ZPacks Arc Blast 60L Backpack

Hiked It. Liked It.

The Arc Blast is an ultralight backpack featuring Cuben Fiber construction as well as a tensionable, arc-shaped carbon fiber frame manufactured by ZPacks, a smaller gear manufacturer located in Florida. ZPacks have been steadily growing in reputation and popularity among lightweight backpackers due to their line of shelters, sleeping bags/quilts, clothing, and of course backpacks. I have been hiking with their Arc Blast for a little over a year now and these are my thoughts about it.

Specs at a Glance

All specs as claimed unless *noted otherwise…

  • Volume: 60 L (~47 L in the main compartment)
  • Weight: 17 oz
  • Max Load: 30 lbs
  • Fits torso: 18-24″ depending on size
  • Pockets: (3) 2 side, 1 front
  • Frame: External, carbon fiber
  • Closure: Roll-top
  • Primary Material: 2.92 oz Cuben Fiber Hybrid
  • MSRP: $295 (add-on’s available for additional $)
An Arc Blast, Jacob D, and a Tree
An Arc Blast, Jacob D, and a Tree

Impressions

Having previously owned several ultralight backpacks of either the frameless or semi-rigid frame (read: some sort of minimal stays) style I was pretty accustomed as to what to expect from the carrying capacity and comfort of such packs, and I figured the Arc Blast would be predictable in that regard. After loading it up I decided that it did feel pretty similar in those regards. Compared to frameless packs it’s a huge improvement in comfort and carrying capacity. Compared with packs I’ve owned that utilize a semi-rigid frame (most recently Gossamer Gear’s Gorilla) it was more of an incremental upgrade, mostly due to the superior frame design that ZPacks uses. Notably though the Arc Blast is substantially lighter than other “similar” packs, which is what really sets it apart in the market; it’s amazing that a pack weighing so little can carry so well.

Emphasis on the Arc
Emphasis on the Arc

The “arc”, which is the namesake of the pack, is created by pressing downward on the upper horizontal frame member to create a bend in the vertical frame members, then snugging up the line tensioner on the guylines (which connect between the mesh back panel and the frame). Once this is done the arc stays in place. It’s a very simple process and can be made more or less bowed to personal preference.

Frame Tensioner
Frame Tensioner

The Cuben Fiber of the pack is a more durable variation of Cuben than you’d see on a ZPacks shelter. It’s heavier too but add’s a measure of water resistance to the pack and of course it won’t absorb water becoming heavier as it’s worn in the rain. There is quite a bit of stitching though, and several seams, which left me curious how accurate the claim of “highly water resistant” would hold up. Speaking of stitching… after seeing a friend’s Arc Blast with the standard light grey back panel and inner hipbelt, I asked ZPacks if they could use black for those areas, which they agreed to – and it made a world of difference as far as appearance goes. All of the stitching is black so it blends in with the black fabric instead of contrasting against light grey. It seems that there are now several color options with black accents which is a good thing; those weren’t choices when I purchased mine.

Back View
Back View
Front View
Front View

The closure of the pack is similar to a dry bag. This is fine when it can be folded down a few times, but when the pack is full it can be tough to get it closed tightly. The seal is made with velcro and doesn’t have a backing strip nor is any of it rubberized, so it’s not really a dry bag seal and it shouldn’t be assumed to be watertight. To be fair, it may be like many ultralight dry-bags on the market, which is to say water resistant for the average user, but not something you’d depend on for hiking in extended periods of rain, stream crossings, or for use on a paddling trip.

The rear pocket is nice and roomy and the side pockets don’t require too much contortion to get to. As far as the volume goes, it’s always important to understand how a manufacturer measures this and ZPacks is very clear about how they do it. The main body of the pack is more like 45 liters (47 liters claimed) which leaves enough head space to fold the top of the pack down. The front pocket is a claimed 8 liters (this feels a little over-stated) and the side pockets amount to a claimed 5 liters total (seems about right). For someone who is carrying lightweight or ultralight gear this pack should provide plenty of space for extended weekend trips up to a week or so depending on how much food and water needs to be carried. Most bear canisters will need to be carried upright (BV450, etc…) inside the pack, smaller canisters may be able to pack horizontal.

I opted to get a few of the extras. Loops for trekking poles, ice axe loops, and the lumbar pad. The lumbar pad is a must for me. It adds comfort and gets the pack just a little further from my back (to aid with ventilation). As far as the extra loops go, they’re all very minimalist and could just as easily be added after the fact using extra cord and parts that most of us probably have in our gear closets, if not go ahead and order them and ZPacks will attach them for you.

