronger than solid gates. but in general this is not true. The only exception is in the minor axis test where the extra malleability of the steel wire gate can allow higher readings to be obtained. However this is the least important of the tests and minor axis loading should be virtually eliminated in well designed snapgates – the gate/nose interface is far more important and a far greater source of breakages.

The gate/nose interface – where the gate meets the body is the downfall of many wire gates because the design has been taken straight from its solid gate antecedents. This often means that there is a massive notch where the wire gate sits that is perfect for hanging up on wire/tapes/ropes and loading the biner away from the spine. This is made even worse if the carabiner has a long fat top bar a weak gate open strength and a weak spring. Simple stuff, but there are a lots of poorly designed biners out there - the current Clog wire gates are a good example of how not to build a carabiner.

Generally I would choose a good quality, strong, lightweight wire gate for traditional or winter climbing, but go for good quality, key lock solid gates if sports climbing.
Sports climbing is hard on biners because the steel bolts used to protect sports climbs can chew up the relatively soft aluminium used on carabiners very quickly. A chunky sports draw will last a lot longer than a minimalist wire gate, the key lock nose makes stripping routes much easier and the extra weight is offset by the fact that the draws are often left in-situ on sports routes for red-point attempts. A lot of people also feel that a well shaped bent gate carabiner is easier/faster to clip in extremis than a wire gate.

A lot of people say that carabiners should not be anodised, but there is a very strong case for anodising as long as the anodising is done in an environmentally safe manner. Most climbing carabiners are made from the 7000 series of aluminium alloys because these offer the holy grail of potential high strength and good ductility; however a downside of 7000 series alloys is that they are very susceptible to salt corrosion. Anodising really helps slow down the corrosion process and stop biners from seizing up.

Weight, shape and size are entirely personal and come down to looking/playing with the various options. The lighter modern biners are almost always smaller than their heavier counterparts and you need to choose where to draw the line on a carabiner being too small to use effectively.

Choosing snap gate carabiners – key things to look for:
  • A good gate open strength – 9kn or 10kN. 7 kN is just not enough – there is no margin for error in manufacturing tolerances and it is quite possible to generate 7kN in a fall especially when using a static belay device (GriGri) or a thick, old rope.
  • A well designed body that drives the rope into the spine i.e., no flat long top bars.
  • A minimal notch where the gate meets the nose of the carabiner to minimise the chance of items hanging up on the notch and so loading the biner away from the spine.
  • Check the spring tension – it should be firm and constant without being stiff.

Choosing snap gate carabiners – nice finishing touches:

  • A shrouded nose – helps stop the gate opening accidentally
  • Anodising – help stop the biners seizing up
  • Separate colours for either ends of the quickdraw on wire gate draws. One end of a draw should always be used for clipping gear and one end for clipping the rope – this is because the gear end often becomes marked and notched where bolts or hard materials dig into it under load. These nicks and marks can pull threads on ropes, slings and harnesses. Solid gate draws have a straight gate biner for the gear and a bent gate for the rope – no chance of mixing them up; however wire gate draws can easily be used the wrong way around unless the carabiners on the different ends are identifiably different.
  • Rope groove – helps keep the rope close to the spine.
There is more information on climbing equipment and how to use it on my main website.

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