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KS Ultralight Gear Alpisack Backpack Review

The KS Ultralight Alpisack is configured like a climbing backpack with an optional top lid

The KS Ultralight Alpisack is a 50L frameless backpack weighing 21 oz. While it can be used year-round, it has a few special features that also make it suitable for climbing, snowshoeing, skiing, and winter hiking. Being frameless, it can’t carry much more than 20-25 pounds of gear, water, food, and fuel, but if you can limit the amount of heavy traction (snowshoes, crampons) and climbing gear you need to carry, it’s quite a comfortable and functional climbing and winter hiking backpack.

KS Ultralight Gear is a Japanese cottage backpack maker that sells a wide range of frameless ultralight backpacks. Owned by Laurent Barikosky, you can order a wide range of customizations for each one of their packs. What sets KS Ultralight apart from other cottage manufacturers is the breath of pack fabrics they offer, including XPac, DCF (cuben fiber), Dyneema Gridstop, and Cordura. They’re also much more willing to customize a backpack for you than most US-based ultralight cottage backpack manufacturers and it’s still a core part of their business.

Ordering a heavily customized backpack is not for the faint-hearted, because you’ll be stuck with it if it doesn’t work out as well as you’d hoped. In order to avert disappointment, I’d suggest that you use a frameless ultralight backpack for a while to learn what you like and don’t like, before rushing out and having a heavily customized one made for you.

Specs at a Glance

  • Volume: 50L
  •  Weight
    • Backpack including hip belt in sewn-in back panel padding – 18.5 oz
    • Optional Top lid w/ 1L pocket – 2.5 oz
    • Optional Accessory hip belt pocket (1) – 1.1 oz
  • Materials:
    • 210d Dyneema Gridstop body
    • 500d Cordura base
    • Spacer mesh on hip belt and shoulder straps
  • Sizing:
    • Torso length: 53 cm (fits 18″-21″)
    • Hip belt length: 95 cm (fits 32-38″)

Backpack Organization and Storage

The Alpisack has a 1L top lid pocket, a large main compartment (no hydration reservoir or ports) that closes with a drawstring, and two side water bottle pockets. The demo pack I received came with one large removable hip belt accessory pocket, also made with 210d Dyneema Gridstop. Both hip belt straps have daisy chains sewn to their outside so you can rack carabiners and other gear to them, which is the norm on many winter packs.

The Alpisack without the optional top lid, packed at maximum capacity.
The Alpisack without the optional top lid, packed at maximum capacity.

The top pocket is floating, so you can wedge gear under it if it’s bulky, like a rope, or it overflows the main compartment. Like most top lids, it sags awkwardly and off-center if you overstuff it. While having a top lid can be convenient in winter for storing gloves and food, I quickly decided I preferred carrying it lidless. If I were to order a custom version for myself, I’d probably opt for a roll-top with the top strap, shown above.

The side water bottle pockets on the Alpisack are made with 500d Cordura and have elastic sewn into the top to help keep your water bottles from falling out. However, the pockets aren’t really tall enough to hold Smartwater bottles very securely or wide enough to hold an insulated 1L bottle for winter hiking. This is another area that you may want to customize a bit.

The side water bottle pockets aren't really tall enough to hold a SmartWater bottle unless you lash it in with the bottom compression strap
The side water bottle pockets aren’t really tall enough to hold a Smartwater bottle unless you lash it in with the bottom compression strap.

External Attachment System and Compression

The heart of any alpine or climbing style pack is its external attachment system and the Alpisack does not disappoint. The pack has two tiers of compression straps, two ice ax loops and two ice ax shaft or trekking pole holders made with elastic cord & cordlock. If you want to secure a  foam sleeping pad underneath the pack bottom, there are another two elastic cords (removable) provided for this purpose.

A daisy chain runs down the center of the back panel, which can be used to lash gear to the back of the pack, like microspikes with a carabiner. You can also run cords w/cordlocks in a criss-cross pattern or horizontally across the back, threaded into the webbing loops that hold the rear compression straps to the pack. I’ve slipped a carabiner through one of these loops to hang a pair of microspikes in the second photo above, to show you where it is.

In addition to the daisy chains on the hip belt, the Alpisack also comes with daisy chains sewn to the shoulder straps. This is a feature I use year-round to hang navigation and electronics gear from. I have a hard time using backpacks without them.

The Alpisack comes with a padded backpanel but it doesn't provide any structural value or stiffness
The Alpisack comes with a padded back panel but it doesn’t provide any structural value or stiffness.

Backpack Frame and Suspension System

The Alpisack is a frameless backpack, but that doesn’t mean you can’t add some rigidity to the pack yourself. While there is some padding in the panel behind the shoulder straps, it’s very soft and doesn’t do much except prevent packed items from poking you in the back. When I pack the Alpisack, I place a cut-down 8 panel Therm-a-Rest Zlite pad behind the padding inside the main compartment. Then I pack the pack as I normally would with my quilt/sleeping bag loose at the bottom, filling the main compartment as tightly as possible, using the side compression straps to shrink the volume if necessary. This helps stiffen the back of the pack like a real framesheet and improves the carry. I think the pack would benefit even more if it had an internal sleeping pad pocket, since it would act more like a real framesheet and not deform as much under pressure. But that’s a customization you can ask for.

