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Six Moon Designs Fusion 50 Backpack Review

The Six Moon Designs Fusion 50 has a unique frame system that lets it carry heavier loads than other ultralight-style backpacks.
The Six Moon Designs Fusion 50 has a unique frame system that lets it carry heavier loads than other ultralight-style backpacks.

Six Moon Designs Fusion 50 Backpack



The Fusion 50 is an ultralight-style pack with a unique frame than can carry heavier loads than most other lightweight packs. An adjustable torso and the availability of hip belts in multiple sizes makes is possible to get a near custom fit.

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The Six Moons Designs Fusion 50 (MSRP $230) is a lightweight long distance backpacking pack with an adjustable length frame and multiple-sized hip belts so you can dial in a custom fit for your body shape and dimensions. Weighing 2 pounds 14 ounces, the Fusion 50 is noticeably different from most other ultralight-style backpacks in that it is capable of carrying 35-45+ pound loads, a weight range where most ultralight backpacks fail miserably. While the Fusion 50 still handles lighter weight loads well, its ability to go heavy is exceptional.

Why would you ever need to carry that much weight? It’s actually pretty typical for long distance backpackers who need to carry 15 pounds of gear, 5 days of food, and water, or transitional hikers who are downsizing from heavier to lighter weight gear. If you’re looking for a UL-style adjustable-frame backpack that can go heavy or go light, be sure to check out the Six Moon Designs Fusion 50 or its big brother, the Fusion 65.

The Fusion 50 is a top-loading backpack with a roll top closure, good for providing top down compression for backpack loads
The Fusion 50 is a top-loading backpack with a roll top closure, good for providing top down compression for backpack loads.

Internal Storage and Organization

The Six Moon Designs Fusion 50 is a roll-top style, top loading backpack with 50 liters of internal storage in the pack’s main compartment and extension collar (combined). The chief advantage of roll top packs is that they’re lighter weight than packs with an additional top lid and that they provide highly functional top compression, which is useful for better load control. While they can be inconvenient and time-consuming to open and close constantly while hiking, most roll top backs come with a plethora of easily accessible external pockets for storing items that are used more frequently.

The 50 liter volume includes the main compartment plus the volume of the extension collar.
The 50 liter volume includes the main compartment and the volume of the extension collar. This is a bit different from other manufacturers who don’t count extension collar volume in their capacity specs.

On the Fusion 50, there are two pockets inside the main compartment: a hydration pocket held in place by plastic clips (that can be removed to save 1 oz.), and a small zippered pocket behind it, good for storing a passport, a thin wallet or keys.

More accessible, external storage is provided using a rear shovel pocket which is open on top, two solid zippered pockets in the hip belt, two small stretch pockets on the shoulder pads, and two side water bottle pockets. The latter are easily reachable when wearing the backpack.

The Fusion 50 has a rear shovel pocket and side water bottle pockets, partially covered by stretch mesh.
The Fusion 50 has a rear shovel pocket and side water bottle pockets, partially covered by stretch mesh.

The side water bottle pockets are generously sized and can fit two 1 liter water bottles or a Jetboil and water bottle.The top of the pockets can also be cinched tight with a drawstring to keep items from falling out.  The exterior of the bottle pockets is made with a dense stretch mesh and includes a fabric panel along the bottom (shown above) to help prevent abrasion when the pack is placed on the ground. The mesh won’t stand up to continuous off-trail use however, so use the Fusion on well-groomed trails only .

The rear shovel pocket is sized to hold bulky garments or gear like a rain jacket or wet tarp. Like the side bottle pockets, it has a cinch cord running through the top to secure it closed. I do wish this pocket has larger with a self-tensioning elastic closure for simplicity and have provided feedback to the manufacturer.

Front mesh pockets on the shoulder pads large enough to store bars or a phone
Front mesh pockets on the shoulder pads are large enough to store bars or small water bottles.

In addition, there are two open stretch pockets on the shoulder pads that are large enough to fit a small camera, meal bar, or small water bottles. The shoulder pad pockets are positioned rather high up on the shoulder straps, like pockets found on trail running vests or backpacks, and interfere with the daisy chains sewn to the front of the shoulder pads. I don’t particularly care for them, but many people like pockets like this.

