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Hyperlite Mountain Gear Unbound 40 Backpack Review

Hyperlite Mountain Gear Unbound 40 Backpack Review

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. 

Testing Process

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 rolltop can be buckled together on top or along the sides with provided accessory straps.
The rolltop can be buckled together on top or along the sides with provided accessory straps.

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 side pockets can hold multiple bottles.
The side pockets can hold multiple bottles.

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 side pockets are large enough to hold the bottom of snowshoes.
The side pockets are large enough to hold the bottom of snowshoes.

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 hipbelt pockets are quite large.
The hipbelt pockets are quite large.

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.

You can access the contents of the front stretch pocket from the top or the bottom (red jacket).
You can access the contents of the front stretch pocket from the top or the bottom (red jacket).

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.

There is a stretch pocket on the bottom of the pack but it’s really best used in dry climates.
There is a stretch pocket on the bottom of the pack but it’s really best used in dry climates.

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.

Hyperlite Mountain Gear Unbound 40 Backpack


Ultralight Thru-hiking Backpack

The Hyperlite Mountain Gear Unbound 40 Backpack is an ultralight backpack weighing 30.1 oz (853g) made with Dyneema DCF. Designed for thru-hiking and backpacking, it's loaded with features that make it easy to use for all day hiking.

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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 Unbound has a single aluminum stay cushioned by foam padding.
The Unbound has a single aluminum stay cushioned by foam padding.

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 is replaceable and not sewn to the pack body like HMG’s other packs.
The hipbelt is replaceable and not sewn to the pack body like HMG’s other packs.

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.

The hipbelt tightens with push forward straps, which is new to HMG Packs.
The hipbelt tightens with push forward straps, which is new to HMG Packs.

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 front of the shoulder straps are covered with daisy chains making it easy to add accessory pockets.
The front of the shoulder straps are covered with daisy chains making it easy to add accessory pockets.

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.

There are dual daisy chains along the sides of the pack.
There are dual daisy chains along the sides of the pack that can be used to create compression straps or secure gear with cords (supplied).

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 / ModelWeightFabric
Zpacks Arc Haul 60L20.9 oz / 593gUltra 200
Hyperlite Mountain Gear Southwest 5534.9 oz / 989gDyneema DCF
Granite Gear Crown 3 60L32.6 oz / 1040gRobic Nylon
Osprey Exos Pro 5534.6 oz / 981gUHMWPE Nylon Ripstop
ULA Circuit 68L37.3 oz / 1038gRobic Nylon
Gossamer Gear Mariposa 60L34.2 oz / 968gRobic Nylon
REI Flash 55L45 oz / 1276gRobic Nylon
Gregory Focal 5841.3 oz / 1171gRobic Nylon
SWD UL Long Haul 5030.2 oz / 856gUltra 200
Durston Kakwa 5531 oz / 880gUltra 200

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.

Shop at Hyperlite


Disclosure: HMG donated a backpack for review.

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  1. Yep. I have the same hip belt slippage. Don’t know why they stopping sewing the hip belt on except to cut out mfg and make more profit. Shame.

    • Hmm, I’m not so sure about that. Other companies have removable hip belts so they can be replaced if they get damaged or if you gain or lose a lot of weight. Thru-hikers for example. Maybe HMG just missed the mark on their first attempt.

      I hope it doesn’t slip repeatedly after retightening? Is there just a lower max weight before slippage or loss of load transfer starts to occur?

      My new Unbound 40 just shipped so I’ll be testing it soon.

      • Slips repeatedly after tightening. I tied knots in the hip belt webbing to determine whether the webbing was slipping and it wasn’t. Other companies have removable hipbelts, but they slot the frame(stay) into the hipbelt or lumbar pad. This pack doesn’t.

        • I believe you. It’s strange though. I just checked my ULA Ohm, and unless I’m misunderstanding, the suspension hoop in that pack doesn’t seem to attach to the hip belt or lumbar pad either. I’ve had no trouble with slippage or load transfer with that pack. I wonder what HMG got wrong.

