Carabiner Buying Guide

Introduction

Carabiners are necessary elements of any climbing safety chain. Whether clipping protection, building a belay or simply belaying a partner, the carabiner always has a role to play. Choosing the right type for each use is not just practical, but more importantly, it's also essential for your safety.

Carabiner shapes

Oval

This uniform shape ensures that the load stays centred, thereby helping to avoid the dangers of cross loading. Oval screwgate carabiners are widely used on big wall and pulley set-ups. An oval wiregate is also great for racking nuts, allowing them to fan out evenly beneath the carabiner for easier selection.

'D' & offset D

Adapted from the Oval shape, the original D has a straight back bar and symmetric curves to the gate. The focal point of the load is nearer to the back bar which increases the carabiner's strength slightly. Recently the D has been replaced as the versatile carabiner of choice by a non-symmetric variant, the 'offset' D. Like the standard D shape, this focuses the load along the back bar but a narrower lower section helps make the carabiner lighter. They can also generate a slightly larger gate opening. The angle of the upper curve is ideal for clipping through protection or bolts so this shape is the standard for quickdraws as well as general purpose use.

HMS

The HMS (short for the German “Halbmastwurf Sicherung”) is essentially a very large offset D. The extra size creates a wider and thicker top bar, which allows ropes to run very smoothly. For this reason many people will choose to belay with an HMS carabiner. The extra width and larger gate opening also allows for multiple ropes or knots (like the Munter hitch or two clove hitches) to be attached

Carabiner gates

Straight

Simple straight gates are the classic all round non-locking option. They are commonly used in quickdraws, especially for clipping protection or bolts. Many solid gate carabiners now come with 'keylock' clean noses rather than a notched nose, helping to prevent irritating and potentially dangerous hang-ups where the gate and nose don't engage properly.

Bent

Bent gates give a slight advantage when clipping a rope; the rope is guided into the carabiner's basket by the curve of the gate. Bent gate carabiners are therefore often used on the lower end of quickdraws to facilitate quick clipping. Like straight gates, many bent gate carabiners will have 'keylock' clean noses.

Wire

Wire gates are a lightweight alternative. They use less metal but achieve the same strength ratings. They won't freeze up in winter, and they are more resistant to 'gate flutter'.

Screwgate

Snap gates (straight, bent or wire) make sense for quickdraws where speed of clipping is crucial, but a locking carabiner adds security when belaying a partner or when building belay rigs. Screwgates are the most common form of locking gate and offer great value, but they do rely on the user to remember to do up the sheave every time. Keylock clean noses are increasingly common and help prevent snags.

Twistlock

Automatic locking mechanisms like the Twistlock reduce the possibility that you might forget to lock your carabiner. However they can be trickier to open than screwgates (particularly one handed) and will usually cost slightly more.

Carabiner uses

Belaying

When belaying it's important to use a carabiner with a generous top bar. Small, narrow-angled D shapes can exert too much friction on the rope, making belaying catchy and unpredictable. An HMS locking carabiner is ideal, though it's important to remember that screwgates must be locked manually every time. This explains why automatic locking HMS options are also popular. One of the other dangers when belaying is that the carabiner twists round and becomes cross-loaded across the gate. Specific belay carabiners that capture the belay loop can prevent this from happening.

Belay building

Constructing safe belay positions at the end of a pitch is a skill in itself. Locking carabiners (usually offset D shape screwgates) should be used to connect slings or the rope to protection. You will then often need to bring together a few slings and/or bights of rope into one hub. This central point will often demand a large HMS locking carabiner. The key is to have several screwgate carabiners on your harness to deal with all eventualities.

Racking

Nuts, hexes, cams, slings and even approach shoes will often need to be attached to your harness. Simple snapgate (straight, bent or wire) carabiners are the best way to do this. An oval shape is great for racking nuts.

Quickdraws

What are quickdraws?

