The Hyperlite Mountain Gear Unbound 40 Backpack is an ultralight backpack weighing 30.1 oz (853g) made with Dyneema DCF. Design-wise, it’s a pretty radical departure from Hyperlite’s past backpacks with large side pockets, a redesigned and replaceable hip belt, the use of a single frame stay and not two, back padding, daisy chains along the sides, a roll top stiffener, a stretch mesh front pocket, and one on the bottom. Net, net, these new features provide an extraordinary leap forward in the utility of Hyperlite’s backpacks, they make them much more flexible to use, and suitable for year-round hiking and backpacking. We did experience one issue with the new frame/hipbelt combination which we note below. It’s also worth noting that Hyperlite has started using liters to denote backpack capacity with the Unbound 40, rather than cubic inches, a welcome change that makes them easier to compare with backpacks from other companies.
Specs at a glance
- Color: White or Black
- Weight: (White: 30.1 oz /853 g ) (Black: 32.2 oz / 914 g )
- Actual Weight Tested: 30.6 oz in a Large torso/Large hipbelt
- Gender: Unisex
- Volume: 40L internal storage, 9L external storage
- Sizing: Multiple torso and hipbelt lengths
- Frame: Contoured aluminum stay, foam back panel
- Pockets: 6 (2 side, 1 front, 1 bottom, 2 hip belt)
- Hydration Compatible: No
- Material: Dyneema DCF and Dyneema Hardline (Nylon) (Black is more durable)
- Seam-taped: Yes
- Bear Canister Compatibility: BV500 and BV475 Vertical Only; BV450 and BV425 Horizontal or Vertical.
- Pros: Effectively waterproof, good pockets, multiple torso lengths, excellent attachment points
- Cons: Pricey. Hipbelt slippage. The front stretch pocket could be larger.
- Visit Hyperlite Mountain Gear for complete specs.
I’ve been testing the Unbound 40 in New Hampshire’s White Mountain National Forest, “where backpacks go to die,” since November 2022, through late autumn, winter, and into this spring. I’ve hiked approximately 150 miles with it including a 1-night overnight. I’ve been using backpacks from Hyperlite Mountain Gear (HMG) since 2013 and the HMG Southwest 40 and HMG Southwest 55 are two of my favorites having seen extensive use throughout the Whites, on the Appalachian Trail, and in Scotland. For a detailed breakdown of HMG’s packs (that makes their somewhat confusing product line understandable), see Hyperlite Mountain Gear Backpacks: How to Choose.
Backpack Pockets and Storage
The Unbound 40 is a rolltop backpack that can be buckled together on top or along the sides of the pack using provided accessory cords that attach to daisy chains on the pack sides. Those cords are easy to lose though (I lost one when it fell off), but it’s still a nice option since it gives you the ability to apply much better compression to the top of the pack, in addition to the included Y-strap.
Unlike HMG’s other backpacks, there is no velcro strip on the top of the rolltop, which is a good thing because it is one of the first points on HMG packs to break down and unravel with use. It’s been replaced with a stiffener.
The Unbound comes with huge side pockets that are great for storing multiple bottles and make a convenient place to hold the bottom of a snowshoe if you hike in winter – this has always been a bit of a challenge with HMG’s other backpacks. The top of the side pockets has an elastic cinch cord for securing the contents. The Unbound does not have an internal hydration pocket or hydration ports, so you’ll need to carry water in these pockets or in accessory sleeves attached to the shoulder straps.
The hipbelt pockets are similarly large and can easily fit a Smartphone and snack bars or gloves. HMG expanded its hipbelt pocket size a few years ago, so this isn’t a net new change.
The pack also comes with two open stretch mesh pockets, one on the front and one on the bottom of the pack, which is a feature that’s become popular with thru-hikers. The front mesh pocket is pretty unique in that it has a top opening and a lower one near the bottom. However, it becomes increasingly difficult to use, as in tight, when the interior of the pack is stuffed full of gear.
I don’t think it’s a tremendously functional enhancement, but it gives you a way to access items at the base of the front pocket without unloading everything in the pocket. For example, I keep my tent stakes at the base of the front stretch pocket and this lets me access them easily.
The Unbound also has a stretch mesh pocket on the bottom of the pack that can be a convenient to place to store snacks, hats, and gloves as long as you don’t mind crushing the contents or getting them wet when you take the pack off and put it on wet ground or in the mud. It has two openings, one on the right when facing forward and a small hole on the left, called a trash port so you can stuff used wrappers into it. It can be hard to access the openings however if you have bottles in the side pocket pockets, which hang down and prevent access unless they’re pushed up and out of the way.
Backpack Frame and Suspension
The Unbound40 has a single contoured aluminum frame stay augmented with foam padding behind the shoulder straps for increased comfort, something that HMG includes on their higher volume models today. That frame stay terminates in the pack bag but is not connected to the hipbelt in any way, which is a little bit of a head-scratcher, to be honest.
