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Grivel Sigma K8G Carabiner

Sigma K8G

Rating

My vote: None ( 4.1 avg )

Description

Versatile carabiner with gate-wire Twin-Gate system.

The Sigma is a D-shaped carabiner and sees its prevalent use on belays, at personal anchor systems, and it can be used also in the quickdraws to clip the rope when you want to guarantee the total non-opening of the carabiner itself under stress from a fall in a hard pitch and with long protections and high risk of falling. Opening by Twin-Gate wire-gate system, which does not require any additional maneuver (e.g. screwing), making it safer and faster than other systems. Furthermore, it allows to avoid accidental openings that can occur for example due to contact with the rock, due to incorrect passage of the rope due to involuntary hand pressure. Two openings also allow greater resistance than one. Finally, it maintains its functionality over time and does not fear the presence of dust, earth, ice like other systems. The gate-wire combination facilitates its use even with gloves, and allows you to easily attach all types of devices (brakes). Individually tested, with the date of testing and progressive number laser-marked on it.

Retail price

US$ 14.99

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Weight (g)

Weight (g)

In grams, the weight, as stated by the manufacturer/brand.

57 g
Shape

Shape

Rule of thumb

Almost every carabiner you use will be non-locking offset D’s, with the exception of a Pear/HMS locker as your belay ‘biner.

Offset D (aka Modified D)

60% of the market

A modification of the standard D shape, the top of an offset D is much wider, allowing for a larger (and superior) gate opening. When loaded, most of the weight is transferred to the spine of the carabiner making them stronger than most other shapes. Used for top and bottom quickdraws, as racking carabiners, and lightweight lockers.

Pear / HMS

22% of the market

The Pear/HMS carabiner is used primarily for belaying and/or setting a powerpoint in an anchor. The wide top means they can hold a lot of gear. They are almost always locking and are generally heavier (than D/offset D's) because they need more material to gain back strength lost due to their shape.

Oval

8% of the market

The first carabiner shape to be mass produced. When loaded, the pressure is shared equally on both sides of the ‘biner. Since the weaker gate shares the load with the spine, oval biners aren’t as strong as shapes that direct the load to the spine. The bonus is, your gear rests squarely in the middle, so it's great for holding nuts, pulleys, and prusiks.

D (aka symmetric D)

7% of the market

D’s have a symmetrical shape that sets the rope closer to the spine, putting the load on the spine (versus sharing the load with the weaker gate side, like the oval). Since the strongest part of the carabiner carries the weight, D’s are the strongest shape. Downside: Smaller gate openings than the offset D.

Quick Link (aka Oval link, Maillon Raptide)

1% of the market

Although most climbers wouldn’t refer to this shape as a “carabiner” they are certified by the same EN standard as all the other carabiners. These semi-permanent links ensure the gate will not accidentally open. They're used when setting up a semi-permanent rappel station (not used while climbing up).

Semi-Circle / 3D

less than 1% of the market

Semi-circle: Mostly used by Search and Rescue as this is a great way to secure a chest harness.
3-D: Designed to increase the gate opening and to reduce the chance that the rock will rub your rope and/or the locking gate open. Buy if you’re the curious type; they’re not cheap, and there’s not many in the US.

Learn More

Pros and cons of each shape, graphs and more examples
D / Offset D
Locking

Locking

main non-locking carabiners uses:

  • quickdraws
  • to rack (hold) your gear on your harness
  • part of an anchor setup

main locking carabiners uses:

  • belay carabiner
  • main anchor powerpoint
  • when you need the gate to stay shut

screw gate vs auto-locking gate

Screw gates are generally lighter and cheaper.

Auto-locking gates are usually considered safer as they automatically snap shut, not counting on one's memory to close and are harder to accidentally unlock. The debate comes on opening speed as some are much faster while others can be a struggle.

