The world's most in-depth and scientific reviews of outdoor gear

Arc'teryx Alpha SL Pant Review

Rugged, weather proof pants constructed with important accents and a minimum of extra; the fabric is among the most breathable available.
Editors' Choice Award
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Price:  $270 List | $269.00 at Backcountry
Compare prices at 3 resellers
Pros:  Rugged and dry, breathable fabric, excellent weather protection, excellent fit promotes range of mobility
Cons:  Expensive, no pockets, scratchy and loud fabric
Manufacturer:   Arc'teryx
By Jediah Porter ⋅ Review Editor  ⋅  Nov 9, 2018
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91
OVERALL
SCORE


RANKED
#1 of 10
  • Water Resistance - 25% 10
  • Comfort and Mobility - 18% 9
  • Breathability & Venting - 18% 10
  • Features - 5% 8
  • Packed Size - 12% 8
  • Weight - 17% 8
  • Durability - 5% 10

The Skinny

These are the best rain pants in our review and are highly recommended. As long as the cost is in your budget, you cannot go wrong with these pants. The weather protection and breathability are both unmatched elsewhere in our review. Some pants are more comfortable, especially if the loud texture of the Alpha fabric really bothers you. Some of our testers didn't like the noise and sensation of the fabric Arc'teryx makes these from. The stretchy and quieter fabric of the other Editors Choice Mountain Hardwear Stretch Ozonic makes for a more comfortable and lighter option, with poorer weather protection.


Compare to Similar Products

Our Analysis and Test Results

Rain pants: a product for keeping the rain off your legs. And so much more. We rely on our "rain pants" to also protect against wet brush, wind, falling snow, sleet, cold, walking and skiing through deep snow, and so much more. We ask all of these tasks from a product that may live in our backpacks for 99% of its life. When we need rain pants, we really need them to work well, but we want them to be compact and unobtrusive when packed. For all these reasons -for this delicate balance- we choose the Arc'teryx Alpha SL as our Editors' Choice. It is a top of the line product that is light weight. There are beefier shell pants out there (check out our upcoming addition of the Arc'teryx Beta AR, for instance) and there are lighter options (check out many of our other award winners) but none strike the balance that these do. The one that comes close is the other Editors Choice Mountain Hardwear Stretch Ozonic. The Ozonic is an excellent pair of pants also. They are lighter and a little less durable. The are more comfortable but a little less protective. The balance is still strong, and either one is a worthy choice.

Performance Comparison


These top our charts, both in a subjective "which one is best?" kind of way and when we crunch the numbers and generate our proven weighted score.

It is in duress that the full zip attribute of a pair of shell pants becomes truly valuable. Here  lead test editor Jed Porter on a Chile's Volcan Lonquimay in tough weather  preparing for a white-out ski descent.
It is in duress that the full zip attribute of a pair of shell pants becomes truly valuable. Here, lead test editor Jed Porter on a Chile's Volcan Lonquimay in tough weather, preparing for a white-out ski descent.

Water Resistance


Water simply won't get through these pants. It might sneak in from the top or from the bottom, or through opened zippers, but it won't get through the fabric. Wear them carefully and whatever is beneath won't be contaminated by external water. Arc'teryx and Gore have worked together for years, and all their products do well in our tests for weather resistance. The Alpha SL pants, in our extensive and very wet testing, showed no breach. In any given rainstorm, eventually, the DWR of any shell gear will fail. As time goes by, this failure will come earlier and earlier in each wet event. The Alpha SL DWR works as well as any, and a little better than most.


With all the rain pants we tested using waterproof breathable laminates, it is mainly in construction and DWR that they differ. The waistband and cuff integrity are primary, among the construction variables. The belted waist and elastic cuffs work together to keep out the weather on the Alpha SL. Further, there is a lace hook on the cuffs of the Alpha that holds the pant legs down over your shoes. The result is a weather protection system that exceeds that of all the other pants we tested. Only the Marmot Minimalist matches the water resistance of this Editors Choice winner.

We hope that the dedication of our testing staff comes through in this photograph. We spent hours in this particular South American storm testing rain pants. It is due to this rigor that we can confidently grant the Editors Choice award to the Alpha SL.
We hope that the dedication of our testing staff comes through in this photograph. We spent hours in this particular South American storm testing rain pants. It is due to this rigor that we can confidently grant the Editors Choice award to the Alpha SL.

Comfort and Mobility


These fit like a glove and are contoured for range of motion. Big steps and flexible moves are no problem. Our only complaint is the somewhat "loud" fabric. Especially when brand new, the fabric brushing against itself makes a lot of noise and creates a "feel" that many testers didn't dig. The fabric "breaks in" with time, but always remains a little crinkly.


The softer and lighter fabrics of the Marmot PreCip pants (both regular and full zip) and the stretchy and quiet construction of the other Editors Choice Mountain Hardwear Stretch Ozonic are marginally more comfortable, in those specific attributes than the Arc'teryx. Overall, though, the tailoring of the Arc'teryx makes up for some of its shortcomings.

Close up of the waist band closure of the Alpha SL. This metal here  on any full zip pants  is inevitable. It will bind under your pack waist belt  but that can't really be avoided with full zip pants.
Close up of the waist band closure of the Alpha SL. This metal here, on any full zip pants, is inevitable. It will bind under your pack waist belt, but that can't really be avoided with full zip pants.