The Fusion 50 has two tiers of side compression straps, both angled to pull the load closer to the hip pad and lumbar area.
The Fusion 50 has two tiers of side compression straps, both angled to pull the load closer to the hip pad and lumbar area. They also pull the sides of the pack away from your shirt for better ventilation.

External Attachment and Compression System

The Fusion 50 has an excellent external attachment and compression system that provides a lot of versatility for carrying different kinds of loads. While this an area where the pack is strong, the pack feels cluttered with a lot of compression and suspension-related webbing straps. It’s a tradeoff: sleekness versus versatility, that you need to be cognizant of when evaluating the Fusion packs. Many of the straps are also somewhat longer than they need to be and you may find yourself trimming them down which will also declutter the pack somewhat.

Here’s a complete list of the compression and suspension webbing straps on the Fusion 50:

  • Two tiers of side compression straps on each side of the pack
  • Two ice axe loops
  • Two rear pad/tent straps
  • Two straps to secure the ends of the roll top
  • Single top compression strap
  • Single Sternum strap
  • Two load lifter straps
  • Two shoulder straps
  • Two rear hip control straps
  • Two webbing straps on front of hip belt
  • 5 elastic cord pulls on the side water bottle pockets, open rear pocket, and two shoulder strap pockets

Let’s take a closer look at some of the functions that these webbing straps provide, because they are significantly different from what you find on other packs and provide a lot of extra versatility. However, there are so many straps on this pack, that I’m not going to cover all of them. If you have questions about them, please ask them in a comment below.

The Fusion 50 has two tiers of side compression straps. The bottom tier is anchor to a side seam, while the top tier is achored above the back pocket to help pull the load down towards the lumbar pad for better load control.
The Fusion 50 has two tiers of side compression straps. The bottom tier is anchored to a side seam, while the top tier is anchored above the back pocket to help pull the load down towards the lumbar pad for better load control.

Side Compression Straps

The Fusion 50 has two tiers of compression straps that let you pull the load closer to your back and make it easy to lash long items like packraft paddles or fishing rods to the side of the pack. The top tier is unique, because it starts in the middle of the pack’s back, over the rear shovel pocket, instead of along the side seam, letting you pull the top of the pack into the center spine for better load-to-hip transfer. Both side compression tiers are also angled at 45 degrees, rather than horizontal, again pulling the load down toward the rear of the hip belt in order to provide a more efficient carry.

External straps below the rear pocket let you attach bulky items like a foam pad or tent body to the back of the pack.
External straps below the rear pocket let you attach bulky items like a foam pad or tent body to the back of the pack.

Rear Pad/Tent Straps

The Fusion 50 also has a pair of external straps located below the rear pocket that can be used to carry foam pads, tent bags, or poles so you don’t have to use up internal storage. I use this feature all the time when hammocking because I like to insulate my back with a accordion-style, foam Z-lite pad in warm weather. You can also use it to carry a tent or tent poles quite easily, however the straps are too short to carry a very bulky foam sleeping like a Therm-a-Rest Ridgerest or a bear canister (although you might be able to jury rig something with webbing extension straps and extra clips, and yes, a Garcia bear canister fits inside the pack easily.)

The Fusion 50 hipbelt is extra wide to distribute the load onto your hips and doesn't slip, even if you have squarish (man) hips.
The Fusion 50 hip belt is extra wide to distribute the load onto your hips and won’t slip down, even if you have squarish (man) hips.

Backpack Frame and Suspension

While the Fusion 50 is loaded with features, the star of the show is the backpack’s adjustable length frame and hip belt suspension system. It consists of three components, a shoulder yoke, a hip belt, and what Six Moon Designs calls the “spine”, a vertical structure which channels the weight of your load to the hip belt.

The shoulder yoke can be raised or lowered to match your torso length. It slots in behind the spine where it’s held securely in place using velcro. Six Moon provides a small plastic tool that you can insert into the spine to release the velcro, which makes it easier to reposition the yoke’s height. They also sell shoulder straps with different shaped shoulder pads to accommodate both men and women.