The hip belt is lightly padded and sewn to the base of the pack but again, it’s not really designed to provide much load transfer. This is a frameless pack with a max load of 20-25 pounds, which you can probably carry that on your shoulders without too much discomfort. It does provide a good hip wrap because it’s fairly soft, but the hip belt “wing-span” (the padded area) is a little on the short side. When ordering, I’d suggest specifying the exact length of the padded wings you need for your hips.

The KS Ultralight Gear Alpisack is a comfortable and well appointed frameless winter and climbing backpack
The KS Ultralight Gear Alpisack is a comfortable and well-appointed frameless winter and climbing backpack.


The KS Ultralight Gear Alpisack is 50 liter frameless backpack that weighs just over a pound. It’s very easy to use and super comfortable to carry, the quality of the sewing is excellent, the materials used are durable and high quality, and the fittings are all well executed. However, with a max load limit of 20-25 pounds , you have to ask yourself if you can get your skin-out weight (gear, food, fuel, and water) low enough for winter backpacking or whether the Alpisack is better suited for snowshoeing, skiing, or climbing day trips when you can get by with less gear and supplies. While the Alpisack is outfitted with winter conditions in mind, it’s also well suited for year-round use, particularly if you need to hike or backpack through areas that experience winter conditions in autumn or into spring.

KS Ultralight Gear Alpisack Backpack



The KS Ultralight Gear Alpisack is 50 liter frameless backpack that weighs just over a pound and has a max recommended load limit of 20-25 pounds. While optimized for winter, it's also well-suited for year-round use across a wide range of climates.

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Suggested Customizations

Here are the customizations I’d recommend when ordering a custom-built Alpisack.

  1. Remove the back padding that comes with the pack. Replace it with an internal sleeping pad pocket-sized for an 8 panel Therm-a-Rest Zlite foam sleeping pad. It’s got to be a pocket with a velcro lid flap and not a sleeve. This will help stiffen the pack and increase the amount of weight it can carry.
  2. Replace the top drawstring and top lid with a roll top closure.
  3. Make the side water bottle pockets taller and larger, with a slanted opening. As is, Smartwater bottles are a bit too tall to be held securely, while the pockets are a bit too small to hold a Hunersdorf bottle insulated with a neoprene cover.
  4. Replace the center back daisy chain, and shaft holders with two daisy chains running down the back panel to the ice axe loops. They can be sewn with very narrow webbing to save weight and would look cool. You could even add a crampon patch between them.

Disclosure: The manufacturer provided the author with a sample backpack for this review.

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  1. I’m happy to see you review this pack, Philip.

    I’m still not sure what to choose between the Cold Cold World Chernobyl and the KS Alpisack. The level of customisation of KS is greater than CCW and it’s easier to communicate with Laurent for me. But, CCW does great bags too.

    How would you compare both of them ?

    • The Chernobyl is 2 pounds heavier…
      But if that doesn’t matter to you, I’d go with the Chernobyl. It’s a far more developed and proven mountaineering backpack.
      The Alpisack is nice too, but it’s strength is in milder weather. I plan to use it as a frameless pack next year for section hiking the NH AT starting in mid-April.

  2. I missed the review so this is a late post. I do not see many reviews of KS-Ultralight’s products.

    I would love it if you had the opportunity to review KS-Ultralight’s Waist Pocket. I use a waist pack for most of my day hikes. I am currently using an Osprey Talon Six. The offering from KS-Ultralight is 2-3 ounces lighter and seems well made. Thanks.

  3. Hi Philip. I’m somewhat confused in your comparison to the CCW Chernobyl. You mention the CCW is frameless and can carry 35lbs comfortable. You mention the KS is frameless and can only cary 25lbs comfortably. What makes the the carrying capacity of the CCW so far superior? I don’t think it is. They are both framless. Furthermore, the KS could come with removevale frame carbon frame stays that could more demonstrably increase load carrying capacity beyond knowing how to pack a backpack correctly. You tip preference to the CCW pack even though it’s 32oz heavier. How could that be? The Dyneema fabric of the KS is just as proven in the realm of alpine durability. I agree the CCW is a great pack but I the materials (not the design) put it’s weight out of date.

    • There’s a major difference between the two “frameless” packs. Reading my comments, I think I was referring to the CCW Choas and not the Chernobyl, but the validity of my comment still stands. Both the Chaos and the Chernobyl have an internal pocket that holds a foam framesheet which the KS doesn’t. When the Chaos/Chernobyl is packed tight that foam sheet becomes fairly rigid and acts more like a frame than a loose zlite rolled up inside the the KS. That’s why .I suggest having an internal frame sheet pocket added to the KS pack. CCW packs are also by default made out of a much heavier weight material that has very little stretch in it, compared to the KS. That’s the apples to apples comparison. The Dyneema Grid fabric you’re referring to in the KS pack is nylon with some dyneema threads running through it (yes, total marketing bullshit). That’s very different than an all Dyneema backpack or even a Dyneema DCF backpack.

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