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Arc'teryx Alpha FL 40


Arc’teryx Alpha FL 40 Backpack Review

by , January 27, 2021
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Exceptionally durable and weather-resistant pack for rock, ice, or alpine climbing. Alpha Series: Climbing and alpine focused systems. | FL: Fast and light.

That’s the description of the Arc’teryx Alpha FL 40 on their website, which is pretty clear about the concept and the target of this pack. For this reason, you’ll understand my frustration when I received the Alpha right before COVID-19 hit Japan early in 2020. I literally had to wait almost one year before traveling in the Japanese Alps to test the “climbing specialist” Alpha FL in the environment it deserves.

Before putting my hands on this pack for the first time, I was tormented by a conflicting mix of skepticism and an inexplicable desire to own one. I didn’t need this pack. Yet I wanted to be convinced that owning one would be a great idea. Amongst all the packs I’ve owned and debated owning, this is probably the pack that has given me the most mixed feelings. And I’ll be honest. While waiting for future Alps adventures, I’ve started using this mighty 40L for many other purposes such as a climbing gym bag and, most often of all, as a local crag-climbing bag. And I fell in love with it.

Arc’teryx Alpha FL 40

Arc’teryx is a brand that needs no introduction. Their name is synonymous with the fine quality and extreme versatility of gear that has been designed for specific activities with an almost maniacal craftsmanship of details. The brand effort has been rewarded by a proud and robust community of users who support this Canadian outdoor maker with unconditional loyalty and devotion.

As a climber and mountaineer, I’ve been using many different packs over the years, at last finding peace of mind with a specific design typology: the classic removable top lid backpack. More an all-rounder structure that can convert into a lean climbing backpack (like the Arc’teryx Alpha AR 35—which I love—or the HMG Prism). At the same time, I was attracted by the essentialism behind this rucksack, defined by many as the top tier of climbing packs.

This pack, which has been newly improved from the original design, ultimately remains a masterpiece of fast and light alpine climbing and mountaineering.

Arc'teryx Alpha FL 40


  • Name: Alpha FL 40
  • Brand: Arc'teryx
  • Format: Backpack
  • Measurement: Height: 63cm, Width: 30cm, Depth: 25cm
  • Capacity: 40L
  • Weight: 0.715 kg / 25 oz
  • Zippers:
  • Material: N400r-AC² nylon 6 ripstop
  • PriceUS$240


Who It Suits

The Arc’teryx Alpha FL 40 suits alpinists, climbers, and fast and light enthusiasts. This frameless pack found its natural environment in vertical walls. Every feature has been designed around a specific use, possibly for the harshest weather conditions. Still, some people may simply enjoy the look and feel—not to mention, the waterproof construction—of this versatile everyday carry, especially in the 30L size.

Who It Doesn’t

This pack is not for hikers and backpackers because it lacks essential features such as side pockets, side compression, lumbar support, and well-padded shoulder straps.

I assume that many people won’t even understand why this backpack exists. (But I also believe many people won’t get the concept of frameless ultralight packs either.)

Also, mountaineers who have never used lidless packs will definitely have problems with organizing their gear into a single compartment.

Arc’teryx Alpha FL 40



The Arc’teryx Alpha FL models stand for: Alpha – the top tier of technical clothing and gear, FL – fast and light, which leaves no doubts about the application. The Canadian brand designs with performance in mind, so everything on this pack breathes professionalism and minimalism. Probably this is a winning formula for building such great products. Still, they also have an eye for making things look good. Maybe I’m biased, but I really think the streamlined design of this pack looks amazing. I believe a photograph cannot truly convey this. You have to touch one, see how it fits fully loaded on your back to understand how nice it looks. In its red version, it particularly shines…and will certainly be visible in any snowstorm you may meet on your trail.

Arc’teryx Alpha FL 40


The design is a classic single compartment, no-lid pack. Yet it features an innovative approach to create a closure system that works better than the typical alpine roll-top rucksack. The body is streamlined, slightly smaller in the bottom to minimize weight and make it performant when climbing or scrambling.


The pack body features N400r-AC² nylon 6 ripstop which is durable and lightweight. The internal roll-top liner is N70r nylon 6 ripstop.

Arc’teryx Alpha FL 40



The pack has a drawstring closure which is very handy and easy to use with thick gloves. Externally the pack has a small pocket in the front and a drawstring attachment system with ice tool attachment buckles.

Arc’teryx Alpha FL 40

Arc’teryx Alpha FL 40

Shoulder straps have been redesigned in 2020; a simple hip belt strap and a chest strap are minimalistic without frills.

A piece of webbing acts as a rope strap to secure your top loads through a new hook-type of buckle I saw already on the AR series.

Arc’teryx Alpha FL 40

On the side you’ll see compression strap attachments to eventually expand the flexibility of the pack when carrying more gear attached outside the pack, although you need to add your own strings separately.

Arc’teryx Alpha FL 40


Internally the Arc’teryx Alpha FL 40 doesn’t change too much from its predecessor. A small pocket has been added directly on the drybag internal closure.

Arc’teryx Alpha FL 40



This backpack is an updated version of the old Alpha FL 45. Yes, you read that correctly. So why did they shave off 5 liters of capacity? The reality is that the old Alpha FL 45 was a 38-liter pack, extendable to 45L. The extendability of that pack was provided by the full roll-top extension, pulled outside the pack top access, essentially creating a 45L burrito shape. In theory (I didn’t have the old pack to compare) the new FL is, in fact, 40L true capacity without extending the roll-rop. By testing the pack in the mountains, I could fit almost the same gear I usually carry in my HMG Southwest 3400, a 50L pack (+ external pockets). For this reason, I would say the Arc’teryx Alpha FL 40 is, when loaded to the maximum capacity, a 45-48L pack in total.