Quickdraws are made up of two carabiners joined together by high-strength webbing. When climbing, one carabiner is clipped to a point of protection, for instance a bolt hanger or camming device. This carabiner is usually able to move freely within the sewn sling to reduce the 'pull' on the protection. The other carabiner is clipped to the rope. This end is often secured within the sling by a tight rubber 'tadpole' which prevents the carabiner from twisting, reducing the possibility of cross-loading and keeping it well positioned for clipping the rope. The sling increases the distance between protection and rope (hence why they're often called 'extenders'). This allows the rope to run more freely with less risk of dislodging the protection. ‌

Traditional climbing with quickdraws

For traditional climbs, quickdraws with lightweight wire gate carabiners are the norm. The wire gate is especially useful on winter climbs as it won't freeze shut. Thinner, lighter slings also help cut the weight of your rack on the harness. Carrying a variety of lengths from 10-12cm (short) through 15-18cm (medium) and up to 25cm (long) allows you to manage the line of the rope on meandering trad routes and when crossing roofs. A rack of a dozen quickdraws will usually suffice for most pitches.

Sport climbing with quickdraws

For sport climbs, quickdraws with sturdy solid gate carabiners are the norm. Chunky carabiners put up with constant abuse and regular falls. Wider slings are much easier to hold when working routes and hauling back to your high point. A straight gate makes bolt clipping easy while a bent gate facilitates rope clipping. 10-12cm lengths are fine for most straight-up routes, but it's also worth carrying a few longer sport draws for occasional use. A rack of a dozen quickdraws will suffice for most pitches but long European sports routes might require far more. Guidebooks often give the number of bolts for any route so you can check you have enough before setting off.

How carabiners are made

Climbing carabiners are generally made from aluminium (usually type 7075, an alloy also used in the aerospace industry). This provides a fantastic balance of lightness, strength and hardness.

Forging

For decades carabiners have been built by 'cold forging', whereby aluminium rod stock is bent into the required shape at room temperature. The results are very strong and consistent. However, they lack the finesse of modern hot forged carabiners. Hot forging requires the heating of both rod stock and dies. Hot metal can be moved around by the dies, allowing the creation of more complex and tailored designs. Metal can be concentrated where it's needed and removed where it's not needed. This process allows 'I-Beam' profiles as well as enhanced radii on rope-bearing surfaces and even clean noses on wiregate carabiners. Hot forging can provide lighter weight units with no strength compromise.

Anodising

Once the carabiner has been forged and heat treated, it can be anodised. Anodising thickens the natural oxide layer that covers aluminium alloys exposed to air. This process increases wear resistance and allows the durable application of colour.

Strength ratings

Statistics

Every climbing carabiner is required to display its strength ratings on the back bar. There are three statistics quoted; major axis, minor axis and gate open. ‌ - Major axis strength is measured for a load along the back bar with the gate closed (the normal mode). - Minor axis strength is measured for a load across the gate with the gate closed. - Gate open strength is measured for a load along the back bar with the gate open. ‌ Carabiners are rated in kiloNewtons (kN), a measure of force. It's hard to visualise this dynamic measurement; if your carabiner is rated to 25kN along the major axis, what does that mean? A 25kN rating is roughly equivalent to a 2500kg mass under the influence of gravity. Therefore the carabiner would hold a static load of 2.5 metric tons.

Testing

Every climbing carabiner is required to display its strength ratings on the back bar. There are three statistics quoted; major axis, minor axis and gate open. ‌ - Major axis strength is measured for a load along the back bar with the gate closed (the normal mode). - Minor axis strength is measured for a load across the gate with the gate closed. - Gate open strength is measured for a load along the back bar with the gate open. ‌ Carabiners are rated in kiloNewtons (kN), a measure of force. It's hard to visualise this dynamic measurement; if your carabiner is rated to 25kN along the major axis, what does that mean? A 25kN rating is roughly equivalent to a 2500kg mass under the influence of gravity. Therefore the carabiner would hold a static load of 2.5 metric tons.

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