Learn More

See the newest auto-locking gate technologies
Auto - 2 action
Straight or Bent

Straight or Bent

It's easier to see the difference between straight and bent gates on solid gate carabiners:

Straight Gate

The standard. Always used as the bolt-end of the quickdraw, and still sometimes used on the rope-side too. Also used for racking gear such as cam and nuts.

Bent Gate

Created to make it easier to put the rope into a quickdraw with their larger gate opening. Primarily used on the rope-end (bottom) of quickdraws.

Extra Notes

  • Choosing a bent or straight gate does not significantly change the weight, strength, or price of the carabiner.
  • All locking carabiners have straight gates.
  • Today, many wiregates have a hybrid almost-straight-but-kinda-bent gate and are offered in this version only (not as a classic a bent or straight option). We have classified these as bent gates since they're not totally straight.

Important Note

Many manufacturers are now making the bolt-end carabiner come standard in silver (to match the bolt color), and are coloring the rope-end with other anodizations.

Do not mix (interchange) bolt-end carabiners and rope-end carabiners. This can be very dangerous as small abrasions made by the bolt can easily wear your rope. DMM put out a great video/write-up on this issue.

Bent
Full Size

Full Size

Full size carabiners are easier to hold but generally they're also heavier.

This is a totally debatable field as there is no official size, weight, or gate opening necessary to be full size. There are no certifications and this isn't a standard the manufacturer's normally describe specifically.

We did our best to compare (descriptions, in-person use, etc), as a way to help give more information about this carabiner. Like always, if you see something that seems totally off, send us a note.

Yes
Keylock

Keylock

A keylock nose means the nose is smooth. Keylock carabiners are also known as: snag-free, notch-less, and hook-less.

Keylock Benefit

The lack of a hooked nose makes for less snagging on gear and bolts – a dramatic improvement.

Keylock Drawback

Given that they’re more complicated to manufacture, keylock designs often come at a higher price, especially in wiregates.

Worth Considering

There are more design features necessary to guarantee a snag-free experience, like the curvature of the nose. Some keylock carabiners will still catch on the nose because of the lack of a smooth nose arc (smoother the arc, smoother the clip).

Learn More

Check out our blogpost that goes over carabiner nose design to get all the details
Yes
Solid or Wire

Solid or Wire

Solid Gates

Generally on beefier carabiners, so they're usually heavier and more durable. They can also feel more substantial in your hands while clipping. Often favored by sport climbers.

Wire Gates

Featured on the lightest carabiners, so they're favored by trad and alpine climbers.

Some considerations

If you want keylock nose carabiners, then solid gates will be much cheaper compared to wire gates.

When wiregates first came out they were not trusted (too new, looked too simple). Now, it's proven that wiregates have less gate flutter and gate shutter than solid gates.

Learn More

Compare gate flutter and gate shutter
Solid
Gate Opening

Gate Opening (mm)

Gate opening refers to the distance between a carabiner’s nose and the fully open gate.

General Guidelines

top of your quickdraw: 17 mm – 22 mm
bottom of your quickdraw: 23 mm – 26 mm
as an anchor holding webbing/gear: 19 mm+

Adding bias towards a larger gate opening is a great option once you’ve narrowed your choice to a few similar carabiners and need help determining which one is the best.

Learn More

Gate opening comparisons, examples, averages, shape, sizes, graphs, and explanations
23 mm
Number of Colors

Number of Colors

The number of different colors that you can find this carabiner in. This color-coding practice was started with just 2 colors, usually silver (that goes on the bolt side of a quickdraw) and another color for the rope side. Now, carabiners come in 5+ colors sets known as "rack packs" so your carabiners can match your cams.

Climbers can also match their carabiner color to their harness or other gear just for fun.

Learn More

Carabiner Rack Packs Explained
1
Lock Indicator

Visual Warning

A lock indicator is a visual warning only seen on locking carabiners. It adds some sort of visual to show if the carabiner is unlocked such as the color red, a danger sign, an unlocked image, etc. When the carabiner is locked the visual indicator is hidden.

