Carabiners
Every piece of protection you place, every anchor you build, every rappel you set up runs through a carabiner. You will own more carabiners than any other piece of gear, and you will use them constantly. The good news is that once you understand what the different types are for, choosing becomes straightforward.
| Use | Carabiner type |
|---|---|
| Belaying and rappelling | Large pear-shape (HMS) locking carabiners |
| Anchors and securing | Asymmetric D locking carabiners |
| Sport-climbing quickdraws | Asymmetric D carabiners with any gate type |
| Trad-climbing quickdraws | Asymmetric D carabiners with wiregates |
| Pulleys and hauling | Oval locking carabiners | Gear racking | Go for lightest and most comfortable |
Carabiner anatomy
The photo shows a labeled carabiner. Here's what each part actually does.
Spine - the long solid side opposite the gate. This is where the strength lives. Under load, most force transfers to the spine, which is why the strength ratings stamped here are highest in the lengthwise direction. It's also where you'll find UIAA and CE certification marks.
Gate - the spring-loaded side that opens to accept a rope, sling, or bolt. The gate type determines weight, cold-weather performance, and whether the carabiner can accidentally open under load. More on gate types below.
Nose - where the gate latches when closed. Keylock noses are smooth and won't snag on bolt hangers or gear when you're cleaning a route. Worth caring about if you climb sport.
Rope basket - the wide curve at the top where the rope runs. The curve is large enough to minimize wear on both the rope and the carabiner itself.
Runner end - the smaller bend at the bottom, where the anchor, belay loop, sling, or quickdraw sits. Smaller because that end doesn't need the same rope-friendly radius.
Carabiner shapes
Asymmetric D - the most common shape on modern racks. Slightly shorter on the gate side to save weight, with a larger gate opening than a regular D. The inside room is a little tighter, but for clipping bolts, racking gear, and building quickdraws, this is the default choice. The lightest wiregates in this shape are what I reach for most on alpine terrain.
D shape - the strongest shape because the geometry shifts load toward the spine and away from the gate. A smaller D can match the strength of a larger oval. Larger gate opening than ovals. Good all-rounder, slightly heavier than asymmetric D.
Pear (HMS) - wide, symmetrical top that works well with a Münter hitch and gives belay and rappel devices room to move correctly. This is the shape you want on your belay loop. Heavier and more expensive than other shapes, but not something you're buying in bulk.
Oval - the original shape. Symmetrical top and bottom curves keep loads centered, which matters when you're using pulleys or building a crevasse rescue system. More gear-holding capacity than other shapes, useful in aid climbing. Heavier and weaker than D shapes, but for the right job, nothing else works as well.
Gate types
Straight gate - solid, strong, easy to use. The standard on the bolt end of quickdraws and for racking gear. Most have a keylock nose.
Bent gate - concave shape makes clipping a rope fast and intuitive. Found on the rope end of quickdraws. Not for racking or anchors.
Wiregate - a loop of stainless steel wire replaces the solid gate. Lighter, larger gate opening, and less likely to freeze in cold or wet conditions. Also less prone to gate flutter during a fall, which matters more than most people realize. This is what I use for alpine quickdraws.
Locking systems
Non-locking carabiners are for clipping protection and building quickdraws. Locking carabiners are for everything where accidental opening would be a problem: belay device, rappel setup, anchors, critical placements.
Screwgate (manual lock) - you screw the sleeve closed by hand. Simple, reliable, light. Requires the habit of checking it's actually locked, which is easy to forget. I use screwgate asymmetric Ds for most anchor and belay work.
Auto-lock - locks automatically when the gate closes. Requires two or three actions to open, depending on the system. Slower to operate but removes the habit dependency. Petzl, Edelrid, and Grivel each have their own mechanisms with slightly different feel. Try a few before committing to a brand.
A note on accessory carabiners: the small ones on chalk bags and shoe loops are not certified as PPE. Most are not rated for climbing loads. Don't mix them into your rack, or on your harness.
Carabiner size, weight and strength
Larger carabiners are easier to handle with gloves, easier to clip under stress, and hold more gear. Smaller ones save weight but become frustrating in cold conditions. Gate opening is the spec worth checking: too narrow and clipping becomes a fight, too wide and the geometry feels loose. There's no universal ideal, which is why handling carabiners in a shop before buying a rack's worth makes sense.
Strength ratings are marked on the spine in three directions: lengthwise (major axis), sideways (minor axis), and open gate. All certified carabiners are strong enough when used correctly. The open gate rating is the one that should make you think about locking systems, not the lengthwise number.
Buying used
Carabiners are one of the more forgiving secondhand purchases in climbing gear. Unlike ropes, you can actually inspect them. Look for deep grooves on the rope basket (rope wear), cracks or sharp edges anywhere on the body, a gate that doesn't snap shut cleanly, and any signs of a hard fall or impact. If the spine is visibly bent or the gate action feels off, walk away. Otherwise a clean used carabiner from a known source is a reasonable buy, especially for building out a rack.
More: carabiner history
Grivel's piece on carabiner history is worth a read if you want to understand how the hardware evolved and why modern shapes look the way they do.