Breathability and Venting


Of the waterproof, breathable fabrics we have tested, GoreTex iterations definitely breathe among the best. Now, realize that, in super wet conditions where you are working hard, sweat will collect on the inside of the fabric. There is no way to avoid that, especially when the air temperatures are colder. This is simple physics. This is the same reason that even your most breathable of cotton t-shirts collect moisture: evaporation can only happen so fast, and your body produces it faster than it can go away. Shell gear of any sort slows that down, no matter how "breathable" we might claim it to be. When we compare breathability of waterproof gear, we are making relative comparisons. That being said, the Alpha SL is indeed quite breathable. You will appreciate it, especially if you have used less breathable products.


Only the products also made with Gore-Tex fabric (Marmot Minimalist) and the Mountain Hardwear Ozonic match or exceed the Alpha SL in breathability. All the others use proprietary membranes that simply do not breathe as well. Of those, the "NanoPro" coating on the Marmot PreCip products is the most breathable.

The Alpha SL rain pants breathe well enough to shed a moderate amount of interior perspiration while working on most terrain. Heavier perspiration will overwhelm the breathability of basically any clothing.
The Alpha SL rain pants breathe well enough to shed a moderate amount of interior perspiration while working on most terrain. Heavier perspiration will overwhelm the breathability of basically any clothing.

Features


These pants have no pockets at all. The most salient features (that do not fall under venting or the other scoring criteria) are the fully separating side zips and the zipped fly. Both of these are convenient and make the pants that much more usable. Both add a small amount of weight and bulk, but most of our testers deem them worthwhile. In fact, most of our test team wishes that there was a pair of front pockets on these pants for convenience. It wouldn't have to add more than an ounce or two, and would really round out the feature set.


Many of the other pants we tested have more features than the Arc'teryx Alpha. Only the Best Buy Columbia Rebel Roamer also has zero pockets. All the others have at least one pocket. The Marmot PreCip Full Zip has three pockets and the REI Talusphere Full Zip has two. The other Editors' Choice Mountain Hardwear Stretch Ozonic has just one pocket.

The fly  waist band  and side waist buckles of the Alpha SL.
The fly, waist band, and side waist buckles of the Alpha SL.

Packed Size


For the weather protection and durability, these pants pack down pretty small. The fabric feels substantial and stiff, but the final package is almost as small as some of the lighter feeling pants. They take up about as much space as a 12 ounce can of coke.


The Top Pick Outdoor Research Helium is the packability leader, taking about half the space of the Alpha SL, while the Marmot PreCip is about 75% the size.

Packed size of the Editors' Choice Alpha SL from Arc'teryx.
Packed size of the Editors' Choice Alpha SL from Arc'teryx.

Weight


These pants weigh thirteen ounces or 370 grams. Like we've been saying, that's pretty good given the other performance attributes. There are lighter pants, but none perform as well as these in rugged weather.


The lightest pants we tested are exactly half the weight of the Alpha SL. The Top Pick Outdoor Research Helium weighs 6.5 ounces. At the other end of the spectrum, the REI Talusphere Full Zip weighs 6.6 ounces more than the Alpha SL. Essentially, the Alpha SL is exactly in the middle of our tested range but is a little above the mean weight value.

We like the lace hook on the Alpha pants. This holds the pants down over your boot cuffs for an even better seal against the elements.
We like the lace hook on the Alpha pants. This holds the pants down over your boot cuffs for an even better seal against the elements.

Durability


This is really where these pants shine. Aside from the degradation of the DWR (which is inevitable, and can be replenished), these pants should hold up for hundreds of hours of use. Unless you cut them on crampons or ski edges or rugged brush, you might not even notice any wear after years of routine use. Now, of course, "routine use" shouldn't include daily wear. Daily rain gear use doesn't sound like any sort of fun.


Only the much heavier products begin to approximate the durability of the Alpha SL. The rugged construction of the REI Talusphere Full Zip will last longer than the Alpha. The North Face Venture Half-Zip is pretty rugged, but will likely suffer failure sooner than the Arc'teryx.

Two pairs of rain pants  for comparison. On the right is a pair of Alpha SL pants that has been worn extensively. The collected and visible wetness is the result of failed DWR. That can be replenished and will not get through to the inside of the pants.
Two pairs of rain pants, for comparison. On the right is a pair of Alpha SL pants that has been worn extensively. The collected and visible wetness is the result of failed DWR. That can be replenished and will not get through to the inside of the pants.

Best Applications


These are great all-around shell pants. Wet weather hikers will dig 'em, and alpine climbers will use them in the most rugged of retreat conditions. For certain backcountry ski applications, they will be handy. One tester wore them for wet commutes on his motorcycle.

Shell gear testing gets good when its raining hard enough that photography gets hard. Here  foggy and wicked wet conditions near snow line in Patagonia  testing the Alpha SL for your benefit.
Shell gear testing gets good when its raining hard enough that photography gets hard. Here, foggy and wicked wet conditions near snow line in Patagonia, testing the Alpha SL for your benefit.

Value


Like all Arc'teryx gear, these are not inexpensive pants. However, the durability can make them a better value. If you look at "dollars per use", the cost of the Alpha SL makes more sense.

Interior of the zipped open cuff of the Alpha. You can see interior reinforcements  drawstring cinch  lace hook  and grommets for application of your own elastic instep stirrup.
Interior of the zipped open cuff of the Alpha. You can see interior reinforcements, drawstring cinch, lace hook, and grommets for application of your own elastic instep stirrup.

Conclusion


Aside from the "loud" fabric, these are perfect all around shell pants.


Jediah Porter