Interior view of the plastic framesheet and aluminum stay that make the Fusion %22spine%22
Interior view of the plastic framesheet and aluminum stay that make the Fusion “spine’>

The spine is a rigid plastic sheet flared at the top that narrows as it approaches your waist. It is reinforced with a center aluminum frame stay that you bend to match the shape of your back. The frame stay gives the plastic panel extra rigidity and runs the length of the back, terminating inside a modest lumbar pad. The narrow shape of the spine (together with the side compression straps) keep the pack off the side of your back, significantly increasing ventilation and helping to keep your shirt drier.

The hip belt, which is available in multiple lengths, is held in place behind the lumbar pad and attached to the spine and pack bag with velcro that locks it in place. The rear wings of the hip belt are reinforced with plastic inserts to stiffen them and to prevent the hip belt from collapsing when the pack is loaded with weight. They form a remarkably rigid unit despite the fact that they are separate interlocking components (on this pack), quite comparable to integration you get when you sew a hip belt directly to the back of a pack. The benefit to users is the ability to swap in different sized hip belts, so you can get a better fit.

The hip belt runs behind the lumbar pad at the base of the center "spine".
The hip belt runs behind the lumbar pad at the base of the center “spine”. Note the dual straps on each side of the hip belt, which are designed to adjust to your hip shape and prevent the belt from slipping below your iliac crest (hip bone).

The wings of the hip belt are quite wide, a full 7 inches which help distribute the load around your hips for better comfort. The front of the hip belt has top and bottom straps that can be adjusted independently to match the curvature of your hips, for example if they flare out on the bottom. This helps prevent the hip belt from slipping below the knobby protrusion of your hip bone called the iliac crest, so that the load remains on your hips and is not transferred to your shoulders. It’s a phenomenal hip belt and doesn’t slip or loosen when worn.

The Fusion 50 also comes with two hip belt pockets, sized for storing a small camera, bug dope, or Aqua Mira bottles. These have durable solid fabric faces and close with zippers that provide very secure storage.

This combination of shoulder yoke, spine, and hip belt works remarkably well on the Fusion 50, providing a solid carry that feels like it a single unified frame even though its been assembled from separate components so it can be custom fit to your body’s dimensions. It’s an impressive piece of engineering, that gives the Fusion 50 the ability to carry much heavier loads than other ultralight style backpacks that weigh three pounds or less.

The Six Moon Designs Fusion 50 Backpack is a versitlie lightweight backpack that works with many different gear combinations ranging from bulkier hammocking or shoulder season loads to long multi-day trips when you need to carry extra food and water.....and everything in between!
The Six Moon Designs Fusion 50 Backpack is a versatile lightweight backpack that works with many gear combinations ranging from bulkier hammocking or shoulder season loads to long multi-day trips when you need to carry extra food and water…..and everything in between!


The Six Moon Designs Fusion 50 Backpack is a lightweight backpack (2 pounds 14 ounces) that is designed for long distance backpacking and multi-day backpacking trips capable of carrying over 40 pound loads. With an adjustable length frame, multiple length hip belt sizes, and female friendly shoulder pads available, you can really dial in a custom fit with the Fusion 50 without paying for a custom-made pack. While the Fusion 50 excels in carrying heavier loads, it also compresses quite well for simple overnights and technical day hikes.

If you’re looking for a new backpack and considering other lightweight packs in 50-65 liter range weighing 2-3 pounds, I’d encourage you to put the Six Moon Designs Fusion Packs on your short list. The Fusion frame and suspension system is so much more capable and comfortable than comparable packs that you’ll quickly see the logic of its unique design. Add in the ability to adjust the torso length and select a hip belt that fits your dimensions, and the rest will be history.


  • Adjustable torso length frame backpack with multiple hip belt lengths available for a custom fit. S-shaped shoulder pads are also available – good for women.
  • Wide 7″ hip belt with doesn’t slip, with dual, stacked webbing straps that provide a unisex fit
  • Excellent carrying capability for 30-45 pound loads; excellent frame stiffness and comfortable load transfer to hips
  • Pack compresses well for smaller loads
  • Load lifters are front angle adjustable; a high-end backpack feature


  • Cluttered with many compression and suspension webbing straps
  • Items can pop out of shoulder strap pockets and rear shovel pocket if you tip over far enough.

