Carabiners have three main shapes where each shape is designed to suit a different purpose. The three main shapes are the Oval, D-Shaped and Pear. The Oval is often used for Trad Gear;
many people use an oval for racking their nuts as ovals allow the nuts to spin around the carabiners easily so you can select the right nut quickly. Ovals are also good for setting up anchors as they do not tend to shift when weighted. Ovals are generally considered the workhorse carabiner. D-Shaped carabiners are used on quickdraws
because the bottom of the D is smaller, which keeps the sling
from moving around. Pear shapes are generally found on locking carabiners since they have a large gate opening and allow for more to be hooked onto the carabiner.
Locking carabiners are carabiners that include a mechanism that prohibits gates from opening with a single movement. These include screw/twist locks and auto-locking
carabiners. When belaying
always use a locking carabiner. Locking carabiners are also used to connect directly to an anchor and other life dependent purposes.
Screw-gate and Auto-LockingScrew-Gate
Screw-gate locking carabiners must be manually locked by screwing the locking device to the top of the gate. This blocks the gate from being opened by mistake. Some models will have red or orange coloring to indicate to the user when the gate is not shut; this can be a nice feature especially at busy belay
carabiners are spring loaded and therefore automatically lock themselves. The advantage of an auto-locking
carabiner is that you will not forget to lock your carabiner. One disadvantage is that many auto-locking
carabiners require two hands to disengage. Another is that auto-lockers can jam and not correctly close (therefore always inspect your auto-locking
carabiner when using it). They also have a tendency to freeze up quicker in winter, so for alpine and ice climbing you may want to use screw-gates
Non-Locking carabiners are used everywhere that lockers are not: this includes quickdraws,
racking gear, and clipping
gear. The gates can always be opened so it's important to make sure they will stay closed where you use them.
Gate shapes (bent or straight) come into play with quickdraws.
A bent gate will often be used for the rope
end of a quickdraw
to allow easier clipping.
This also makes them easier to unclip
, so make sure to never use a bent gate biner on the bolt end of a quickdraw.
On the bolt end of the quickdraw
a straight gate will be used. Straight gate biners have many more applications than bent gate biners and are usually cheaper.
Wiregate versus Standard
Wiregate carabiners may look weak, but they are generally as strong, if not stronger than standard carabiners. Wiregate carabiners are more expensive than standard gates on average. On a quickdraw,
wiregates are often used as a substitute for the bent gate carabiner (though they can be used for either the bent or straight). Wiregate carabiners are lighter than a straight gate carabiner and have become very popular in the last few years as they allow you to carry more before being loaded down.
Shutter Gate Effect
'Shutter gate effect' (also known as 'gate flutter') is a rare condition created when a carabiner is slammed against the rock. The mass of the gate creates a force which can open the gate. Therefore the strength of the carabiner reduces from the 'closed gate strength' to the 'open gate strength'. A wiregate's gate has less mass and therefore is less likely to open in cases of 'shutter gate effect'.
Carabiners are listed with three unique strengths measured in kilonewtons (kN). These are closed gate (CG), open gate (OG), and minor axis (MA). Closed gate strength is the most important and refers to the strength of the biner when the gate is closed and the forces are created at the bottom and the top of the biner (99.9% of the time). Open gate strength is the reduced strength of the carabiner when the forces created on it are the same as the closed gate, but the gate is open (due to the shutter gate effect or the biner pressed against the rock). Minor axis strength is when the biner has rotated and the forces are pressed against the gate and the spine of the carabiner.