testing the hyperlite mountain gear unbound backpack for review

Hyperlite Mountain Gear Unbound Backpack Review

The HMG Unbound 55 & Unbound 40 are more dialed in versions of the 3400 & 2400 Series

The new Hyperlite Mountain Gear Unbound 55 Backpack and Hyperlite Mountain Gear Unbound 40 Backpack both deliver a small but notable suite of design and feature upgrades to their already best-in-class packs. This is a seriously great backpacking pack.

Hyperlite Mountain Gear Unbound 40 Stats

  • Weight: 30.1 oz
  • Price: $369
  • Materials: Dyneema. DCH 50 top DCH 150 bottom
  • Frame: Contoured aluminum stay, 1/4″ foam back panel
  • Load Capacity: 40 lbs
  • Internal Volume: 40L
  • External Volume : 9L
  • Pros: Waterproof. Indestructible. Ultralight. Excellent pockets. Good volume adjustability.
  • Cons: Expensive. No slack in rear exterior pockets when pack is fully loaded.

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Hyperlite Mountain Gear Unbound 55 Stats

  • Weight: 31.0 oz
  • Price: $399
  • Materials: Dyneema. DCH 50 top DCH 150 bottom
  • Frame: Contoured aluminum stay, 1/4″ foam back panel
  • Load Capacity: 40 lbs
  • Internal Volume: 55L
  • External Volume : 9L
  • Pros: Waterproof. Indestructible. Ultralight. Excellent pockets. Good volume adjustability.
  • Cons: Expensive. No slack in rear exterior pockets when pack is fully loaded.
hmg unbound backpack pack up and ready for hiking

HMG Unbound 40 & 55 – Testing

We’ve had our hands on the Hyperlite Mountain Gear Unbound 40 for about a month now. Initial testing confirms this is an excellent backpack. We took it out on a 20~ mile overnight and there were no major issues. Nothing rubbed, chaffed or failed. The XL side pockets proved to be the favorite new feature within the HMG pack family.

HMG Unbound 40 & 55 – Construction

As a baseline for understanding the Hyperlite Mountain Gear Unbound 40 & 55, start by imagining one of their other backpacking packs in the 2400/3400 series, like the Southwest, Windrider, or Junction. Unbound 40 is the exact same size as a 2400, and Unbound 55 is the exact same as a 3400, but they’ve now switched between cubic inches and liters in their naming conventions. Liters are preferable, so we hope this switch sticks around.

Like its predecessors, this is a Dyneema Composite Hybrid (DCH) construction. The fabric is super durable and waterproof. Think of it like a drybag attached to a pack frame with lots of external pockets.

But Hyperlite Mountain Gear Unbound 40 & 55 takes on a more boxy and less rounded shape. That’s because the back, front, and sides are each their own panel, rather than a single sheet of DCH which, on previous packs, formed more of a cylindrical shape when full. Adjacent panels are sewn together with some seriously burly trim and the interior is seam taped. It’s all well-made and very durable looking.

It’s still unclear to us if the switch to a paneled rectangle shape has any tangible advantages in the backcountry, but it does allow for a series of orange daisy chain loops to be bar tacked along the trim. On both sides of the pack, cinchable shock cord creates a compression web and/or exterior strapping options.

The Hyperlite Mountain Gear Unbound 40 frame has only one aluminum stay instead of two, but it feels burly enough to transfer weight and the pack is comfy. The padded hip belt has been given a bit of extra cushion and the pockets might be a tad bigger. The shoulder straps are as excellent as they’ve always been and have attachment points for extra storage.

hyperlite mountain gear unbound back panel

HMG Unbound 40 & 55 – Pocket Upgrades

Where it gets really exciting is the pocket upgrades! The center back pocket is made with a new material – Dyneema Stretch Mesh. And it seems like a great choice. You get the stretch of mesh with the durability and water resistance of Dyneema. Kind of a best of all worlds, though less breathable/sheer than the netting on Windrider, and less durable/water resistant than the Dyneema hardline on Southwest.

The main exterior rear pocket is also a couple inches taller than on prior HMG packs and the size upgrade is welcome. What’s more, the stretch mesh pocket panel continues wrapping underneath the bottom of the pack. The gap it forms with the bottom of the pack body creates a pocket space that we haven’t seen before. So far, this has been an excellent place to store a wet/dirty ground cloth.

There is also a secondary center back pocket doubling over the lower half of the taller main center back pocket. More exterior storage is always welcome with us, and Hyperlite Mountain Gear Unbound 40 & 55 delivers in a big way.