Disclosure: Philip Werner received a sample Fusion 50 backpack for review, but has no business relationship with Six Moon Designs.

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  1. FWIW, the load lifters on my Fusion broke on my first trip with it and the aluminum stay snapped on my last trip with it. Customer service leaves a bit to be desired, lost trips waiting for them to help me out. Love the functionality of the pack when it is functional, though.

    • How did you break a bendable aluminum stay? Curious. Being local, if you even need to borrow a pack, give me a shout. I’ve got a few extras you can borrow usually.

      • I have no idea how it broke. It snapped right at the top of the hip belt. Was setting up camp on a Friday night and the belt was just flopping around. Pulled the stay out at home after the trip and it was broken clean off. My only theory is there was some kind of repetitive bending back and forth motion while I’m hiking? At the time it broke i had probably 35lbs in it between my gear and the 6 tall boys for the weekend.

        Thanks for the pack offer, I’ll keep that in mind when I get strike 3 with this bad larry.

  2. I had the new model Fusion 65. I really liked about 95% of the pack. The two things I didn’t like were related to the fit of the pack on my body. First was the shoulder strap pockets – they were so ridiculously high on the straps they were useless to me. Second, the shoulder yoke rode so far out on my shoulders that the straps were over the joint between shoulders and arms and would not carry comfortably. This was true with both types of shoulder straps. SMD was very helpful while I tried to get this figured out. I did love the hip belt, both the dual levels and the pull-forward adjustment.

    • Good that you didn’t settle for a pack that didn’t fit. What did you end up using instead,

      • I have settled on a stable of three packs. 2015 Gorilla and 2015 Mariposa with a new 2016 hip belt modified to each, and a Seek Outside Unaweep 3900 for heavier loads. If I ever get the chance to hike in a place where a bear canister is required, I’ll see which of these will do the trick. (Who am kidding? I’ll be in a devoted search for a new pack!)

      • The Mariposa and Unaweep will work fine with a canister.

      • Out of curiosity, what is your torso length? I’m surprised that the shoulder straps were way to long for you. Also, what year did you try the Fusion? I take it there have been multiple models with improvements over the past two years. I tested the latest and greatest 2016 model.

        For the record, I think the Fusion hip belt rivals the ones on the Seek Outside Unaweep and Divide packs in terms of fit. The Fusion is much better in terms of features. I’m a big fan of hip belt pockets.

      • My torso length is 19.5″, but the problem wasn’t that the straps were too long. If anything, they were short, hence the pockets being so high. The real problem for me was that the yoke was too widely set. Hence the straps riding on the shoulder-arm joint rather than on the shoulders. This was with the 2015 new model of the Fusion 65 and both the regular and S-curve straps. As I told the guy who bought it from me, I guess I’m not as broad-shouldered as I thought I was. And therein lies the real problem. It’s not that the pack was defective or designed poorly. It, as many others I have tried, just didn’t fit me. Other packs do fit me. If I were able to have the yoke custom-built, I’d buy another Fusion. Maybe I’ll ask SMD to do that!

      • Thanks for clarifying. That makes perfect sense.

      • It really was the oddest thing. It took me forever to figure out what the problem was. I kept making “up and down” adjustments (torso height, load lifters) when the issue was “side to side”. I really, really liked that pack.

      • Turns out SMD can’t do custom yokes, and the guy to whom I sold the Fusion 65 can’t get it to fit him, either. I’ve got a pack headed back to me, now. Maybe I’ll try to figure out how to modify it myself.

      • Ron told me that they’re going to have many more yokes in the future in different sizes.

      • That’s good news. I’ll contact them with that information and ask them if they can put me on a notification list.

      • I finally got around to contacting SMD about a size Large yoke and received it this week. With a weekend-sized trip test load, it looks like this will work. I can get it adjusted so that the straps don’t sit so widely on my shoulders. I should be able to check it out on a trip in a few weekends.

      • Took me more than a few weekends, but this weekend I finally did try it out on an overnight along the Bartram Trail in northeast Georgia. I am happy to report that the large yoke worked.