          It’s unfortunate. I had high hopes for the Unbound 40. Now I’m worried that I’ll have to return it and maybe stick with ULA, which wouldn’t be the end of the world.

        • The carbon fiber hoop in the Ohm is only there to keep the pack bag from collapsing in a heap. For all practical purposes the Ohm is a frameless pack, which is why ULA recommends keeping your base eight to 12 lbs for it. I happen to think the ohm is actually a great pack.

  2. I just received my Unbound 40 this morning. I loaded it up with 28 lbs and wore it around for about 30 min. Now I understand exactly what you describe. The weight just started to sag and got heavier and heavier on my shoulders. I tightened the hip belt until it became uncomfortable, but the weight kept sagging onto my shoulders.

    I moved the same 28 lb load into my ULA Ohm and what a difference! The Ohm carried that weight so much better and never sagged. It had the feeling of being 5 lbs lighter, even though I weighed both fully loaded packs and the Ohm was about 3 oz heavier.

    The hip belt on the Ohm felt much more secure and carried the weight without feeling too tight. I did notice that ULA puts velcro on both sides of their hip belt. They also run the velcro vertically instead of horizontally, like HMG. I wonder if the HMG hip belt is rolling or twisting under load, which is allowing the pack to sag?

    Regardless, I wouldn’t carry more than about 20 lbs in the Unbound 40 until HMG fixes this problem.

    • I really just think that the hip belt is not load bearing is the problem.

      • Ok, I think you’re exactly right. I’ve been playing with it for a little while and what you describe in your review is exactly what I’m seeing. The hip belt can move 1/2″ – 3/4″ because the frame stay isn’t tied into the hip belt and doesn’t extend to the bottom of the pack. There just isn’t enough structure there to keep the base of the pack from collapsing.

        I’ve reached out to HMG to see if they can come up with a solution, but this seems like a bad design flaw.

  3. Fascinating discussion. I have an HMG Headwall 55 which has a removable hip belt and 2 aluminum stays that run all the way to the bottom of the pack. I have never experienced this sagging. I also have an ULA Circuit which has an single aluminum stay (and carbon fiber stay) that is not directly connected to the hip belt (on this pack there is beefy velcro on both side of the hipbelt, and I do not experience this sag. Hmm !?!?

    • The ULA Circuit has a very pronounced lumbar pad, a wider hip belt, and one that truly wraps the hip bones – the combination rests on iliac crest and won’t budge. That lumbar pad is pretty rigid too and won’t buckle. (have one right in front of me).

  4. I wonder having the belt sewn in would fix it. I just bought the pack for trekking in the EU, and would want to mitigate that problem.

  5. Philip, How do expect to make any money if you keep telling the truth in these product reviews? Just kidding, I really value your integrity!

  6. I wish they would add load lifters.

  7. The Atom Packs The Mo hip belt is actually velcro’d into place – but it takes a major effort to remove (and replace) it. So far, I haven’t experienced any kind of “slippage.” AP did an excellent job with the “Mo”, transferring the weight to the hip belt given it’s low-key suspension system. All to say, maybe it’s not the Velcro, but how it was designed?

  8. The Unbound sort of reminds me of the HMG Dirigo 2, if anyone remembers that, which was just a total head scratcher from a company that should be positioned to put out a pretty good product.

    With the caveat that they are available in big box stores, there is no case to be made these days for an HMG pack. Why would you spend so much on a pack that is so uncompetitive?

    I have hiked fairly extensively (a few thousand miles) with a Southwest 2400 that I have owned since 2018. It is still my main pack, but I am finally getting rid of it this summer.

