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Osprey Atmos 25 Backpack REVIEW

Product performance review of the Osprey Atmos 25 small volume, internal frame backpack.


by Jay Ham and Alison Simon | 2005-03-15 03:00:00-07


osprey atmos 25 backpack - field shot
The Osprey Atmos 25 is sized just right for an ultralight weekend as seen here on the California coast

The Osprey Atmos 25 is a small volume, internal frame backpack. At 2 pounds 3 ounces production weight (0.99 kg), it is not the lightest pack in its size class but it has plenty of features and performance to make up for the extra weight. By lightweight standards it's bombproof. Six external pockets and two hydration pockets make packing and then finding gear a simple task. What really sets this pack apart is the Airspeed frame, a trampoline-like, mesh back panel tensioned by a flexible hourglass shaped frame. The frame is stiff enough in the vertical axis to support weight, but has torsional flex to conform to your hips and torso as you move. Osprey combines tubular and rod aluminum to create a spring-loaded frame that suspends the pack away from your back, leaving 1.5 to 3 inches of open space behind the mesh back panel. No more sweaty back. The shoulder straps and hipbelt are perforated as well, making this one of the most breathable packs we've used. The space between the mesh back panel and the main packbag is a great place to store your hydration bladder and saves space in the pack for your gear.

Our pre-production pack has a comfortable carrying limit of about 25 pounds and, with a volume of 1,525 cubic inches, it is difficult to load the pack in excess of that. A slight modification to the hipbelt angle would increase the carrying weight of the pack and prevent the lower edge of the hipbelt from digging in to hips with a 25-pound load.

In Brief

  • Great size and features for an ultralight long weekend backpack trip. Small volume and good compression make for excellent load control and good balance when hiking.
  • The Osprey Airspeed suspension includes a trampoline-like mesh back panel to suspend the pack away from the user's back creating an ultra-breathable, ultra-comfortable experience. The frame is vertically rigid to support the load but flexes with your hips and torso.
  • Six external pockets, two hydration pockets, and the main packbag make compartmental style packing a breeze.
  • The back panel hydration pocket eliminates the need to unpack everything to refill the bladder and does not take up main bag or pocket space.
  • The two hipbelt pockets are particularly functional and greatly reduce the need to remove the pack to retrieve "essentials" while on the trail.
  • The hipbelt angle limits carrying capacity to 25 pounds.
  • A bit heavier than some internal frame packs 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). Osprey has replaced the 410d broken twill 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

Size Torso Length (in) Torso Length (cm)
S <18.5 <47
M 18-21 46-53
L >20 >51

• Volume

1,525 ci (25 L)

• Weight

2 lbs 4.7 oz (1.13 kg) as measured, size medium. Our pre-production samples were constructed with heavier fabrics than intended for final production packs. According to Osprey, the Atmos 25 packs coming off the production line weigh about 2 lbs 3 oz (0.99 kg).

• Volume to Weight Ratio

44 ci/oz size M (based on 1,525 ci and Osprey provided weight of 2 lbs 3 oz)

• Load Carrying Capacity

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

• Carry Load to Pack Weight Performance Ratio

11 (based on 25 lbs and Osprey provided weight of 2 lbs 3 oz)

• Model Year



$139 USD

Frame, Suspension, and Pack Load Carrying Performance

osprey atmos 25 backpack - airspeed suspension
Photo 2: The hourglass shaped Airspeed frame of the Osprey Atmos 25 creates a trampoline-like mesh back panel that keeps you cool and provides space for a hydration bladder. Likewise, the shoulder straps and hipbelt have been perforated with holes to allow these components to breathe. In this photo the hydration bladder is stowed in the hydration pocket inside the pack.

Osprey debuted their new Atmos series packs at the fall 2004 Outdoor Retailers show. The most distinguishing feature of the Atmos packs is the lightweight tensioned back panel Airspeed frame (Photo 2). Constructed of tubular and rod aluminum, the Airspeed frame creates a trampoline-like mesh back panel, suspending the pack 1.5 to 3 inches from your back helping to keep your back cool. The tubular frame is both rigid and flexible at the same time. A pivot located centrally in the Airspeed frame allows the upper and lower sections of the frame to twist independently. The frame combined with the flexibility of the mesh back panel allows the pack to conform to an individual's body shape comfortably. Adventure racers beware - for those with torso lengths on the shorter end of pack size, the top of the frame will likely hit the back of your head while riding a bike.

Osprey continues their design work to keep you cool by perforating both the shoulder straps and hipbelt with 3/16-inch holes. The result is an incredibly airy harness. The shoulder straps also have a sternum strap and load lifters to adjust the fit.

We tested the comfort and carrying capacity in the mountains of northern Arizona and on a coastal California backpacking trip. Overall, we found the frame/harness setup could comfortably carry 25 pounds, limited by the hipbelt. The hipbelt angles downward and concentrates most of the load along the bottom edge causing it to dig into the hips. It would perform better if the hipbelt were at an angle that spread the load equally from the top to the bottom of the belt. Best results are achieved if the pack rides higher than typical so that the hipbelt is high on the hips. The shoulder strap padding in the Atmos series is thin and light and conforms well to match body shape. With a volume of 1,525 cubic inches, it is difficult to load this pack in excess of its carrying capacity.

