The Osprey Mutant 52 is a top-loading alpine-style backpack made for winter backpacking, climbing, and backcountry ski tours. Like many winter-specific packs, it is highly modular and can be stripped down to save weight, with a removable top lid, hip belt, and frame. Reinforced ski loops, haul loops, hip belt gear loops, daisy chains, wand pockets, and ice tool holders make the Mutant 52 easy to use if you like the cold and snow. New this year, the Mutant 52 is a higher volume version of the popular Mutant 38 backpack and replaces the Variant 52 (now heavily discounted) in Osprey’s winter backpack line.
Specs at a Glance:
- Volume: 52 liters
- Gender: Unisex
- Total weight:3 lbs 8 oz (size M/L)
- Removable components
- Top lid: 5.5 oz
- Helmet carry: 1.8 oz
- Hip belt: 7.3 oz
- Plastic frame sheet: 7.9 oz
- Pair of aluminum stays: 1.4 oz each
- Frame: Internal
- Torso length sizing: S/M 16 – 19 in; M/L 18-22 in.
- Materials 210D High Tenacity Nylon, 420HD Nylon Packcloth
- Maximum recommended load: 45-50 Lbs.
Backpack Storage and Organization
The Mutant 52 is a streamlined top-loading backpack with a floating top lid and a main compartment that closes with a drawstring. While there are wand pockets on both sides of the pack, the pack lacks side water bottle pockets or a front stuff pocket on the pack, in line with its minimalist winter character. While the lack of external storage makes the pack more durable for hauling up cliffs, it changes how you’ll use the pack since you the only way to open it is to pop the lid and dig around in the main compartment. This isn’t necessarily bad on a winter pack, but more a matter of preference.
The floating top lid is attached to the top of the pack with plastic buckles and webbing straps, making it easy to remove if it’s not needed. Floating lids are a great option on winter packs because you can sandwich bulky gear like ropes, tent bodies, or pads between the lid and the main compartment if you need to carry extra gear on approach hikes. This isn’t the kind of gear you can fit inside a backpack easily. If you don’t need the top lid or want to reduce the weight of the pack, the Mutant 52 comes with a permanently attached speed lid (Osprey calls these flap jackets) that covers the hole over the main compartment instead.
The top lid has two pockets. A cavernous, zippered main pocket (with a key fob) that’s big enough to store multiple pairs of gloves, hats, maps, and navigation equipment. There’s also a second smaller pocket that contains a helmet carry net that can be attached to the top of the lid (if used) or attached to the daisy chains on the front of the pack. This small pocket is large enough to hold a GPS or Personal Locator Device, smartphone, or camera and a handy place to stash stuff.
The main compartment has a hydration pocket inside and hooks to hang the bladder, making it easier to drink from. A single hydration port is located between the shoulder pads. There’s also a frame pocket where you can pull out the frame (a plastic sheet and w/ 2 aluminum stays) and a good place to stash a thin bivy pad.
Compression and External Attachment Points
The Mutant 52 has two tiers of side compression straps, which can also be used to secure gear to the sides of the pack. The top compression strap opens with a buckle, but the bottom doesn’t. This is a little less convenient for securing snowshoes to the sides of a pack, but still a workable solution.
There are reinforced ski loops positioned under the bottom compression strap, making it possible to configure an A-Frame ski carry together the top compression strap. That are also shallow wand pockets also on the pack sides, and a rope strap that loops over the main compartment.
The mutant comes with a universal ice tool holder system, including two shaft holders. A pair of daisy chains on the pack’s front and two more on the two lids let you attach additional gear to the pack, using carabiners, webbing, or ski straps.
The mutant’s climbing and mountaineering pedigree are also evidenced by a three-point haul system, good for winching gear up cliffs and to portaledges.
Backpack Frame and Suspension
The Mutant 52 in an internal frame backpack with a stiff plastic sheet and two removable aluminum frame stays, so you can adjust the degree of stiffness you want. The aluminum stays can also be custom-shaped to fit body shape if desired. The pack also has load lifters, which are particularly useful on pack designed to haul heavy gear. The entire frame system is removable if you want to save gear weight. Tightly packed gear can often compensate for the lack of a frame, at least in terms of pack bag stiffness, or you can drop a foam pad into the main compartment and pack your gear inside it (like a donut) to create the same effect.
The shoulder pads, back of the pack, and hip belt wings are lightly padded with foam and provide minimal cushioning to help keep the pack weight down. The shoulder pads are minimally outfitted with two hydration hose keeper loops and an adjustable sternum strap with a daisy chain height-adjustment system. The padded area behind the shoulder straps contains a foam bivy pad that you can kneel or sit on in a pinch, but it’s pretty tough to remove if you wanted to replace it.
The hip belt comes with gear loops instead of pockets to rack gear with carabiners. It can be folded back around the front of the pack if you’re wearing a climbing harness or completely removed since it’s attached to the pack with velcro. Hip control straps, at the rear of the hip belt, help pull the bottom of the pack closer to your hips for better control. The hip belt closes with a single beefy buckle, using pull forward straps for mechanical advantage. The one thing missing on the Mutant 52 hip belt is a simple webbing strap-style hip belt to help lock the pack to your hips when the full hip belt is not needed. Check out The North Face Phantom 50 Backpack, which has this feature, and is another good option for climbing and winter mountaineering.
Comparable Winter Backpacks
|Make / Model||Weight||Floating Lid||Crampon Pocket||Hip Belt Loops||Ski Carry|
|The North Face Cobra 60 L||57 oz||Y||Y||Y||Y|
|Gregory Denali 75 L||72 oz||Y||-||Y||-|
|The North Face Phantom 50 L||40 oz||Y||-||Y||Y|
|Black Diamond Mission 75 L||64 oz||Y||Y||Y||-|
|Cold Cold World Chaos 66 L||60 oz||Y||Y||Y||Y|
|Exped Lightning 60 L||41 oz||-||-||-||Y|
|Hyperlite Mountain Gear Ice Pack 70 L||37 oz||-||Y||Y||Option|
|Mountain Hardwear AMG 55||74 oz||Y||Y||Y||Y|
|Osprey Mutant 52 L||55 oz||Y||-||Y||Y|
|Sierra Designs Flex Capacitor 60-75L||42 oz||-||-||-||-|
The Osprey Mutant 52 is an internal frame winter backpack that’s more optimized for climbing and mountaineering than general-purpose winter backpacking use. The 52-liter volume is on the small side if you need to pack a winter tent and cold weather sleeping bag, although quite doable if you’ve refined your winter gear list to be as compact as possible. While the Mutant 52 has a quite respectable external attachment system, the pack’s frame and load carrying capabilities are where it really shines. The combination plastic frame sheet and pair of aluminum stays make it possible to carry 40+ pound loads with ease, while the minimal shoulder strap and hip belt padding make the pack highly responsive when skiing or climbing.
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