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Osprey Atmos 50 Backpack REVIEW

A durable and effective load carrier with an innovative back panel that keeps your back cool.


by Ken Knight | 2005-05-10 03:00:00-06


Osprey Atmos 50 Backpack - 1
The Osprey Atmos 50 worn by the author. Because so much of this pack's volume is divided among the various pockets, bulky items, like your tent and sleeping pad, can be difficult to fit inside the backpack.

The Osprey Atmos 50 is the largest backpack in the Atmos series with a volume of 3,050 cubic inches (50 liters). Its solid construction, 11 compartments, innovative Airspeed suspension, and two hydration ports are all packaged in a 2 pound 13 ounce (1.28 kg) production backpack. While the Atmos 50 is hardly the lightest backpack in its size class, you will be hard pressed to find a comparable backpack, with similar features, weighing less. The Airspeed suspension sets this backpack apart from the rest with its trampoline-like mesh back panel that is given tension by a flexible hourglass frame. The frame is stiff enough along the vertical axis to support the pack load and flexible enough to easily twist with your hips and torso as you move. The tubular and rod aluminum, spring-loaded frame suspends the main backpack compartment 1.5 to 3 inches from your back. This creates an open, zipper accessible, space that is not only an excellent place to store a water bladder, but makes the Atmos 50 exceptionally breathable.

Our pre-production sample had a comfortable carrying capacity of 25 pounds. As the load was increased, the lower edge of the hipbelt started to dig into our hips. The Atmos 50 can definitely handle loads heavier than 25 pounds (one reviewer started a desert backpacking trip with 42 pounds), but when loads exceed 30 pounds we all felt discomfort from the hipbelt.

In Brief

  • Bombproof by lightweight backpack standards.
  • The Airspeed suspension creates a superbly breathable and comfortable backpack with a frame that is stiff enough to support even large loads, but flexible enough to easily conform to the user's movements.
  • Eight external pockets, two hydration pockets, and the main packbag make compartment style packing a breeze.
  • The back panel hydration pocket is easily accessible and does not use precious space in the main packbag.
  • The two hipbelt pockets are great for storing small "essentials" and reduce the need to take the pack off to retrieve such items while on the trail.
  • The hipbelt angle limits the carrying capacity, conservatively, to 25 pounds - far less than the carrying capacity of the Airspeed frame.
  • Heavier than many internal frame backpacks of similar volume.


• Backpack Style

Internal frame, panel loading

• Fabric Description

Our pre-production review samples were constructed of 410d broken twill weave nylon (red) and 210d double ripstop nylon (gray). In production packs, Osprey has replaced the 410d nylon with a lighter 210d broken twill. A durable stretch material (also gray), similar to but lighter than Spandura, is used for the pockets.

• Sizes Size M tested

SizeTorso Length (in)Torso Length (cm)

• Weight

3 lbs 1.1 oz (1.39 kg) as measured, size medium. Our pre-production samples were constructed with heavier fabrics than intended for final production packs. According to Osprey, the production Atmos 50 packs weigh 2 lbs 13 oz (1.28 kg).

• Volume to Weight Ratio

67 ci/oz size M (Based on 3,050 ci and Osprey provided weight of 2 lbs 13 oz)

• Load Carrying Capacity

25 lbs, determined by Backpacking Light. Manufacturer's rating not provided.

• Carry Load to Pack Weight Performance Ratio

9 (based on 25 lbs and Osprey provided weight of 2 lbs 13 oz)

• Model Year




Frame, Suspension, and Pack Load Carrying Performance

Osprey Atmos 50 Backpack - 2
The Airspeed suspension used by the Atmos series packs combines a mesh trampoline-like back panel with an aluminum hourglass shaped frame to suspend the main packbag away from your back.

The Osprey Atmos series backpacks are set apart by their lightweight Airspeed suspension. Built of tubular and rod aluminum, the Airspeed frame turns the mesh back panel into a stiff, trampoline-like, surface and suspends the backpack several inches away from the wearer's back. This keeps your back extremely cool and comfortable. A centrally located pivot allows the upper and lower portions to twist independently. This, combined with the flexibility of the mesh back panel, allows the backpack to conform and move with the individual's body shape quite effectively while still providing enough rigidity to carry heavy loads.

I used the Atmos 50 on backpacking trips along the notoriously hilly northern Virginia section of the Appalachian Trail called the Roller Coaster, as well as several hikes in Michigan. The backpack was also tested on a desert hike where carrying large amounts of water was essential. We found that the hipbelt was the primary limiting feature to carrying heavier loads. As loads increased past 25 pounds, the lower edge of the hipbelt would begin to cut into our hips. The hipbelt does a poor job of spreading the weight evenly. The frame is certainly capable of carrying loads far heavier than 25 pounds, but we found that carrying large loads for extended periods of time was quite uncomfortable. The shoulder strap padding is light and thin, and while the straps conform to most body types, one reviewer experienced discomfort just below and to the inside of the armpit.