Ice Axe Loop
Ice Axe Loop
Lumbar Pad
Lumbar Pad

After hauling the Arc Blast all over on trips I concluded that 20 lbs (or less) total weight is the sweet spot for me. At 25 lbs I can feel it on my shoulders a bit. With 30 lbs or more it’s getting into uncomfortable territory. This is always a subjective thing so take it with a grain of salt. To draw a comparison, I feel that it can easily go 5 lbs heavier than my Gorilla without any perceived increase in load. This is mainly due to the design of the frame, which works wonderfully. As far as keeping the pack away from my back, it does to an extent. If the pack is stuffed it’s going to contact my back, but when not trying to push the limits of it’s volume capacity, contact with my back is minimal to none, which is nice… no sweaty back! The pack did prove to only be somewhat (mostly) waterproof. It’s hard to determine points of water ingress, but the pocket stitching appears to be one of them. It took several hours of extended rain to amount to any substantial amount of water getting in.

Arc Blast Overloaded for Multi-Day Snowshoeing!
Arc Blast Overloaded for Multi-Day Snowshoeing!
Two of a Kind. ZPacks Multipack as lid at right.
Two of a Kind. ZPacks Multipack as lid at right.

As for durability, mine has held up well so far in what I would consider typical use for most people. The Cuben has held its own against brush and scrapes with rocks. Some of the stitching looks a bit strained, but nothing has failed or started to come apart. Two friends who were on the PCT last year reported seeing a number of Arc Blasts on the trail, and the report I got is that toward the end of the hike they were still going, but looking a little beat up. Both of those friends started with their own Arc Blast and one swapped packs at some point, the other carried his for 2000 miles before having to leave the trail. Both of their packs are still in good shape. Joe Valesko (owner of ZPacks) has taken his on multiple thru hikes. These packs are not built to last forever, but the proof of their durability is out there. For some people 2000+ miles is one hike, for others it’s years worth of mileage. Factoring in that they weigh only a hair over 1 pound I think “only” getting a couple thousand miles out of one of these is a very decent deal, and getting more than that is a nice bonus.

Liked…

  • Excellent frame design
  • Very light for its class
  • Durable materials

Not So Much…

  • The velcro top is not a favorite of mine. I would almost prefer a cinch closure even though it would be less water resistant.
  • Lack of means to secure a bear canister externally.

Updates…

The Arc Blast has received at least one important change worth mentioning; for folks in the “taller” or “tallest” torso lengths, the frame of the pack is now extended so the harness always attaches below the top of the frame. This can make a substantial difference in comfort. Also worth noting is the availability of the Arc Zip, a panel-loading Arc Blast. Lastly, anyone in the market for an Arc Blast may want to check out the Arc Haul, which could be looked at as a beefed up Arc Blast. The harness and hipbelt integrate into the frame in a way that allows better load transfer, the pack comes with load lifters standard, a more padded harness, a more adjustable hipbelt, and Dyneema X fabric to improve durability. All of this comes at the cost of 7 ounces gained… but from early user feedback it seems to be worth the tradeoff… or at least worth considering!

Famous Last Words

The Arc Blast has been one of the most popular ultralight backpacks on the market since its introduction, and for good reason. The ability to carry 20-25 lbs comfortably while the pack itself is only a pound or so is impressive. The volume doesn’t facilitate use with a bear can, nor is it convenient for winter trips where bulk can be an issue, but it’s a great size/weight ratio for the hiker who is already carrying a conforming lightweight/ultralight kit and heading out for more typical 3-season jaunts. That arc frame is really hard to beat! Hike It. Like It.

Jacob D Written by:

Jacob is the head honcho, wearer of many hats, and modern day berserker here at Hike It. Like It. When he's not out hiking or running the trails you'll find him operating in full capacity as a Super Dad and chipping away at a degree in Kinesiology. This guy likes to stay busy. Follow on Strava

12 Comments

  1. Johnny casady
    October 31, 2017
    Reply

    I have used the arc blast for the last 8 months on the AT and the FT and been in a lot of bad weather the last 2 trips on the AT 2 5 day hikes I was in rain 80 percent of the time one day I was on top of a mountain with 40 mile an hour wind gusts side way hard rain for 2 hrs when I stopped for the night I checked my pack and no water was inside. Awesome best investment I ever made totally happy. Smoke and Jess

    • November 1, 2017
      Reply

      Awesome! Glad it’s working out for you! I need to take mine out more often.

  2. Paul S
    March 30, 2015
    Reply

    Thanks for all the great writing. I just wanted to comment about bear cans. I use the 60L as my primary pack for all but winter trips. I’ve put both a Bearvault 500 and a Bearikade Weekender in it w/o problems. Yes, its vertical, but I don’t feel I really lose any space. I pack around it, for example, my TR neoair xlite on 1 side and clothing on the other. I do find w/ a bear can that a sit pad or GG thinlite pad is nice extra cushioning on the side facing your back is nice for comfort.