Usable Features and Ease of Use

Although not the lightest pack in its size class, the heavily featured Atmos 25 will satisfy many who prefer multi-compartment based packing over the one-sack style. The Atmos 25 has a total of six exterior pockets and two interior bladder pockets, in addition to the main pack bag.

Osprey makes water carrying easy with two separate water bladder pockets and two side panel water bottle pockets. The empty space behind the open mesh back panel is zipper accessible from inside the main pack bag to allow the insertion of a hydration bladder. You do not have to completely unpack to access it! Most 2-liter bladders fit well; 3-liter bladders are a little big. The hose runs out through the back panel access zipper and through a hose port at the top back of the pack. The bladder goes unnoticed in terms of size; however, drinking water temperature is affected by body temperature and vise versa. A second bladder pocket on the inside solves this problem but has other problems: the bladder takes up interior pack volume, it is a very tight fit, you have to unpack the main bag to get to it, and it snags on gear as you try to pack the main pocket. We see no reason for the internal hydration pocket.

The two side panel water bottle pockets will hold 1-liter bottles and have mesh drainage panels to allow excess liquid to escape. Unfortunately, these pockets are not accessible while wearing the pack. In addition, the lower side panel compression strap covers these pockets, making it difficult to remove items without loosening the straps. A hydration bladder is more convenient with the Atmos series; the side-panel pockets can be used to keep other essentials handy.

One feature on the Osprey Atmos 25 we really liked were the two zippered, mesh pockets located on either side of the padded hipbelt. One of these pockets is big enough for a small digital camera and mini-notebook, with the second a clear candidate for a bag of GORP or some energy bars. These two pockets, combined with a hydration bladder, greatly reduced the time we spent with the pack off, digging for items needed on the trail.

The large front "shove-it" pocket on our review samples is not as large as we would like. Nevertheless, it was useful for stowing a rain or wind jacket and has a grommet drained bottom. The folks at Osprey have enlarged the pocket for production packs. The release clasp for the shove-it pocket is difficult to work because it is firmly fixed onto the pack; a problem exasperated by a full pack. Above the shove-it pocket, there is a flat, zippered pocket lined with mesh towards the inside the pack. We found this pocket ideally suited for a map and compass, keys (there's a key clip on the inside) or other items one might need quick access to.

Although the main pack and all pockets have drain holes, some of the fabrics used in our pre-production samples held water. The padding in the shoulder straps and hipbelt retained a lot of water after an all day California monsoon. It took 24 hours for them to dry out.

The Osprey Atmos 25 has two ice axe loops and a convenient means to secure the handles at the top of the pack. A small piece of shock cord, with a specially designed hook on one end and toggle on the other, quickly attaches and tightens the handles to the upper back panel. This arrangement works equally well for unused trekking poles.

Two compression straps on each side panel (total of four) compress the load into a dense, secure load. The upper two fasten with side release buckles for easy access to the main zippered pack bag. Because they quick release, these upper straps can conveniently secure long items extending from the side pockets like tent poles or a fishing rod.


It is premature to fully assess the durability of the Atmos series packs. Osprey provided pre-production review samples with an understanding that the fabrics to be used in the production packs would be different. After using these packs as built, lighter fabrics are appropriate as the fabrics we tested are virtually bombproof by lightweight standards. Other construction details are as we have come to expect from Osprey. Seam failure is unlikely as every seam is double or triple stitched and high stress seams are bar tacked. These packs are nicely assembled; details that exude the exactness of computer aided design.


If features, packing convenience, and an airy harness are high on your list of necessities, the Osprey Atmos 25 makes for a great value, despite the 25-pound carrying limit. For those who prefer the weight savings of reduced features, the Atmos 25 becomes much less appealing at $139.

Recommendations for Improvement

Our recommendations here should not overshadow how great this new pack line is. The Osprey Atmos 25 is an excellent pack as tested. As a bonus, its flexibility conforms nicely to the female physique.

Lighter fabrics are appropriate (Osprey has already done this in the production packs) as well as other changes that would decrease weight without lost usability. We recommend omitting the interior hydration pocket from the design. It is a tight fit for a full bladder and there is considerable loss of interior volume when the pocket is used. In contrast, we found slipping a bladder into the back panel pocket was easier and concentrated the weight close to one's back.

Make the "shove-it" pocket larger by extending its height up to the zippered back pocket, perhaps down an inch or so, and then either remove the clasp for it or make it more flexible to ease access.

Use materials for the shoulder straps and hipbelt that absorb and retain less water.

The following change is less critical since it is difficult to stuff more than 25 pounds into the Atmos 25 even with a fair amount of water. The hipbelt is uncomfortable with loads above 25 pounds because it distributes more weight to the lower edge than the top edge. The angle at which the hipbelt is attached to the back panel should be closer to perpendicular to lessen this problem. The shoulder straps cause some discomfort at weights above 30 pounds. The placement might be slightly too wide (perhaps 1/2 inch total) causing the shoulder straps to place pressure on the shoulders, rather than draping over the collarbone.


"Osprey Atmos 25 Backpack REVIEW," by Jay Ham and Alison Simon. (ISSN 1537-0364)., 2005-03-15 03:00:00-07.