    Here are the major flaws with the Southwest / Windrider / Junction compared to the rest of today’s market:
    – No load lifters (why?)
    – Frame design is weak compared to competitors at similar or lower weights. I have experienced the pack buckling under loads around 30 pounds. Checkout Cam Honan’s recent review of the Six Moon Designs Swift X and he says basically the same thing about his HMG pack.
    – There are better, more comfortable hip belt designs out there (Atom Packs Mo, ULA packs, SMD, SWD, pick your poison)
    – The fabric they use is outdated, especially for the price. There are multiple better fabrics out there at this point. Still a good fabric, but it doesn’t justify a price premium over something like Ultra or EPX.
    – Weird / mostly unadjustable sizing. There are very few adjustments that you can make. A frameless pack is much more forgiving in terms of torso size, as is a framed pack with load lifters.
    I have a theory that their recommended sizing results in “too large” packs in terms of torso sizing, because you can make a pack that is too large work better than you can make a pack that is too small work. Compare this to something like a ULA Ohm or a SMD pack that lets you adjust the hip belt several inches, or to every other pack in the category that comes with load lifters.
    – Super basic J straps, no option for S straps

    • Why no load lifters? Because there is no benefit of load lifters on this pack. The shoulder take off points are mounted at the top of the pack, so the pack doesn’t sit low when properly sized; therefore, there would be no benefit or functional purpose for load lifters on the pack. If you notice packs that use load lifters, the shoulder strap take off points are mounted lower, so the shoulder strap actual curves a bit behind the shoulder lower on the back. The load lifters are attached at the apex of the shoulder to the top of the pack. HMG packs having the shoulder straps already attached to the top of the pack effectively negative load lifters, which are designed to bring the top closer to the back due to the lower take off point of the shoulder straps. If you follow HMG sizing correctly, when weighted, the take off point mounted at top of the pack should sit at the same shoulder strap apex level.

  9. I haven’t had hip belt slippage issues, but I don’t use the pocketed one that comes with the Unbound 40: I use the hip belt with gear loops, but use the removable hip belt with the gear loops. I dislike the big pockets because they aren’t one hand operation friendly. I opt for either a fanny pack, nothing or the shoulder strap pouch. I dislike the shoulder straps because I find them too close together. Put me in the barrel chested freedom fighter camp, or maybe a bit out of shape thus larger manoglands, but really its the mounting points that feel too close together. I hate that the HMG shoulder logo patch covers up the daisy chain loop I need on every pack. It’s a stupid position that technically voids the warranty because I have to cut it off to place the chest strap at the correct height. For some reason, HMG didn’t double back sew down the side compression strap end, so found mine on the ground having slipped out of the buckle even though the strap was double fed back in the buckle. Easy sewing fix, but odd that the other straps are sewn, but these aren’t. The front strap of the Y strap is sewn inside the exterior front pocket, which is annoying when using the front mesh pocket when it’s unbuckled. They could have mounted above the pocket like on their other packs. The small front exterior pocket is oddly shaped, with one end 3cm shorter than the other. There is no functional purpose for it, and it makes the pocket less useful. The bottom pocket with “garbage” stash does not comport with leave no trace behind, because you stuff garbage in their and it just goes out the gaping end, or if you have stuff stashed in the bottom adding garbage means you just pull out garbage with whatever you stuffed there. It’s a useless feature and would have been better to have both ends fully opened so you could actually like stuff a sleep pad or something. the side daisy chainwebbing are mismatched, with one side going higher and the other side going lower. Doesn’t make sense and limits overall usage/flexibility. Also in the doesn’t make sense category is lack of ice axe/pole loops retainers. You can add bungee attachments to the side and front horizontal daisy chain webbing, which is what I did, but come on, HMG couldn’t bother with $2 extra material. I’m a water bladder guy, so I’ve used Zpacks stickon molle loops to attach a ULA hydration sleeve that fits 3L bladder. I feed the tube out one side of the rolltop end and voila. I also use Zpacks stickon accessory pouch to provide some internal storage. The Zpacks stickon stuff does very well and I haven’t had any issues thus far. Since HMG Unbound 40 has the side daisy chains, I’m able to use the Zpacks top side mesh pockets. I also have the PackbackDesigns flash mesh zipperd pockets that work well there. I concur about the dyneema stretch mesh being a bit tight when things get stuffed inside the main compartment. I like many things about the Unbound 40, despite the nits and mods that I wish it had that I made. I’m also waiting on Vaucluse Gear Gen2 backpack ventilation frame, since I’m a sweaty pig and the DCH fabric just reinforces that fact.