  3. The sizing on these packs makes no sense. My friend who has a short torso (18 inches) and it only 5’5″ has to put the shoulder harness on the highest setting. You would have to be a midget to use anything less as we both have commented on when looking at him wearing the pack. Just looking at the pack it is ludicrous that anyone who is inner the upper torso range it supposedly fits (22 inches) could actually use this pack. The frame would not even make it packs your shoulders. That said if you are really short he says it is very comfortable and the favorite of all his packs he has ever used. Just don’t expect to use it if you are average torso/height or greater.

    • Sounds fishy. I have an 18.5″ torso (which is average and not short) and have adjusted the pack to fit me easily, raising the yoke about 1 position. Suggest you contact the mfg. for fitting assistance if you haven’t already returned the pack.

      • Looking at the first picture in the post, it looks like the top of the frame is pretty much at your shoulders. You can’t tell me that if your back was 3.5 inches longer (they say this will fit a 22 inch torso) that could possibly work for. Sorry, this SMD pack is once again another design failure of this type of adjustable pack, you can’t have one frame size and have it fit a 7 inch torso range as they claim by just moving where the shoulder traps attach.

      • But I still think an 18″ torso should be fine (which is what we were discussing.) Just saying.

    • I tried this pack and had fitting issues as well. I’m 5’8 w/ a ~ 20″ torso. I don’t recall exactly what the fitting issues were, but I recall the pack feeling short, even when adjusting the torso length. I too found the strap pockets to be located too high. I ended up with a Mariposa — love it. Though I try to keep max start weight to ~27lbs I’ve had the pack up to 33 lbs total weight without issue.

  4. I have had 2 of the 2014 model of this pack and love it! $100 price is great as well. As to the comment about sizing, unless the 2014 is drastically different, I am 6′ 1″ and have it set to the medium setting. I originally had it at the large but when I went in at Neel Gap we resized it and it carried better and was much more comfortable. I did notice the new version has what looks like 4 sizes instead of 3 on the 2014. The 2014 is also lighter at 36oz with the medium hip belt.

  5. Regarding the compression straps pulling the sides of the pack away from the back for better ventilation (an idea I like, as I hate a sweaty back), did you find that this pack rolls side-to-side more as a result? For example, when negotiating blowdowns, etc. is there increased lateral shift to the pack due to less contact with one’s back?

  6. The “spine” reminds me of the Exped Lightning external frame concept of imitating or taking advantage of the human anatomy to carry loads more efficiently on our backs. I thought they were really thinking outside the box on that one. Maybe this is the evolution of framed packs and we are going to see more designs like this in the near future?

  7. I like this pack a lot. I have the 2014 Fusion 65, which is closer to the current Fusion 50 volume. The price was right at $120. I love the adjustability – as a Scout leader I am often lending gear out and that helps a lot.

    Many of the issues with this design have been at least partially addressed in more recent iterations – larger shoulder, hip and side pockets, more volume overall, and improved (but could still be better) retention/security on the shovel pocket.

    I used this pack in Philmont with 35-50 pounds (food/water variance) and was happy. The shovel pocket is dinky, and in general outside pockets were small – I used a Gossamer Gear Hipster (fanny pack) for snacks and a Zpacks MultiPack as an “office” and had plenty of accessible storage. As noted, later versions have larger pockets. The shoulder strap pocket was good for an umbrella base.

    Lower loops (where you put the ZLite) worked well for a Tarptent Rainshadow 2. The 2014 version has hydration ports but no good way to hang hydration bags, will see if the new sleeve is available aftermarket. This is my primary pack right now.

    Six Moon Designs needs to put more effort into their website, in particular showing products from multiple angles. Pictures are cheap.

  8. Do you think the hip belt may be too wide for someone short? The hip belt on my ULA Circuit is something like 4.5″, which feels pretty substantial on my 5’2″ body.

    • I couldn’t say. Call them or order one and return it if it doesn’t fit you. That’s why these small guys have return policies. You’ll be interested to know that they guy who designed the Circuit is the same guy who co-designed this pack for Six Moons.

