Arc'teryx's new sport climbing harness weighs almost nothing, has only two gear loops, and a waist belt that's just two millimeters thick. Our editor Gwen tested it together with professional athlete Lara Neumeier while sport climbing in Switzerland.
Les Eaux Noires is a small but exquisite sport climbing gem in the Lower Valais region, near the Swiss border with France. The 40-minute approach is short, but well worth the effort, as is the fantastic climbing itself. You follow a small path, cross a river, and then continue along the riverbed. The rock is gneiss: grippy, textured – in short, simply superb climbing. The area boasts a variety of sport climbing routes ranging from about 6a+ to 8b, so there's something for almost everyone, even if you're accompanied by a professional climber.
Various routes, different difficulty levels, perfect conditions – because the nearby riverbed pleasantly cools the climbing area. Also included: Lara Neumeierthat the Lithos SL who has been climbing for a while, and me, who was wearing it for the first time.
Initially, less than expected.
The Lithos SL is very thin. The waist belt is only two millimeters thick, the leg loops are narrower than I'm used to, and the transition from the tie-in loop to the leg loops is also slimmer than on other harnesses. It doesn't feel fragile, but it still takes some getting used to when you first hold it. Fresh out of the packaging, it feels stiff at first. But Lara can put those concerns to rest immediately: she's been climbing with the harness for a while and describes how it molds itself nicely to the body over time. What I experienced as "still a bit stiff" one day is apparently just a phase that passes. And after several weeks of sport climbing with the Lithos, I can now fully endorse this statement (a typical break-in period, we all know that from our shoes, right?).
The same applies to the gear loops: they're significantly stiffer than I'm used to, being dimensionally stable rather than soft. Unusual, but actually quite cool when climbing. The reinforced plastic loops sit on small spacers that keep them a bit away from the waist belt. This prevents the loop from collapsing.
Warp Strength Technology: Why two millimeters are enough
Warp Strength Technology (WST) is an Arc'teryx innovation with a long history. The manufacturer first introduced WST in 2008 and has refined it several times since – implementing it in big-wall, sport, and trad harnesses in 2011, and revising it in 2015 and 2020. Today, the technology is incorporated into virtually their entire harness range. The Lithos SL utilizes the latest generation. A classic climbing harness consists of a load-bearing webbing encased in padding. The webbing carries the load, and the padding prevents it from digging in. The load is concentrated on the narrow webbing, and the padding must be correspondingly thick to absorb it. This is why comfortable harnesses are usually thick.
Warp Strength reverses the system. Instead of a narrow band in the padding, Arc'teryx uses wide, multi-layered webbing structures that distribute the load across the entire width of the waist belt, rather than concentrating it in a single strip. When the load-bearing material itself spans the full width, there's no need for thick padding to distribute the pressure. For the Lithos, this means less material with the same load distribution.
Images above: Details of the new Arcteryx climbing harness: The new system for adjusting the elastic straps that connect the waist belt and leg loops, the gear loops, and the harness tightened during a high step. Below: Even prolonged hanging in the harness is not uncomfortable in the Lithos, as it distributes the load very well. | Images: Lacrux.com
In practice, this means: the waist belt didn't dig in. We did a lot of bouldering and projecting, and consequently spent a lot of time hanging in the harness without it ever becoming truly uncomfortable. Conclusion: Warp Strength works. The load is distributed really well.
A brand new unisex sizing system for the perfect fit
The Lithos SL comes in Six waist sizes, each with two leg loop optionsSize A has a smaller circumference and standard rise, while size B has a larger circumference and longer rise. That makes twelve sizes. The system is unisex – Arc'teryx is replacing the classic men's/women's division to ensure that the harness isn't simply chosen based on gender, but is truly tailored to the individual's body shape. For example, someone with a narrow waist and more muscular thighs often had to compromise, especially with harnesses that didn't have adjustable leg loops. This new sizing system eliminates that problem.
On the rock: The Lithos SL is a lightweight
The Lithos SL is barely noticeable. Compared to other climbing harnesses, it weighs practically nothing. Arc'teryx claims 275 grams. You hardly even realize you're wearing it. I didn't feel restricted in the slightest. A two-millimeter waist belt and narrow leg loops have almost no bulk that could get in the way when edging or spreading your legs. The material is also flexible and follows your movements instead of forcing a shape upon them, and the tapered, seamless leg loops don't dig in with a hard edge when you bend your knees. The single pull on the waist belt is incredibly quick and easy to use.
It's totally unusual to only have two gear loops. But in my opinion, you don't need more for sport climbing.
Small, lightweight, well-designed
One point that might seem almost secondary with such a lightweight strap is its pack size. The Lithos SL folds down extremely small. It comes with a small stuff sack that seems almost too high-quality for its purpose, but the strap slides in and out without any stuffing or fiddling. This is definitely a plus for anyone who travels a lot. The material of both the strap and the sack is also water-repellent.
The buckle also deserves a mention. The belt is closed with a single pull, and the forged buckle does what it's supposed to: once adjusted, the belt stayed in place all day without me having to readjust it or tighten anything.
And then there are the elastic bands that connect the leg loops to the hip belt at the back – they can be unhooked with one hand, even with the belt tightened. It's a little stiff at first, but it's not supposed to come undone on its own.
For whom – and for whom not
The Lithos SL is a sport climbing harness. I wouldn't use it for multi-pitch or alpine routes – you need more gear than you can carry on two loops. But Arc'teryx isn't targeting those areas with this new harness. If you're looking for a do-it-all harness, this isn't it. But if you're looking for a sport climbing harness that's lightweight, fits snugly, and offers good flexibility, then this is exactly what you need.
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