Arc’teryx Alpha FL 40


Organization is key when packing all your gear into the single compartment of the Alpha FL. Arc’teryx provides two small pockets (one internal and one external) for keeping small stuff like snacks, GPS, or sunglasses handy for quick access. But the rest is up to you and your ability to make your gear sit properly inside the pack. It’s fair to admit that the internal and external pockets become unusable if the Alpha is loaded to the extreme.

I found that by using the internal roll-top liner wisely, it is possible to separate the gear you want to keep dry from the wet hardware you just used on the ice wall. My usual set for a day of ice climbing is a puffy jacket, spare gloves, and food that I stock inside the Alpha’s drybag liner, and then climbing hardware, thermos, and goggles in the open compartment (closed with the drawstring). In this way, you have a two-compartment carry.

Arc’teryx Alpha FL 40


I’ve been reading quite a lot of customer feedback about the old 45L. Almost everybody complained about the shoulder straps being uncomfortable at heavy loads. But it looks like the Arc’teryx product team improved this issue because I think the pack is very comfortable when used with loads under 16-18kg.

Actually, it’s one of the most comfortable packs for short approaches or spring alpinism. However, I’ve also had the chance to carry a decent amount of winter camping and climbing gear, pushing the limits to about 22-24kg, and I definitely missed the straps of my other “workhorse” packs.

Most of the problem happens when the pack is fully loaded and the drybag liner is fully extended. The height of the lid section matches the length of the straps, creating a very delicate balance between the top part and bottom (which makes it very difficult to lift the pack and wear it).

Arc’teryx Alpha FL 40

So, in the end, I would say that this pack is very comfortable until it isn’t. I don’t think Arc’teryx recommends a maximum load but I guess they depend on the user’s common sense to remain under a certain load. The problem starts when an alpinist has the necessity to carry gear for longer approaches—which means full winter camping gear plus climbing gear—but, again, this pack is specifically for fast and light adventures.

Arc’teryx Alpha FL 40

I’ve included accessibility to carry gear under comfort considerations. I have to say the crampons and the ice axes strapped into the front of the pack stay very firmly in place and at the same time are very easy to access and unbuckle, simply by releasing a single drawstring. That’s very important when you are in the middle of a climb and want to put away one ice tool quickly without unloading other gear. 

Arc’teryx Alpha FL 40

Alternatives to Consider

In a similar price range and typology users have many different options. The ones that I would consider as alternatives are:

– HMG Ice Pack

– Exped Whiteout 

– Built To Send X2 

– Mountain Equipment Tupilak 45+ 

– Blue Ice 45

I’d also look into the Alpha AR series (22L, 37L, and 55L) in case you want to stick with Arc’teryx.

Arc’teryx Alpha FL 40

The Good

Comfortable until 16-18kg load, very spacious for its volume, extendable, flexible, ultralight, weatherproof liner. The materials are premium and the build feels very well-made as you would typically expect from Arc’teryx products.

Not So Good

Very minimalistic features, the drawcord in the front feels a bit flimsy after a few uses.

Side compression straps are not provided by Arc’teryx. Whereas other packs like the Mountain Equipment Tupilak 45+ and the Built To Send include those for further customizability. For this premium price, I wish I didn’t have to buy additional straps on my own.

The hip belt is a very thin material. I would have appreciated a slightly more padded version, like the one on the Alpha AR.

The roll-top drybag style could be tedious for someone. The external pocket is barely usable when the pack is loaded to the max. The internal pocket is also tedious to use when the drybag closure is filled to the top.

Arc’teryx Alpha FL 40

Nice To Have

The shoulder straps are comfortable but still not comfortable enough to support the pack fully loaded. I’m sure that improving those wouldn’t have negatively impacted the “fast-and-light” vision of the team.

The ice tool attachments are connected with the drawstring attachment system in the front; I see the cord getting worn out after a few uses. It would be nice to have the same attachment system I have on the Alpha AR series, or at least something separate for the ice tools only.

Arc’teryx Alpha FL 40

I would like Arc’teryx to provide detachable side compression straps when you buy the pack.

Making a roomier external pocket would make a whole lot of difference.

I always wish that backpack makers would offer a detachable top lid to purchase separately (like the Japanese Montbell does). In some situations, like on alpine ascents, you might need different features for different situations: when approaching and making camp, a top lid is very handy to carry stuff you don’t want to leave inside the main pack. When climbing you can just strip the pack to the bones and use it as a minimalistic pack. That is versatility to me.

Arc’teryx Alpha FL 40


The Arc’teryx Alpha FL 40 is a very technical, specialist pack for fast and light types of climbing.

Everybody who owns this pack and uses it in alpine settings will simply love it. And non-believers will simply avoid it. 

As a mountaineer and climber, I recommend this pack for the specific fast and light use. Although with the many available alternatives, it’s up to your budget.

Arc’teryx Alpha FL 40

This article was written by Riccardo Parenti, Italian-born photographer and product designer living in Tokyo. You can check out his work here

The Breakdown

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Geek (Performance)

Space & Access

Style (Design)

Look & Feel
Build, Materials & Hardware

Stoke (Experience)

Warranty & Support
Brand experience
X Factor

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