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Arc'teryx - Alpha FL 45L Backpack

posted Oct 11, 2014, 7:25 AM by GoOut Project   [ updated Oct 29, 2014, 1:59 PM ]

The Arc'teryx Alpha FL 45L is an ultralight, minimalistic, waterproof backpack designed for 'fast & light' alpine challenges on ice, rock, and mixed terrains. The Alpha FL has the typical clean and minimalistic look that characterises all Arc'teryx products. We had the chance to thoroughly test it throughout a whole season and here we report the results of our tests.

Technical Description

The Alpha FL 45L (FL stands for Fast & Light) is an ultralight, yet very tough and highly weather resistant 33L (expandable to 45L) pack designed for alpine climbing. Everything in the design has been stripped down to the essential: single compartment, no suspension system, no top lid, a single zippered pocket, and no load compression straps. A simple double-pull drawcord, combined with an extendible rolltop collar, compose the closure system. The body is
made of an e
xceptionally light and strong nylon N400-AC2 fabric, coated both on the inside and on the outside to create an air and water impermeable fabric. Minimalistic thermoformed shoulder straps and even reduced width of the seam tape (only 15mm wide) contribute to save every gram. Four attachment points are present (two on each side) to carry skis or a sleeping pad, plus a front bungee attachment to hold crampons or other gear for quick access.

  • One zippered pocket with key clip
  • Reflective white interior
  • Dual haul loops/carry handles
  • Semi-rigid, foamed back panel 
  • Fully seam-sealed
  • Thermoformed shoulder straps
  • RollTop™ closure
  • Extendable collar with drawcord for additional capacity
  • Top compression strap
  • Two ice axe loops
  • Six integrated front lash points
  • Elastic cord front-attachment system for carrying campons or additional items
  • Four integrated side lash points
Pack Body: N400r-AC² nylon 6 ripstop coated on both sides to create an air impermeable, waterproof textile. Taped seams.
Back Panel: HD 80 foam is a high density polyethylene foam.
Collar: N100mr-HT and N70r-HT compose the extendable, water resistant RollTop™ closure.
Shoulder straps: N400r-AC² nylon 6 ripstop, Burly™ Double Weave and Hypercell foam laminated to each other
Waistbelt: 40mm/1.6" wide nylon webbing

Capacity: 33L (expandable to 45L)
Weight: 650 g

Our Test

We tested the Alpha FL 45L for more than 6 months for mountaineering on ice and mixed routes, glacier walking, alpine rock climbing, hiking, skiing, splitboarding, and mountain biking. We used it in a very wide range of temperatures (-5ºC to 20ºC) and in all possible weather conditions, rain, snow, sun, hail, etc.

First Impressions 
Light and robust. These are the first two adjectives that come to your mind when you hold the Alpha FL for the first time in your hands. The design is essential. Basically there is no suspension system. But when you put it on your shoulders, quite surprisingly, it's not so uncomfortable! The thermoformed shoulder straps are well designed and do not bother you even when you carry heavy gear in the pack. The top closure system is very quick and easy to operate even when wearing gloves.

Some of the first comments of our testers:

  • “Light and tough!” 
  • "Very practical on alpine climbs and glacier walking. You can chuck it on the snow without worries."
  • “The same old problem: it's very hard to reach the stuff packed at the bottom.” 
  • “Not very practical for skiing/snowboarding.”
  • "No easy way to compress it, when not full."
Backpacks in the the range of 30-40L weighting less than 1 kg can be generally considered light. With 650 g the Alpha FL is way below the average. It is hard to think of what else you could eliminate on the Alpha FL to reduce weight even further. This pack is already stripped down to the essential and it would be hard to file off more grams without compromising either toughness or comfort, or both.

Design & Functionality
The whole backpack is designed to be extremely simple, quick to use, and very tough. It is very well suited to alpine climbs and glacier walks, when you don't want to carry too much gear with you and you want to move quickly without having to worry about contact with snow and rocks. The ice tool carrying system is very simple, functional, and quick to operate even with a single hand and when wearing gloves. The same is true for the double-pull drawcord closure system. These may seem subtle details, but they come very handy when you have to quickly get out of uncomfortable situations. Another practical feature, especially for big-wall climbing, is the hauling system composed by two loops (or carrying handles), which allow easy hauling or clipping off at a snow anchor or a belay. The four side lash points are not very practical: they are too small, so you can only fit a very skinny sling or an elastic cord through them and if the pack is not full this solution offers only limited support. Despite the white pigmented inner surface, the interior of the pack remains quite dark. Because of its cylindrical shape and the lack of compression straps, the center of balance is always far off the back and this affects quite a lot your balance.

All the unnecessary has been eliminated: no complex suspension systems, no ventilation mesh... and not even compression straps. Despite the lack of fancy back panel design, the backpack is quite comfortable, even when heavily charged. The simple foam panel on the back provides minimal support and structure to the pack and sufficient comfort. The thermoformed shoulder straps are soft and very comfortable and distribute weight very well without creating annoying spots. However, given the lack of a ventilation system on the back the Alpha FL can only really be used in colder temperatures.

The Alpha FL is practically a dry pack! You can sink it in water and it still keeps everything dry inside. What else do you need to protect your gear? Only in the top compartment, in case of heavy rain or snowstorm, water/snow can sometimes penetrate in between the external top opening and the internal RollTop closure.

The nylon used on the body is of really good quality: very tough,
almost indestructible. No matter if you chuck it on the snow, drag it on the rocks, smash it against tree trunks, the outer fabric of the Alpha FL is really hard to die! The straps are also of good quality. The weakest part of the pack is the elastic cord that serves as ice-tool carrying system, which is not destined to a long life. Also the plastic buckles are notoriously the first part of modern packs to get broken. On such a backpack, we would have expected more durable solutions, such as aluminum buckles.

The Alpha FL is a very good pack, but only for some activities, mainly those for which it has been designed. It is practical in all the situations in which you have to be quick on high mountain terrains (on glaciers and mixed rock and ice routes) and for light and fast assaults to the summit. But it has more limitations than advantages in almost all other activities. The top opening is easy and quick to open and close, but the stuff you packed at the bottom cannot be reach unless you empty half of the load. This is an old problem. Packs with
larger, zippered apertures are much more practical. The Alpha FL is also not well suited for high intensity activities in warmer
temperatures. The coated nylon on the back is a sweat trap! 
The the cylindrical shape and the lack of compression straps make the center of balance very far off the back and this make it always unstable. This is something you notice clearly in more dynamical activities, such as skiing/snowboarding and mountain biking.  

Our Verdict 
The Alpha FL has really convinced us for its lightness and toughness, as well as for its quickness and ease of use up in high mountain environments, especially for short and fast climbs/walks on glaciers and mixed ice/snow/rock routes. If used for what it has been designed, that is 'fast & light' style alpine climbing on ice, rock, and mixed terrains, the Alpha FL is a superb backpack. Actually, in our view, the best pack on those kind of terrains and for those activities. For other uses, though, it is quite limited.

+ Very tough
+ Light and simple
+ Totally waterproof


- Not very versatile

- Unstable in more dynamical uses

 Lightness  10/10
 Design & Functionality    8/10
 Comfort    8/10
 Waterproofness  10/10
 Durability    8/10
 Versatility    4/10
 Total Score  8.0/10