    I do think HMG needs to beef up quality control, not to mention stopping their third party review filter spiking the punch bowl by not letting low star reviews on HMG’s website. My Unbound 40 didn’t come with a side bungee and pocket bungee was misrouted and some sewing issues. Having also purchased another pack and some other accessories recently, I’ve found similar QC issues. To HMG’s part, despite spiking the punch with stellar reviews, they are very quick to make things right.

    • HMG contacted me about the hipbelt slippage. They hypothesized that it was an error in how the velcro inside that holds the hipbelt was sewn.

      • I don’t really buy the logic of an error in how the velcro inside is sewn, more than the position of the velcro anchor and the amount of fabric slack. Although up to 40 lbs is asking a lot for a 1.5″ x 6″ strip of velcro which is more like 1.25″ x 5.75″ contact patch of pile and loop. Although I have experienced the belt slippage, I can see that when at load the bag sags down from the velcro anchor point because of the excess fabric slack. If the shoulder straps aren’t cinched down and the chest strap used, I can see the stay flexing more and pulling away from my back causing additional sagging from the velcro anchor point. I think you would still have the same issue if the hip belt were sewn in, because the sewing point would be the anchor point from which the slack would sag/pull down from.

  10. Thank you for addressing the harness/single stay for the Unbound. I’ve been searching for this exact information and folks tend to focus on the doo-dads than how the pack actually carries. I don’t understand why HMG reduced this pack to one stay. Assuming weight savings. I had a single stay pack years ago and eventually when the foam back pad compressed, the single stay would dig into my spine. I thought that per HMG’s website that there is a plastic sheet that the single stay is mounted too — at least their specs refer to a plastic sheet. But all
    Of the reviews I’ve read/watched just mention the foam back pad.

    Does your have the plastic sheet?

    The hip belt issue is another concern of mine. I watched a review on YouTube and the reviewer said the exact same thing — that the hip belt sagged. She went back to her Southwest pack because of it. As someone who is smaller in stature, I need all the help I can get from my hip belt to help support heavier loads on longer trips.

  11. I came upon this writeup a day late. I ordered 2 Unbound HMG backpacks the night before I found this. I ordered an Unbound 40 for my wife and an Unbound 55 for myself.

    The main reason that I was looking for another pack was do to slippage at my non-existent hips with my other packs. I have 2 Crown backpacks, an Osprey and a few others kicking around that are more specialty packs. I saw the HMG packs at REI and I tried on a medium Southwest pack and it was a perfect fit for my torso. I loved the position that the belt came in. A bit above my hips allowing the pack to settle in above my hips rather than having to squeeze a hip belt tight to keep a pack up. Without having to cinch up my shoulder straps to carry majority of the load. This gave me hope that I could get back to backpacking again comfortably. But, then this review.

    I emailed HMG and asked them if they have fixed the belt slippage issue, but I have yet to receive a response which is troubling to me after placing a $750 order for possibly defective products. Now I am back to being disillusioned about my prospects of comfortably backpacking. Do I order a Southwest which fits awesome and has a fixed belt. I certainly like the functionality provided in the new features of the Unbound over the Southwest, but if it provides the same old slippage then it does not matter. Any other packs I should look at? My use is weekend adventures and once a year a 7 to 10 day backpacking adventure. My load was consistently 30 pounds, but I am working on lightening up my gear and hope to get that down to closer to 25 pounds for warm weather adventures.

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