The hipbelt, in turn, is no longer sewn to the pack bag as in HMG’s other backpack models but is removable and attached to the pack with velcro, which I think it’s a net loss in terms of load transfer to the frame. In testing, I also experienced repeated hipbelt slippage down my hips using the Unbound40 hipbelt, something I’ve never ever experienced with HMG’s other backpacks. Your mileage may vary since your hip shape may be different from mine, but this hipbelt slippage raised a red flag for me.
The hipbelt webbing doesn’t slip, so I’ve eliminated that as a possibility and the hipbelt padding on the UnBound seems identical to what’s used on the HMG’s older backpack models. I suspect that the base of the pack collapses when carried, exacerbated by the fact the pack bag and the hipbelt are now decoupled, creating extra slack in the hipbelt enabling the slippage to occur. I repeatedly found myself carrying the pack weight on my shoulders alone, which is most unpleasant and tiring.
Another notable difference in the UnBound hipbelt compared to HMG’s other models is that it is tensioned by pushing the straps forward, using what’s called a Scherer cinch, which was first introduced by Kelty some 20 years ago and is in use on most Osprey and Gregory backpacks. The center buckle size has also been reduced, but it doesn’t clog with snow, which is a problem with many packs with smaller buckle hardware. While there are two tiers of straps on the hipbelt that you’d hope would conform better to different hip shapes, I didn’t experience much value in their use.
The shoulder straps on the Unbound, like HMG’s other packs, are J-shaped, which are less comfortable for women and men with well-developed chests because they don’t conform to curves very well. They are covered in front with daisy chains at least, so you can easily attach accessory best-of-breed pockets, like the HMG shoulder strap pocket shown here, bottle sleeves, or electronics to your shoulder straps.
External Attachment Points and Compression
The Unbound has dual daisy chains sewn along the side seams of the main compartment which can be used to add cords or webbing so you can hold or secure bulky gear, like a foam pad, Tenkara fishing rod, or snowshoes, that won’t fit inside the backpack. Doing this is much more challenging on HMG’s other backpacks so these daisy chains are a big upgrade in ease of use.
The side daisy chains are colored orange but only run to the top of the front stretch pocket: still that is the sweet spot in terms of value. Elastic cords are supplied with the pack to help secure items with the daisy chains, but you’re free to rig up your own as well. There are also short daisy chain segments at the base of the front mesh pocket and on the front and back sides of the hip belt pockets.
Comparable Ultralight Backpacks w/Frames
|Make / Model||Weight||Fabric|
|Zpacks Arc Haul 60L||20.9 oz / 593g||Ultra 200|
|Hyperlite Mountain Gear Southwest 55||34.9 oz / 989g||Dyneema DCF|
|Granite Gear Crown 3 60L||32.6 oz / 1040g||Robic Nylon|
|Osprey Exos Pro 55||34.6 oz / 981g||UHMWPE Nylon Ripstop|
|ULA Circuit 68L||37.3 oz / 1038g||Robic Nylon|
|Gossamer Gear Mariposa 60L||30.5 oz / 865g||Robic Nylon|
|REI Flash 55L||45 oz / 1276g||Robic Nylon|
|Gregory Focal 58||41.3 oz / 1171g||Robic Nylon|
|Waymark Gear Lite 50||34.8 oz / 987g||EcoPak EPX200|
|Atom Packs Mo EP50||32.1 oz / 910g||EcoPak EPX200|
The Hyperlite Unbound 40 and the new larger Unbound 55 are well matched versus these backpacks, which are also available in multiple volumes, in addition to those listed. Of these, I’d pay particular attention to the Granite Gear Crown 3 60, the Waymark Gear Lite 50, the Atom Packs Mo EP50, and the HMG Southwest 40/55 which are the closest in terms of features and frame/suspension.
The Hyperlite Mountain Gear Unbound 40 is an excellent ultralight backpack for multi-day backpacking trips with lightweight loads and excels across a wide range of trail conditions and gear requirements. It’s also substantially different from the other hiking and backpacking packs that Hyperlite makes and hopefully the start of more upgrades across the pre-existing product line. The biggest benefit of using the Unbound vs Hyperlite’s other backpacking backpacks is an increased emphasis on external storage with larger pockets and external attachment points. In particular, the daisy chains sewn to the side of the backpack make it much easier to attach bulky gear while the front and bottom stretch mesh pockets provide more secure and accessible storage. The only problematic element of this pack is that the hipbelt is decoupled from the frame stay resulting in loss of load transfer and potential hipbelt slippage. I’d be curious to hear if others have experienced that issue besides myself.
Disclosure: HMG donated a backpack for review.SectionHiker is reader-supported. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.