  9. Thanks! This pack is definitely intriguing. :-)

  10. Very timely as I’ve been contemplating what pack to use this weekend. We’re doing a 3-day, with the probability=0.9+ of no water anywhere, so my water load will probably be about 15 lbs at the trail head. I’ve got an old Osprey Atmos, but its “packability” is severely lacking: it’s very hard to get a bear can (gah!) and a tent in/on it at the same time. My Mariposa is totally unsuited to the weight (even with the 2016 belt upgrade), but can package everything just fine. Kinda too late now to get something newer and better suited to the task at hand, but at least I’ve got more things to consider…

    • Similar considerations for my next trip as well, when I plan to carry the Fusion. It can go heavy in comfort and good stability for some very dry and difficult sections of trail. No bear can but lots of gear, food, and water that simply blow out a Mariposa.

  11. Except for the complicated straps, this sounds like a good pack for youth. Adjustable torso length is a necessity, and the volume could help keep the weight down.

    I grew four inches while I was 13, so fixed-size packs are a bad choice for youth.

  12. I don’t have the Fusion but I do have the previous model of the Flight 30 and the current Flex Pack so my comments have some relevance for anyone considering buying a pack from SixMoon. First their customer relations is poor and in particular with the flight 30 even though I ordered direct and so they had my email details they never contacted me over the serious issue that they had with the plastic stiffening wires on the straps – instead I suffered numerous cuts until I dug the wires out with a knife and pliers. Second the Flex Pack arrived without any instructions which given how complicated & the numerous possible adjustment is a serious omission. So far I have been unable to get the Flex to fit comfortably but otherwise it meets my requirements for carrying a heavy load including a packraft and (importantly) as I live in the tropics like the Fusion having good gap for air on the back.

  13. For me it came down to the SMD 65 and the Exped Lightning 60. Very similar in my opinion. Lightweight Packs that put the load on your hips and can carry extra weight when necessary. What I Like is the ventilation, the pack is well away from my body. Found the Exped for less than $200 when the SMD was over $250. Don’t know where you are finding it for $100. The Exped has even less external storage which I think is the one drawback.

  14. I ended up carrying 36 lbs the first day, which was pretty short (~5 miles), but pretty steep (~3000′ up), and had no problems with my hybrid Mariposa (2014 body + 2016 upgraded belt). I distributed my water load around in 1 liter bottles, so it wasn’t one large lump and that might have helped.

    That being said, I’m still going to see if I can try out one of these SMDs as my “guide pack.” As always, thanks for the great write-ups.

  15. I have the 2014 Fusion 50 and love it, but I can’t seem to get my winter setup in it and I end up reverting back to my Trekker 65, I’ve been considering the new Fusion 65 but not sure its worth spending the money to save 1.8lbs off the trekker

    • 1.8 pounds is a pretty big weight drop for winter hiking and might be worth it. You’ll quickly feel the weight difference if you’re climbing a mountain wearing crampons or snowshoes. I’ve spent a lot more money to shave a lot less weight off my winter backpacking gear list.

  16. Hi,
    They list the weight 36 oz on their website, but you say it is 2.14; is this a typo or you weigh it differently?
    I have been seriously thinking to buy one, since they dropped the old version for international purchases to $110, but rwading all this feedback, I’m more inclined to get an Exos 48, since it is tried by more people and I’m not living in the US to deal with Six Moon’s CS to iron out the fit problems (I have a 20″ torso).

  17. Having used this pack for several years now I feel we’ve done enough miles together to comment.

    The essentials for a good pack are good sizing on you so it fits properly and good compression so that the load doesn’t move about as you move, and can reduce the pack volume to still retain that good control throughout your trek.

    The frame and hipbelt provide a really solid foundation, the shape of the bag itself, plus the compression system that goes from the spine all the way round the pack tick those boxes better than any other pack I’ve seen.

    On the first version of the pack there was an issue over sizing, and the stretch mesh side pockets are vulnerable to branches.

    My original version fusion 65 has more like a 40-45 litre main pack volume that is good for 3 season trips of about 5 days. The newer 65 is larger and will do longer trips. However the compression is so good that it will do overnighters equally well.

    As Phil notes, the round shape of the bag also means excellent ventilation.

    Imho, this is a great pack that suffered in its reputation because of the mis-sizing problems with the first packs.

    For real world lightweight backpackers wanting a solid pack that does the basics as well if not better than anything else, I couldn’t think of a better pack to recommend.

    And remember, that’s a recommendation made after several years use, unlike most reviews you will see on the net.

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