The Mountainsmith Zark 40 is a multi-purpose backpack with vest-style shoulder straps that can be used for backpacking, hiking, or traveling. Newly updated, the Jerk 40 (34 oz) features a roll-top closure, a new zippered front map pocket, a removable hip belt strap, and a removable foam framesheet. External mesh pockets are more durable than before; External attachment options are more flexible, and expand the new Pocket Pack’s already considerable external storage. If you like to carry a lot of gear on the outside of your pack for easy access, the Zerq 40 is worth taking a close look at.
Finally, the range of packs and accessories under the “Zerk” moniker has expanded: there is now an optional Zerk 7 L top lid compatible with all Zerks, a higher-capacity Zerk 55 model, a new Zerk UL 20 daypack, which replaces the Zerk 25 (which is my favorite daypack), a Zerk 13 daypack w/ a 2 L hydration system, and the Zerk 3 lumbar pack.
- Weight: 34 ounces
- Volume: 40L
- Type: Frameless
- Access: Top (roll-top)
- Gender:Unisex
- Hydration Compatible: Yes, Central Hose Port Internal Hang Loop
- Pockets: 12 (11 open, 1 closed)
- Torso Range: 16-21″
- Bear Canister Compatibility: BV500 and BV475 fit inside vertically
- Materials: 210-denier Robic Nylon X-Grid with Extrema (UHMWPE) R/S UTS; 100-denier Robic Nylon Extrema (UHMWPE) R/S UTS; 150-denier high-density polyester liner; YKK zipper; Eva foam
- Maximum recommended load: 20-25 pounds (manufacturer claims 30 pounds)
Backpack Frame and Suspension
The Mountainsmith Zark 40 is a frameless, fixed-length backpack with wide, vest-style shoulder straps and a removable webbing hipbelt. Although it has a soft foam back panel, the lack of a load-bearing hip belt means all the weight of your pack will rest on your shoulders.
If you’ve never owned a backpack with vest-style shoulder straps, it may take some time to get used to them as they offer a very different feel than more traditional backpack straps. For one, vest-style straps lie flat on your shoulders and upper chest and don’t actually curve around the curves of your torso like traditional backpack straps. Depending on the pack, you may find them too short or too far apart, which can also affect comfort. I like the shoulder straps on the Jerk 40 because I find they cater to those with a wide chest (size 46), whereas many running packs I find cater to people with a narrow torso. In fact, I find many running-style vests and trail running packs useless for this very reason.
While the Zark’s shoulder straps aren’t heavily padded, they aren’t too thin either. They are 3″ wide at the top and sewn directly to the top of the pack-bag, widening to 4.5″ at the bottom, with dual sliding sternum straps between them. Each shoulder strap has two mesh front pockets and gear loops on the sides, so you can secure items like the inReach to keep them from getting lost even if they fall out of the pocket.
Zark’s hipbelt is a webbing strap and is not weight bearing. This is provided to help keep the pack close to your hips so it doesn’t bounce around, but it can also be removed. The hip belt is attached to the pack with a Gatekeeper clip that you can unscrew and remove. You will need a pair of pliers to apply enough pressure to the buckle to open the gate, which is too strong to open by hand.
The Zark has a foam pad in the pad pocket on the back of the shoulder straps; Its primary purpose is to protect your back from being pinched by the contents of the pack and it is not structural like a proper frame. It’s also very soft, and won’t keep the pack bag from digging into your back if you overstuff it. The foam backpanel on this latest Zark 40 is slightly different from the previous model and weighs slightly less. You can remove the pad or replace it if you really want (it weighs 2.9 ounces), but I’d still recommend using some sort of insert in its place as it gives the pack a shape to the bag, making it easier to pack.