    • March 31, 2015
      Reply

      Hi Paul. Thanks for the comments about your experience with your Arc Blast and bear canisters. Carrying them upright is cool. Some people prefer to carry them horizontally and others don’t seem to care as long as they can fit it one way or the other. I usually prefer horizontally but I’m adaptable 🙂 Wrapping the bear can in a thinlite pad is a good tip!

      • March 31, 2015
        Reply

        Just wanted to chip in regarding the bear canister – I was also putting it in vertically (of course), but it kinda rubbed off on the horizontal middle frame stay, and created a hole along it.
        After I shipped the canister away, I used some tenacious tape on both sides of this long tear, and it held well all the way to Canada.

        • March 31, 2015
          Reply

          Hey Noam. Thanks again for the info. I wonder if wrapping the bear can with a thinlite (or similar) pad as Paul mentioned would have eliminated the hole caused by rubbing on the frame?

  3. Andy Jarman
    March 12, 2015
    Reply

    I’ve had an Arc Blast for a bit over four years.

    I use my Arc Blast for canyoning. With a lightweight sea to summit dry bag as a pack liner I use the string on my compass to tow the rucksack behind me when swimming, with the string looped over my shoulder and the pack bobbing along behind me. Perhaps half a cup of water gets into the pack after a very long swim. I use the pack to protect the dry bag inside from damage.

    After four or five years of pretty rugged use I have noticed the following.

    The repeated stuffing/compressing of gear into the bag has lead to a degree of de-lamination of the fabric inside the bag. Whispey white hairs began appearing in the velcro at the opening, and looking carefully inside I noticed there was a translucent film parting company from the inner surface of the bag. I have bought some stick on patches from Joe and these seem to have repaired it nicely.

    Secondly I have inflicted a few nicks in the outside surface of the bag where it’s been dragged over rocks and wedged through holes.

    I’ve recently noticed there Zpacks offer an optional dynema fabric for an extra 50grams of weight that gives a tougher more abrasion resistant outer surface to the bag. I’m thinking this is probably worth getting for my type of activity.

    When it comes to the stitching – have no fear I regularly carry in excess of 13kg (28lb) (plus canyon water!) in my old bag and nothing is pulling, or giving the slightest hint of anything going wrong.

    I have the 52 Litre original version with only one cross member on the frame. I can now get three or four days food in the bag.

    I have bought the shoulder pouches Joe makes. I put a 0.75L (25 oz) flip top disposable water bottle in each. When I need the extra water I also put a tall 2L (67oz) disposable bottle in each outside side pocket.

    The water in the shoulder pouches is easy to get to without stopping and counter balances the weight of the pack for a more upright stance.

    At first the bottles kept falling out of the pouches. This is avoided by tying a loop of string to the pack straps at the top of each pouch and loosely dropping it over the top of the bottle.

    I like the fact that getting everything to fit in the bag is a test of your own commitment to lightweight backpacking.

    Joe has offered to make the netting on the front of the pack solid (he had to fix a ripped net once – $15, hah!) but I told him no thanks – the netting is purely for drying things in and for temporary stowage. The day it starts to become a proper storage place is the day my base weight starts increasing instead of decreasing.

    For trail hiking the Cuban Fibre Arc Blast 52L is the ultimate lightweight comfortable bag. If you tend to throw your gear off ledges and squeeze through gaps in rocks, crawl on your hands and knees through thick undergrowth and fallen trees you will get more miles out of the dyneema grid stop fabric version they offer – if you can stand the extra 50gram (1.75 oz) weight penalty.

    Fives years, and she’s looking a bit battered but a long way from finished.

    • March 13, 2015
      Reply

      Hey Andy.

      Thanks for all of the excellent feedback. That’s rough treatment, even for the heavier Cuben, yet it sounds like yours’ has held up pretty well! I’m familiar with the white wispy threads you described… those are the spectra threads inside the material that start to appear when it wears through or begins to delam. Surprisingly the stuff can still hold together pretty well even after this starts to happen, but obviously it needs to be addressed with either repair or replacement before complete failure happens.

      Thanks for reminding me that ZPacks recently started offering Dyneema. For your use it might be a good call! Then again, it’s gonna soak up some water so your pack is going to be wet after a swim. Tough choice. If it was me, and the pack had held up as well as you say, I would probably stick with the Cuben. The Dyneema would probably last a lifetime though…

  4. March 12, 2015
    Reply

    I carried that backpack on my 2014 PCT thru hike, and really enjoyed it. Only minor wear and tear, and the pack itself held beautifully. I highly recommend it.

    • March 13, 2015
      Reply

      Hi Noam Gal 🙂
      That’s awesome to hear! Congrats on your PCT thru hike, and thanks for taking time to comment.

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