The carabiner is the link between a rock climber and their protective hardware, rope, and accessories. It is a reusable aluminum alloy “hook” featuring a spring-loaded gate that opens inward and automatically snaps closed when released. Most high-quality carabiners designed for recreational use are made from aluminum alloy, which offers an excellent strength-to-weight ratio.
Basic Carabiner Shapes
- Ovals have both advantages and drawbacks. When loaded, the pressure is shared equally on both sides of the biner. Thus, the gate and pin bear 50% of the weight, making oval biners weaker than their more exotically shaped comrades. However, their symmetry makes them particularly useful for aid climbing, as the biner doesn't shift when weighted. They are also useful for building carabiner brake rappel systems and opening bottles.
- D and Modified D biners have an asymmetrical shape that sets the rope closer to the spine. This means the solid spine bears a much greater percentage of the stress than the weaker gate and pin. The D shape provides a large gate opening for clipping the rope or hardware.
- Pear-Shaped symmetrical biners are usually larger with a very wide gate opening. This makes them an excellent choice for clipping multiple items (at belay stations for example). They are often used in conjunction with belaying because they are easy to handle, have a large internal rope capacity, and tend to stay properly oriented along the major axis.
Straight Gate Carabiners are found on biners of all shapes and sizes. This gate is the most versatile of the bunch, and can be used anywhere unless a locker is needed.
Bent Gate Carabiners feature a bowed-in gate that creates a wider opening when depressed. They are generally attached on the rope-end of a climber’s protective gear because the bowed gate and wider mouth make it quick and easy to clip the rope with one hand.
Wire Gates have a stainless steel wire that acts as both gate and spring. Wire gates can be used on either end of a runner, unless they are bent wires, which are used on the rope end of runners and draws. These biners tend to be lighter and easier to clip then straight or bent gates. They are also stronger when inadvertently cross-loaded. They are also less susceptible to the phenomenon of “gate flutter” which can lead to carabiner failure.
Locking Gate Carabiners have a threaded or spring-loaded sleeve on the gate that ensures the carabiner remains closed when loaded, turned, torqued. They enhance the security of biners under constant load and those used with a belay device or munter-hitch. Locking gates can be found on any biner shape, but are most often used on the large pear-shaped variety. Gate designs include screw gates that must be manually threaded, and auto-locking gates that open with a push-and turn. Both are designed to prevent accidental opening.
Nose Notch is the spot where the gate closes against the biner body. Some designes have a small hook or notch at the closure. The keylock or notchless nose design is smoother and less prone to snagging when clipping or unclipping webbing, gear, or ropes.