The Six Moons Designs Fusion 50 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.
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.
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 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 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.
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.
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 the front of hipbelt
- 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.
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.
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 an 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 bear canister fits inside the pack easily.)
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 that 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.
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 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 it’s 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.
|Make / Model||Weight (oz)||Type|
|Gossamer Gear Mariposa 60||30.5||Speed flap|
|Granite Gear Crown 3 - 60L||36.7||Roll top, Top lid|
|Granite Gear Blaze 60||48||Roll top, Top lid|
|Hyperlite Mountain Gear Southwest 55||32||Roll top|
|Osprey Exos 58||43||Top lid, speed flap|
|Gregory Focal 58||41||Top lid, speed flap|
|Zpacks Arc Blast 55||21||Roll top|
|Mountain Laurel Designs Exodus 57||18||Roll top|
|Mountainsmith Scream 55||45||Roll top|
|Seek Outside Gila 3500 (57L)||47||Roll top, side zipper|
|Sierra Designs Flex Capacitor||41.2||Top lid|
|Elemental Horizons Kalais||37||Roll top|
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 shortlist. The Fusion frame and suspension system are 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: The author received a sample 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.