Usable Features and Ease of Use

Osprey Atmos 50 Backpack - 3
The space created by the Airspeed suspension and back panel is ideal for storing water bladders (two 1-liter Nalgene flexible canteens and a 2-liter Platypus bladder) without sacrificing precious main compartment volume.

If you prefer to separate gear into many pockets, instead of in one great maw, the Atmos 50 probably has a pocket to suit your needs. There are a total of 11 compartments in this backpack: eight exterior pockets, the back panel hydration pocket, the internal hydration pocket, and the main packbag.

The back panel pocket provides an easy way to carry hydration bladders. This pocket is accessed through an inside zipper at the top of the main packbag and is large enough to easily hold 4 liters of water. This is the best place to store water: you do not sacrifice precious space in the other pockets nor have to unpack the backpack to access the water bladders. Some reviewers noticed the slight bulk and water temperature of bladders stowed here, but were not irritated by either. If water temperature is a concern, a user could simply wrap the water bladder in thin foam or bubble wrap to insulate it.

There are three other pockets that can carry water. The two side panel pockets are capacious enough to comfortably hold 1-liter bottles. These pockets are not accessible while wearing the backpack, and the compression straps cover them making it hard to remove or insert items without loosening the straps. There is a classic internal hydration bladder pocket built into the main packbag but accessing the bladder in this pocket usually requires unloading the pack and any volume taken up by the bladder reduces internal pack volume accordingly.

The two zippered, mesh pockets on either side of the hipbelt are a clear design winner. You can easily put a small digital camera and notebook in one pocket and use the other pocket to store trail snacks and a pocket-size GPS.

The front, elastic "shove-it" pocket can easily hold a poncho and softshell jacket. While it would be nice if the pocket were a bit larger, it is hardly a major drawback. We found the release buckle to that pocket difficult to actuate, particularly when the pack was full. The female end, which is firmly attached flat against the pack fabric, is the culprit.

Behind the shove-it pocket are two vertical pockets accessed through water-resistant zippers and backed by urethane-coated fabric. Since these share pack volume with the main packbag, filling the main compartment with gear reduces what these pockets can hold and limits their usefulness.

The top lid pocket is spacious. I found I could generally reach up to open and close the pocket to retrieve strategically placed items without removing the pack. The floating design also allowed stowage of a rain jacket or similarly sized item under the hood.

The Osprey Atmos 50 has four compression straps: two on each side panel. These were effective at compressing and controlling the load. The lower two unfortunately cover the two vertical side pockets making these difficult to access while wearing the pack.

There are two ice axe loops at the bottom of the pack with corresponding loops on the upper sides to attach long pieces of gear such as tent or trekking poles. On the bottom, front panel of the Osprey Atmos 50 are two webbing strap loops, adjustable with small side release buckles, that are sized right for a small four-season tent in its stuff sack or a foam sleeping pad.


As mentioned previously, our review sample was a pre-production prototype. There will be changes in the production model, notably a switch to lighter fabrics. During my tests of the backpack I saw no signs of unexpected wear. The fabrics in the pre-production model were virtually bombproof by lightweight backpack standards. Osprey's decision to lighten the fabrics is appropriate.


The Osprey Atmos 50 a good value. It's replete with features, has a design that provides superior ventilation, and a frame that readily conforms to your body, and it's well built. For those who prefer simplicity, the myriad of features may act more as a hindrance to packing, and although this pack is a good value for the features, it may not be the best choice for ultralight backpacking.

Recommendations for Improvement

While the Osprey Atmos 50 is a very fine pack there are some things that could be done to make it even better.

The internal hydration pocket is a tight fit for a full bladder. More than once I inadvertently squeezed water out of my bladder while installing it into this pocket. In addition, using this pocket reduces the internal volume of the main compartment considerably. Given the very useful space between the mesh back panel and the main packbag for storing multiple bladders, we would recommend removing the unnecessary internal bladder pocket to reduce weight.

The main limitation to carrying weight in the Osprey Atmos 50 was not the suspension or even the pack's capacity, but the hipbelt. When loads exceeded 25 pounds, our reviewers started to notice the hipbelt digging in. The hipbelt concentrates weight to the lower edge of the belt and results in increasing discomfort with increasing weight carried. Altering the hipbelt angle where it attaches to the back panel, to reduce the pressure on the lower edge, would greatly extend the pack's carrying capacity. With loads greater than about 30 pounds, wearers also started to feel discomfort in the shoulder straps. The shoulder straps hit a bit too wide on the shoulders, rather than draping over the collarbone.


"Osprey Atmos 50 Backpack REVIEW," by Ken Knight. (ISSN 1537-0364)., 2005-05-10 03:00:00-06.