Most lightweight technical backpacks compensate for the different shapes of听various human torsos by incorporating a degree of flexibility into their frames. That works fine if you鈥檙e only asking that pack to carry a couple dozen pounds. But听the flexibility that makes them broadly comfortable also places a hard limit on the amount of weight they鈥檙e able to carry. If you need a pack capable of hauling 100 pounds or more,听you need a frame that won鈥檛听flex under that load but will carry听weight听as close to your back as possible. And that鈥檚 a problem, because humans do not come in a uniform shape or size.
How Backpacks Work
I have a curved back. If I stand against a wall,听with my heels and shoulders pressed against it, I can fit my hand between my lower back and the wall.听Most of my friends have straighter backs. But if we want to go backpacking together, I can loan them one of my Osprey packs ($155 and up), safe in the knowledge that they鈥檒l be comfortable with听it, too. 听comfort for most people by using a mesh suspension system that holds the pack away from the wearer鈥檚 body, along with a metal wire frame that can support anywhere from 25 to 85 pounds, depending on the model. It听will start to flex if the wearer really cranks down on the adjustment straps听or if the pack is loaded beyond its weight rating. This works really well.
A single backpack听is able to fit most people comfortably, while hauling as much weight as they likely need to to enjoy a simple camping trip. It doesn鈥檛 matter if one person鈥檚 shoulder blades poke out more than another鈥檚, the taut mesh will simply adapt to either person鈥檚 contours, and the wire frame will compensate for any dramatic differences. But not all outdoor activities can be accomplished with a 25-to-85-pound load. The point of a backpack frame is to transfer weight vertically into the hipbelt. If that frame flexes, it begins to pull at the wearer鈥檚 shoulders, becoming uncomfortable听and imbalanced. So听if you need to carry a lot of weight, you need a pack frame that can support that weight without flexing at all.
This is actually something that old-school, external-frame packs excel at. A big rectangle made from tubular steel is very strong. But听old external-frame听packs have two inherent design flaws: (1) a big metal rectangle can鈥檛 conform to the shape of a human body, so听it needs to be separated from the wearer鈥檚 back, and (2) that space means the wearer ends up carrying听a hanging load several inches behind their back, pulling at their shoulders.
To really carry weight comfortably, a pack frame needs to sit flush with your back, while also being utterly inflexible. Consider the varied shapes humans come in, and I鈥檓 sure you can see the problem. Wearing weight-hauling packs designed for flatter backs听than my own doesn鈥檛 just create discomfort, it also pulls my torso into an unnatural position, which can make it it difficult to breathe on steep uphills. That鈥檚 been a major issue for me, especially when I鈥檓听carrying a hundred pounds or more of meat out of the woods.
Enter , a small company based in Bozeman, Montana,听that鈥檚 been making packs and other high-performance hunting gear since 2012.
High-Tech Materials
By drawing resin-coated carbon fibers through a heated die听under pressure, the company is able to manufacture听a solid carbon-fiber stay that matches the contours of a human back. Stone Glacier employs four of those stays to听in听its ($365), which听fits curved听backs like mine. (The brand鈥檚 ,听$365,听is designed for people with straight backs.)听We all know that carbon fiber is light, but few companies go through the effort of producing products听from it that also take full advantage of the material鈥檚 strength.听Stone Glacier has tested its backpack frames to 340 pounds with no cracking or deflection in the stays. The only thing stopping the company from finding the failure point for its packs has been听the inability of听a human tester to lift a heavier load onto their back. The X-Curve weighs three pounds.
Like the other, straighter听frames in Stone Glacier鈥檚 lineup, the X-Curve incorporates a load shelf made from X-Pac, an extremely strong but听very light laminated composite fabric. Two of the carbon stays are arranged vertically, with the other two forming an X between them; this not only facilitates proper distribution of weight vertically, down into the hipbelt, but it also prevents sideways distortion, as the load shelf carries all that weight. That shelf attaches to the frame with one-inch webbing at 12 points. It enables Stone Glacier鈥檚 frames to be used on their own, without a pack body, with any of the packs in the brand鈥檚 range, or with one of those bodies听and a drybag, enabling you to move gear or meat around in a variety of ways.
I鈥檝e been running an X-Curve paired with Stone Glacier鈥檚 ($219). That pack听only provides 31 liters of interior volume (along with a six-liter external pocket designed听to accept a spotting scope). That鈥檚 not enough volume for even a quick overnighter, much less a multi-day backcountry trip, so I add 听to the load shelf听between the pack body and frame. The pack itself stows听a couple layers听and the other equipment I need during the day, while all my camping gear and food fits in the drybag. Arranged like that, I can hang the drybag in a tree at a campsite, then spend the day chasing animals around听without being encumbered by an unnecessarily large or heavy pack body. Switching between the two setups takes mere seconds. Made from very strong, extremely water-repellant 500-denier Cordura, the Approach 1800 weighs 1.1 pounds.
A Custom Fit
Stone Glacier鈥檚 frames incorporate three customization features that massively aid comfort. The first are the hook-and-loop panels used to attach the shoulder straps to the frame. Seventeen percent stronger than Velcro, the material spans 24 square inches of contact area between each strap and the frame, granting each strap the ability to resist up to 400 pounds of shearing forces (which is a complicated way of saying it鈥檚 not going to come loose). It also gives you near infinite levels of adjustability when it comes to听strap length and angle. In addition to my curved back, I also have a shoulder that sits lower than the other one, thanks to a motorcycle crash. The hook-and-loop connection allows me to compensate for that.
The other customization features are on the hipbelt. The lumbar pad is filled with several pieces of foam, which you can remove, reorganize, or relocate, allowing you to adjust its thickness, shape, and height. As you鈥檇 expect on a pack designed听to carry an immense amount of weight, the hipbelt is also extremely burly. Two one-inch webbing straps run along each side of the belt, so it sits听just above and below your pelvis鈥檚听iliac crest. The straps听also allow you to adjust each side of the hipbelt individually, top and bottom, creating听a perfect cradle for that protrusion鈥檚 unique shape and location on your body.
In the Mountains
During the fall, I听carried this pack on two weeklong backcountry hunts听and probably a dozen daylong excursions. It鈥檚 been up and down the same mountain at least 20 times听and supported my load over 20 trail miles听in a day in听the mountains of southwest Montana. The only big game I鈥檝e shot so far ended up being about a mile from my truck, so I just bear-hugged that mule deer for the slog out. But while I have no doubts that the X-Curve will haul an elk quarter just fine, the surprising conclusion after all that use is that I don鈥檛 think I鈥檓 going back to wearing lighter packs once hunting season is over. Stone Glacier鈥檚 pack听isn鈥檛 just better at hauling loads than ultralight alternatives; that curved frame听and its customization features make it more comfortable, too, even with only a couple pounds onboard.
Is this pack right for you? Unless you鈥檙e also participating in an activity like hunting听that necessitates the ability to carry a hundred pounds or more, you probably don鈥檛 need to spend over $600 to achieve a setup like the one I鈥檝e detailed here. My recommendation for Osprey鈥檚 range of packs remains unaltered, and you鈥檒l find them plenty comfortable听no matter your shape or size. But听if you are a hunter, I can help you justify that expense. Not only will a secure-fitting听Stone Glacier pack听work during the fall, but you鈥檒l also end up carrying it the rest of the year and for many years to come.