Backpack Organization and Storage
The Zark 40 is laid out like a typical ultralight pack with a roll-top, front mesh pocket, and side pockets. The roll top can be clipped to the top by itself or attached with a clip on the side of the pack, which is my preference as it provides better compression. There is no strainer of any kind on the top of the roll top, so you’ll want to make sure you roll it a few times to keep it from unraveling (even then it will unravel). The lack of this stiffener is a negative as it makes it difficult to pack the pack unless it tears rapidly. This model also features a new Y-strap to secure gear like a foam pad on the top of the pack.
The Zerq 40 is designed with plenty of external pocket storage so you’ll have everything you need for the day within easy reach without needing to stop to look for something in the main compartment of your pack. While this packing philosophy is no different from any other lightweight or cottage-built thru-hiking backpack, the location of the Zark’s external pockets and the degree of organization they provide set them apart from hipbelt pockets on more traditional backpacks. Everything you need from snacks, gel packs, water bottles, bug dope, sunscreen, maps, smartphones, and more can be stored within easy reach in the shoulder strap pockets or Zark’s advanced side water bottle pockets.
The Zark 40 has three side pockets on each side: two upper mesh pockets and then four lower pockets, two on each side, which overlap. The upper pockets are the size of a one liter cook pot. The very bottom pocket can be used to store a water bottle, while covering it is a second pocket, which I liken to “hamster cheeks.” These are good for storing extra snacks, fruit, or even trash wrappers so you don’t have to close and open your pack to access/put them away. I prefer these “hamster cheek” pockets to the mesh pockets that many ultralight backpack manufacturers have started placing on the base of their backpacks. The latter makes no sense from a durability perspective. When you place a pack on the ground, the most friction occurs at the bottom.
There is one downside to the upper pockets, which are new to this pack: They interfere with the contents of the lowest pocket if you try to put a one-liter soda or SmartWater bottle in it because they’re so low. So if you’re going to use water bottles with the Zerq 40, use small bottles, a hydration bladder, or small 500ml bottles in the pocket of the waist shoulder strap.
On the front of the pack, there’s also a new map pocket above the front mesh pocket, which is useful for storing maps and personal items you want to keep track of.
The rest of the Zark 40 is pretty conventional. The pack is hydration-compliant, with a center hose port between the shoulder straps, hose keeper loops on both shoulder pads, and a hook inside to hang your bladder, plus a new hydration pocket.
The front mesh pocket is large and ideal for carrying wet or loose items like rain gear, water filters, or an ultralight tent, and it’s made with the same heavy-duty mesh used on the side water bottle pockets. It’s surrounded by black daisy chains so you can run an external elastic cord over it or add additional items to the exterior of the pack.
Compression and external attachment points
The Jerk 40 has side compression straps that you’ll want to use to get the load as close to your center of gravity as possible, especially if you’re carrying a heavy food load. The straps can be moved to different anchor points on daisy chains that run up and down the pack. If you prefer to have hack backpack attachment points, this pack is for you. The flexibility is almost overwhelming.
There’s a new Y-strap that loops over the roll-top to provide top-down compression, which can also be used to secure the foam pad on top of the pack. There is also an ice ax loop, although no shaft holder is provided. If you need one, simply roll your own with an elastic cord and a cord lock.
If you need to carry the Bear Canister, you’ll want to store it vertically in the Zark’s main compartment. The Zark doesn’t have much body, even when fully packed, so trying to tuck it under the Y-strap doesn’t work so well.
Comparable vest-style hiking packs
recommendation
The Mountainsmith Zark 40 is a multi-purpose backpack with a waist-style shoulder harness and non-load-bearing hip belt. While it’s large enough for ultralight backpacking, it can be used in many different ways from peakbagging to commuting or traveling without breaking a stride. Weighing in at 34 ounces, the Zark is a surprisingly comfortable backpack, provided you don’t overload it carrying more than 20-25 pounds. Granted, it takes some time to get the hang of carrying a backpack without a load-bearing hip belt or rigid frame, but the Zurq’s shoulder strap and side pockets provide a level of organization and accessibility that’s not available on many other packs.
Disclosure: Author purchased this backpack.
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