The Arc'teryx Beta SL is an impressive shell pant for a variety of uses. They are lightweight enough for backpacking and durable enough for moderate mountaineering adventures. The feature set reinforces this versatility as well, with full-length side zippers that allow you to don them without removing whatever is on your feet, like skis, crampons, or muck boots. The Beta SL pants are darn close to being the dream "quiver-of-one" shell pant. The monetary cost is high, but if you appreciate durability, versatility, and lightweight, these are an excellent value.
Arc'teryx Beta SL Pant - Women's Review
Compare prices at 3 resellers Pros: Full length side zippers, durable, versatile
Cons: Expensive, awkward without front fly closure
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Our Analysis and Test Results
The Beta SL shell pants are an incredible blend of versatility, durability, and light weight.
The Beta SL pants are made with Gore-Tex Paclite Plus fabric, which is one of our favorites for a variety of reasons. For this metric, we found it to perform with excellent reliability. The material is robust and durably waterproof. Admittedly, most waterproof fabrics do the waterproof thing pretty well; it's more challenging to nail the breathability component or to make plastic clothing comfortable for athletic pursuits. As such, the other way waterproof pants can fail is where any holes may appear. Any pocket or zipper is functionally a hole in the pants, which must be reinforced in some way. We like the waterproof zippers on Arc'teryx products, and find that they seal water out well while being easy to operate; waterproof zippers can be sticky and gummy to operate, which often makes them wear out sooner as well.
The stiffer material keeps the fabric tented over your skin, whereas more supple fabrics can stick to your skin more easily. This is not necessarily a waterproofness issue, but it certainly affects our perception of how dry we fell when wearing the pants. It actually has to do with the material clinging to (or close to) your skin and inhibiting wicking and ventilation of any internal moisture.
Comfort and Mobility
The only complaint we have in the comfort/mobility metric is that the lack of a fly closure makes these pants a little finicky to put on. The closure system is at either side of your hips instead of in front, which is less intuitive. When wearing bulky, warm clothing, it can be more challenging. That said, the utility of having full-length side zippers in such a lightweight hardshell pant is phenomenal. This feature makes it reasonable to use these as an ultralight shell pant for skiing and mountaineering, where it is critical to be able to get an emergency storm shell on in a hurry when you can't necessarily put your feet through pant legs.
The lack of a front fly, combined a with rigid front waist paneling (only the back half of the waistline is elasticized), also makes these pants articulate differently. However, the intelligent paneling design and gusseted crotch, a mastery of design function typical of Arc'teryx shell products, still makes these pants move remarkably well for plastic clothing.
Breathability and Venting
The Paclite Plus Gore-Tex material is among the more impressively breathable shell designs, especially for the combination of reliability and ruggedness with lightweight. These are 2 layer shell pants we would take on bigger alpine objectives where light weight is key, but you definitely still can skimp on performance and take a flimsy (but even lighter) rain shell pant. The Paclite Plus material features the Gore-Tex membrane laminated on a durable, abrasion-resistant shell, which is then treated on the inside to be more durable without needing another layer or half layer (which would make these a 2.5 of 3 layer pant instead). This makes for excellent waterproofness with impressive breathability and light weight. Wow. All the things.
As such, these pants fill a performance niche angled more toward the fast-and-light. Appropriately, the Beta SL can also ventilate in a hurry, in two directions. You can keep the hook-and-loop closure intact at the waist and unzip the side zippers from the top; and there is another zipper at the bottom of the leg, with a button closure around the ankle, so you can ventilate from the bottom hem as well without freeing the leg material to flap around.
The Beta SL pants have more features, long zippers, and extra durable fabric where it matters most.
All of this adds up to a bit more weight. However, we still scored them above average for weight because when you consider the versatility afforded by the features, the weight is remarkably low. High versatility, low weight, great product.
When we roll up the Beta SL pants, they are smaller than a 1-liter water bottle, and are impressively compact shell pants for their relative performance. For our mountain guide testers, we feel quite content with two pairs of shell pants in our quiver with the advent of the Beta SL. We have an incredibly rugged 3L shell pant for expeditions and severe weather with a high level of commitment (i.e., if you don't have the best shell you might get into a dangerous situation), but for most conditions, the Beta SL is appropriate.
The standout feature on the Beta SL pants is the full-length side zippers. For the testers who are mountain guides, this was a dream come true.
These full-length zippers allow you to don the pants when wearing crampons or skis because you don't have to put your foot through the legs to put them on. Additionally, you can wrangle the pants on under a harness, or take them off when wearing one, which is very freeing. The pitfall of this design is in the waist closure system. The hook and loop can be finicky, sometimes coming unhooked, and it is difficult to maneuver with gloves on.
The design of the pants is consistent with this usage as well, with a more durable material on the inner ankle where you are most likely to catch a crampon or scuff your ski boot cuffs together. As mentioned in the mobility metric, the lack of a front fly does affect the mobility of the pants, and makes them a bit more difficult to put on. However, when compared to having to take off your crampons, this is a manageable inconvenience.
Arc'teryx nailed the balance between light weight and durability with these shell pants.
They have lightweight 40 denier fabric throughout the pants, with much more burly 150 denier fabric at the hems and instep to resist abrasion from boots or crampons. The waterproof zippers are smooth and easy to operate, which inspires confidence in their long term durability as well. Many waterproof zippers we have experienced feel sticky and gummy, and wear out sooner.
By definition, the Beta SL pants are an incredible value. They're expensive, objectively, but for our testers who guide mountains all over the world, these come the closest to answering all of their prayers for a highly versatile, durable, and lightweight shell pant. These are not the most rugged for expeditions or serious alpine missions, but they allow you to push the limits of what we have come to expect from lightweight shell pants (which, admittedly, we carry around in our packs a lot more than we actually wear them).
The Arc'teryx Beta SL pants are one of our all-time favorite shell pants. These pants come the closest to being a quiver-of-one shell pant for our avid mountaineers. They are versatile, durable, and remarkably lightweight. This comes at a relative high monetary price, but our experience with Arc'teryx products tells us that if we care for their garment well, they can last for years.
— Lyra Pierotti