The Arc'teryx Alpha SL is our dream come true; at least when it comes to rain pants. These are a burly yet comfortable pair of shell pants that are light and nimble enough for hiking and backpacking but fully featured and rugged enough for technical alpinism. The Alpha SL has full-length zippers on the outside of both legs, allowing you to put them on over any footwear - from muddy boots to crampons and even skis! They have a subtle crampon patch on the inside ankle of each leg, providing protection from sharp points without adding too much bulk or stiffness to make them awkward for trekking. These rain pants are so much more than a simple rain pant; they also fit the bill for most conditions where you need hard shell pants, and at a fraction of the weight. These pants are an excellent value, useful for anything from long distance treks to light expedition use.
Arc'teryx has dropped the Alpha SL pant from their lineup. The closest replacement is the Zeta SL, which we outline in more detail below.
Our Analysis and Test Results
Zeta SL vs. Alpha SL
Sadly, Arc'teryx has discontinued our favorite rain pant. However, they now make the Zeta SL, which is an even lighter weight shell pant constructed of the same materials. The Zeta, pictured in the first image below (and followed up by the Alpha SL we tested), only has 3/4 length leg zips, while the Alpha featured full zips. Another major difference is that the Alpha didn't have a fly, while the Zeta features a button and zip fly.
We are linking to the Zeta above, but be aware that until we test the new pant, the review to follow is our account of the Alpha SL.
Hands-On Review of the Alpha SL Pant
The Alpha SL shell pants from Arc'teryx are our hardshell pants dream come true. The Alpha SL pants are designed with high-end alpinism in mind, and for that these are brilliant. It is important to note, however, that this focus does not detract from their versatility. The full side zippers make rain pants much easier to get on over wet footwear of any sort, especially footwear that is exceptionally bulky or has sharp things attached to it (like crampons or skis). These pants are so impressively light, packable, and breathable that we think you'll love them on long distant treks and big climbs alike. Should you need something for general hiking, these will also do the trick, excelling at any task you put them up to.
Most waterproof/breathable fabrics used in rain pants do a pretty darn good job of keeping the water out. Many companies use the same fabrics, often from Gore-Tex, and in the water-blocking department, they all do quite well. In this category, therefore, we focus on any design flaws that might make rain pants otherwise leak.
The Alpha SL pants have full side zippers on both sides, which is an undeniable opportunity to let water in. Arc'teryx uses excellent waterproof zippers which hold up well over time, are smooth to operate, and reliably keep water out. These pants score highly for water resistance.
Comfort & Mobility
The Alpha SL pants are the most impressive shell pants we have ever worn. They are light and comfortable enough to wear on longer (and very wet) treks, and articulated so well they allow technical ice climbing moves, even when layered over the top or our already beefy ice climbing pants. We were stunned at how comfortable these pants were in the full range of wet weather activities we used them.
A critical component of mobility is how easy each model is to put on. Since most times we need rain pants it is because we got caught out in weather, we like pants that slide on easily over shoes, boots, and if applicable, skis or crampons. For the latter, you must have full side zips. For this reason, we loved the Alpha SL pants.
The soft interior and slightly stiffer texture of these pants keep the fabric from getting stuck on your clothing underneath, which can be a common problem with more affordable rain pants. Arc'teryx has mastered how to articulate stiffer materials so that these pants move with you nearly as well as the most desirable stretch rain pants.
The only important thing to note here is that the pants have no fly, so you must unzip the side zippers to put the pants on. This means unhooking at least one of the sides, but once you get accustomed to it, it really isn't much different from regular pants with a fly in the front. It took some wrangling when we were wearing big puffy jackets, but overall still worth the effort. This does also mean that the pants have a clean and smooth surface on the front, making it very comfortable to wear under a backpack's hip belt.
The OR Aspire pants have a slightly softer feel, if you prefer a more supple rain pant.
Breathability & Venting
An all-time rating for the Alpha SL pants again! The full-length side zippers allow you to ventilate from either the top or the bottom of the leg, while a button at the cuff and the hook and loop closure at the top ensure the pants stay where you want them - in case you do decide to unzip and shed heat in a hurry.
The Paclite Gore-Tex fabric is also highly breathable - a great combo for helping you manage heat and moisture on the fly. If you don't need so many venting options, you might like the more svelte version of these pants with only cuff zippers, the Arc'teryx Beta SL.
Weight was the weakest evaluation metric for the Alpha SL, but that's certainly not to say it is a weak performer. Compared to other fully-featured, full-zip hardshell pants, these are a fraction of the weight. In this review, the Alpha is the heaviest; however, for an extra few ounces, you get one of the most versatile, durable, useful pairs of rain pants (or rather, hardshell pants, a category of even more burly shell pants) in this review—and arguably across most of the industry.
Until we reviewed these pants, our reviewers were mostly dissatisfied with the selection of pants in this review for the blend of features and bulk/weight. Problem solved! These pants are an ideal blend of useful features, complete with a stunningly small packed size.
Perfect. The Alpha series from Arc'teryx is optimized for alpine climbing, but this does not detract from the versatility of these pants. They have full-length side zippers which make these pants easy to put on or take off, no matter what you have on your feet; this is especially important when you're wearing crampons or skis when the weather rolls in or you wrap around to the exposed side of the mountain. The zipper design also allows you to put these pants on easily over a harness.
The other benefit of the double side zippers is that these pants can be unzipped in a drop-seat fashion if you need to use the restroom. This can be easier than wrestling your pants down, especially if you're wearing a harness.
There is a shoelace hook to keep these pants secured around your boots, a cinching elastic cord at the cuff to seal out the elements, and a crampon patch made of sturdier fabric where you're most likely to kick yourself or snag your pants (inner ankles), but also great for when you're wearing ski boots and you bump your plastic boots together (more fragile fabrics don't do so well in this scenario).
Arc'teryx has an impeccable reputation. They might not be cheap, but this also means their products are definitely not cheap. They use light but durable Gore-Tex fabric with Paclite product technology; in places where more durability is needed, they placed burly N150p-X Gore-Tex fabric.
The design features and every possible weak point in these pants proved to be highly durable, even in the most adverse conditions (like blustery adventures). The zippers are well made and will hold up over time (think years, if well cared for). The crampon patch ensures minimal scuffing and knicking where it's most likely to happen, should you be mountaineering. And the hook and loop closure is so incredibly sturdy and simple that we can't imagine how it would fail.
These are not the cheapest pants in this review. But, as we said before, they are also far from cheap. With Arc'teryx, you get what you pay for. If these pants are well cared for, they will last years. If ice climbing, mountaineering, or winter hiking, the stiffer fabric is easy to patch if you do kick a hole in it with your crampons. But most of all, these pants are light enough to carry on lightweight summer mountain adventures, yet burly enough for those springtime expeditions in Alaska.
We love the Arc'teryx Alpha SL for everything from hiking, to mountaineering, to high-end alpinism - where performance and weight matter most. The Alpha SL pants are easy to get on in any type of weather, on exposed ledges (even easy to put on over a harness), and over whatever we had on our feet—including full-length skis. As technical as these pants are, they are also highly desirable for long, lightweight treks. The technical additions, such as side zips and crampon patches, don't detract from their versatility; and, for how useful these features are, the minimal cost in extra weight is well worth it.
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