Only a small list of manufacturers add this safety feature, although you can easily add one yourself with a permanent marker.

No
Strengths (kN)

Strengths (kN)

In kilonewtons, the strength, as stated by the manufacturer/brand.

Major Axis Closed Gate Strength

This is the strongest orientation and the way carabiners are designed to be loaded.

Major Axis Open Gate Strength

This strength is measured because while climbing, carabiners lying against the rock can be opened slightly as they move across an uneven surface. A carabiner can also open slightly during a fall as the ‘biner starts to vibrate, dispersing the energy (also called "gate flutter"). A weak gate closure (due to a poor/failing spring or an over-stressed wire) could also leave the gate ajar.

Minor Axis Gate Strength

Carabiners are not intended to be loaded along the minor axis (cross-loaded), but it is possible for a carabiner to unintentionally rotate during use, especially while belaying. Of all accidental misuses of a carabiner, cross-loading is the most frequent suspect, which is why there is a rating for it.

Generally wire gates are stronger than solid gates in the minor axis. During the test, the wire gate bends, absorbing some of the force, as compared to a less pliable solid gate.

Learn More

How carabiners are rated, recommendations and strengths.
  30 kN   9 kN    9 kN

No reviews yet.

WeighMyRack Gear Review in-depth technical review

I’ve seen a lot of online debate contesting the usefulness of this carabiner, the naysayers claiming it’s a “gimmick” and a “solution to a problem that doesn’t exist.” Many folks are excited about the new innovation albeit a little hesitant to commit.

I agree that this debate is most similar to the question of an ATC vs GriGri. Is it necessary that everybody change over their locking ‘biner fleet immediately? No. Do Twin Gates assist in reducing risk? Yes. Is it worth consideration when buying lockers in the future? Yes.

The Alpine Start Gear Review no rating given just a review

The Twin Gates are an interesting take on the locking biner concept. They work, and they work well. They can be finicky to operate, even for an experienced user, but by far their biggest downfall is their biggest upside: innovation. Someone who’s gotten used to the idea, or is curious about new gear, will learn to use them quickly and effectively. But pass them to your partner on a multi-pitch route and they look at them with distrust. It’s a great concept, it really is, but it will take a while for the general climbing population to become accustomed enough with the Twin Gate system for it to be widely adopted. For those willing to try something new, prepare to be questioned.

Climbing Gear Reviews UK rating 5/5

The combination of solid and wire gate was much easier to operate and after a short period of familiarisation became pretty much second nature. How much did I like this carabiner? Well I went out and purchased another two with my hard earned pennies and I’ll happily buy the Plume when it becomes available. In use it was quicker to set securely than a standard screw gate with no risk of forgetting to screw it up and there was never a risk of it freezing shut even when getting dripped on at a (semi)frozen, icy belay. Is it the perfect locking carabiner? Not quite. There is a familiarisation period or ‘learning curve’ before you feel totally happy with them and they are a little trickier to unhook from rear racking loops on your harness. There are some placements when it’s a bit trickier to ‘hook’ the outer gate than a standard carabiner, such as a deep set wire where the loop has dropped into the crack, but it’s not a deal breaker especially as I tended to use them mainly on the rope end of extenders/slings. Something I didn’t consider however is that you may be totally happy using your shiny new twin gates but your partner may not! After we swapped leads for the final pitch of Crest Route in SCNL I had to suppress my laughter as cries of ‘Witchcraft!’ assailed me from above as Bruce endeavoured to open a twin gate I’d passed to him on a long sling!

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The UIAA equipment standard provides a baseline for equipment performance in a test lab under controlled conditions on new equipment. Although these test conditions are relevant to the conditions encountered climbing, conditions encountered at the crags and the condition of the equipment are equally important. This recommendation from the UIAA member federation The British Mountaineering Council (BMC) provides vital equipment information that is NOT explicitly addressed in the standard, particularly failure modes of the equipment and recommendations for the use, inspection, maintenance, and retirement of equipment.