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Carabiner Design, Evolution, & The FS Mini

I was browsing the local gear shop yesterday when I stumbled upon the Metolius FS Mini carabiner for the first time. It is shockingly small, so small in fact, that I think it has lost much of the functionality of a traditional carabiner.

fs mini clipping from Climbing House on Vimeo.

This realization led to a review of the existing lightweight ‘biners, and the
design discussion that follows.

Lightweight Carabiner Review

Left to Right: BD oval (for reference), Mammut Moses, BD Oz, CAMP Nano, Metolius FS Mini

I compared existing wire gate carabiners based on price and weight (quantitatively) and size (qualitatively). I did not include any ‘biners with special features (such as a “clean” nose) in order to hold constant as many variables as possible.

The graph above shows the general relationship between ‘biner cost and weight. Lighter ‘biners are typically more expensive. The most interesting points on this figure are the ‘biners that deviate further from the best-fit line.

It is shown that:
1. The Metolius FS Mini, Omega Dash & CAMP Orbit are more affordable than would be expected.
2. The DMM Phantom is particularly expensive. This is probably due to the cost of import, and their general design & production.

Regarding size: I feel like the FS mini is too small for me to comfortably use. The BD Oz is even a little small, as my finger still gets stuck in it when clipping. That said, I own a bunch of BD Oz carabiners, and overall I’ve been pleased.

Design Discussion
So objects evolve through time. In carabiners, there are two distinct evolutionary paths: improved performance and reduced weight. BTW these paths are not mutually exclusive.

Improved Performance

Refer to the image above for some of the many performance improvements introduced to carabiner design.

Reduced Weight

There are a bunch of design concepts that can be implemented to reduce weight. Designer have mainly used shape factor (overall shape and cross section), material, and size.

So there are some problems:
1. To reduce the weight of the object, the size is reduced. As size is reduced, usability is also reduced.
2. As weight is reduced, strength is also reduced.

The wonderful thing is these problems have been solved before, many times, in other industries. In The Innovation Algorithm, the author lays out principles that have historically worked to solve basic contradictions. Based on his easy to use tables, I propose a number of possible solutions to the FS Mini problem.


1. Change Materials. Peter Metcalf of Black Diamond said that he expects plastic carabiners in the future.

2. Reduce usable lifetime. Probably related to #1. Provide less durable carabiners for very specific (not everyday) uses.

3. Change the gate design. The main functional problem with the smaller carabiner is that my finger gets stuck in it. Omega Pacific uses a gate swing that is offset from the spine of the carabiner. This increases the biner opening width. This design, or a similar design such as the gate opening 90 degrees from the spine or out instead of in would solve the functional problem.

4. Design a gate that stays in two positions- open or closed. This would stop the gate from “grabbing” the users finger while clipping.

This close up of the Black Diamond Oz carabiner illustrates using the shape factor to reduce weight.

Climbing equipment has evolved over time, and it will continue to evolve. I hope to see some of these suggestions implemented in future models of lightweight carabiners.

Some related articles that might interest you:
1. SuperTopo review of the FS Mini
2. article on carabiner production
3. general discussion on the FS Mini

Mary Ann - Hi Eli,

I really enjoyed this analysis–and learned a lot!January 23, 2010 – 8:44 am

Steve - Nice work, Eli. Isn't it odd that the cost is less even though the heavier 'biner uses more material? I guess that is explained by the production and design costs of the smaller units, and possibly by the content of the materials used. Other than being lighter, do the lighter 'biners have a similar performace character, e.g. strength to weight?

Steve from OmahaJanuary 23, 2010 – 9:41 am

kris - Interesting insight, Eli. I particularly like the cost/weight plot – it's amazing how much information it displays so simply.

At first, I whisked over your 3rd solution, but got to thinking about it later. It's that kind of out-of-the-box thinking that breeds potential. Coincidently, I was looking at the new issue of Climbing Mag today and saw an eerily similar take on that solution. Not sure how I feel about it, but take a look at it here. (Photo credit: justthemaid)January 23, 2010 – 6:01 pm

Eli - Kris- Funny, I also just saw that add in Climbing. FYI, I hadn't seen it when I wrote the article. I think that solution is more similar to "4. Design a gate that stays in two positions." I look forward to seeing one of those in person.January 24, 2010 – 10:41 am

kris - I guess I was referring to "4" the whole time in my comment instead of "3", because I just noticed your numbering goes "1,2,2,3". He he.

Anyhow, I'd like to see one too. One disadvantage to them may be snagging on each other when racked on your harness (if they are in the open position). In light of that, they may be more fit for sport climbing – otherwise they could snag on even more gear.January 24, 2010 – 10:59 am

Eli - Numbering fixed.January 24, 2010 – 11:33 am

Adam - Good analysis, Eli.

I think the ultra small carabiners are probably great to have for long, easier routes with miles long approaches. Any weight reduction is welcomed in those situations. However, in the type of climbing we're more likely to do, easy, timely clipping is important and at times make or break. If the gate doesn't open wide enough to slot the rope without a struggle, the loss of functionality is too big a drawback.January 24, 2010 – 11:47 pm

Bob - Dude your thumb is huge. it’s not the euipment it’s YOU. You got ogre thumbs.December 20, 2010 – 11:57 am

Matt - Any chance of refreshing the photos from your Picasa page, or re-sourcing them? None are showing up. Thanks!December 21, 2011 – 10:54 am

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