The side pockets are notably poochier and more voluminous. They can fit two smartwater bottles each. This is a nice upgrade, because as the pack fills up, it tends to eat into the useable volume of the exterior pockets. Each side pocket has a cinch as well, so you can secure the load.

While not a pocket per se, the top Y-strap is present as always, and great for compression or storing bulky items on the outside.

Lastly, one drawback to the stretch mesh rear pockets is that they have very little slack when the pack is loaded. So most of that pocket’s volume is derived from stretching the material to make extra room, rather than extra room being present via excess fabric.

HMG Unbound 40 & 55 – What could be better?

To be clear, this is an awesome backpack. It’s difficult to find major flaws, but we do have a few nitpicks.

For starters, we wish the external pockets had a bit more slack. If the interior of the pack is fully loaded, it will reduce the exterior pocket volume, which is taught, and doesn’t have much much volume of its own without stretching the fabric. Without stretching the material, the rear exterior pocket has virtually no volume of its own. All of the volume is derived from stretch. The lower outer back pocket is virtually unusuable if the pack is full and larger primary back pocket is full.

And on the pocket note, it would be nice if the wrap around pocket on the bottom of the pack had a buckle or closure system, it seems like something might fall out. That said, if you fill it enough that the stretch fabric is pulled taught, it holds gear remarkably well and quite securely.

The roll top closure, shoulder strap, and hip belt buckle hardware all shrank. They are a bit harder to use now, but still plenty functional. Still early days, but we suspect that we will end up preferring the burlier old buckles.

While testing, we worried about a potential rubbing point, but it wound up being a non-issue. But still, something to lookout for/could be better. This is where a seam connects the inside of the bottom pocket to the bottom of the backpanel. It feels abrasive and pokey, and could rub depending on where the bottom of the pack meets your upper butt.

close up on hyperlite mountain gear unbound backpack aluminum stay frame

Regarding Weight & Size

While there are lots of small feature upgrades, this is not a weight-savings upgrade. The weight of the Hyperlite Mountain Gear Unbound 40 is identical to the weight of the Southwest 2400. We’re not sure what, but it does seem some weight savings could have been found, considering how much of their base model was redesigned.

Lastly is size. This complaint only applies to the 40L model. While the Unbound 40 is the perfect pack to carry a dialed in ultralight kit, it’s a bit on the small size for the average backpacker. And even ultralight backpackers like ourselves can appreciate a bit of extra space. It means less backpack Tetris and fewer over-compressions of down garments and sleeping bags.

We feel that bigger packs are far FAR more user friendly for a very minor weight penalty. The Unbound 55 is less than one ounce heavier than the Unbound 40, while providing 15L extra space that can simply be rolled down when not needed. That’s a massive increase in usability and versatility for an extremely minor weight penalty.

As such, we would recommend the Unbound 55 over the 40 to 99% of people.

hyperlite mountain gear unbound 40

Hyperlite Mountain Gear Unbound Vs Southwest Vs Windrider Vs Junction

  • Favors Unbound

    • Seemingly better overall pocket configuration. More pockets, bigger pockets, stretchier pockets,
    • shock cord cinching seems to be more user friendly than nylon webbing straps for volume compression
    • lots of daisy chain loops for clipping and tying stuff to, though we don’t plan to use them much
    • Removable, reverse pull hip belt that is also more cushioned.
  • Neutral

    • Same weight as equivalently sized series
    • same shoulder straps
    • Same Y-Strap
    • Same DCH waterproof durable fabric
    • Available in white DCH 50/150 and black DCH 150
  • Favors Southwest, Windrider, Junction

    • the pockets aren’t stretchy, but have natural slack creating excess space without requiring any stretch
    • Southwest, Windrider, and Junction have larger heavier duty buckle hardware.
    • Southwest and Windrider are also available in the 4400 (70L) size which is preferable for winter camping, expeditions, and bear canisters.
    • Unbound feels very durable, but technically has more seams, failure points, plastic bits, etc.
HMG Unbound backpack side pocket close up

Hyperlite Mountain Gear Unbound 40 & 55 – Verdict

While this pack is still new to us and we will test it this season, it seems like an absolute banger after the first trip out. It takes what was already our favorite pack, with incredible durability and waterproofness, and mostly upgrades the pockets without much downside to weight or cost.

Compare the Hyperlite Mountain Gear Unbound 40 to more great options in our guide to the best ultralight backpacking backpacks of the year.


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