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ZPacks.com Arc Blast Ultralight Backpack Review

Manufactured by:
Philip Werner
Version:
1
Price:
295.00

Reviewed by:
Rating:
5
On May 26, 2015
Last modified:October 13, 2016

Summary:

The ZPacks.com Arc Blast Backpack is an ultralight cuben fiber backpack with an external carbon fiber frame that available in three sizes: 45L, 52L, and 60L. Weighing just 17.4 ounces in the 60L version (shown here in orange), the Arc Blast is rated for 30 pound loads making it ideal backpack for thru-hikers and lightweight backpacking trips with up to a week's worth of food.

Zpacks.com Arc Blast Ultralight Cuben Fiber Backpack
ZPacks.com Arc Blast Ultralight Cuben Fiber Backpack

The ZPacks.com Arc Blast Backpack is an ultralight cuben fiber backpack with an external carbon fiber frame that is available in three sizes: 45L, 52L, and 60L. Weighing just 17.4 ounces in the 60L version (shown here in orange), the Arc Blast is rated for 30 pound loads making it ideal backpack for thru-hikers and lightweight backpacking trips with up to a week’s worth of food.

Cuben Fiber

If you’re not familiar with cuben fiber, here’s a fast primer. Cuben fiber is an ultralight material used by several ultralight backpacking manufacturers that is lighter weight and more rip resistant than conventional tent and backpack fabrics. For example, if a 2 pound tent or backpack made using silnylon or dyneema grid weighs 2 pounds, it will weigh approximately half that or 1 pound when made with cuben fiber.

The ZPacks.com Arc Blast Backpack is made using a hybrid cuben fiber and polyester fabric that gives it even more strength, prevents fraying, and canbe dyed in different colors.
The ZPacks.com Arc Blast Backpack is made using a hybrid cuben fiber and polyester fabric that gives it even more strength, prevents fraying, and can be dyed in different colors.

More technically, cuben fiber is a non-woven, laminate fabric made using ultra-high-weight-molecular polyethylene and polyester that produces an exceptionally strong and waterproof material. It’s also considerably more expensive because production is controlled by one company that makes it in small batches and because gear manufacturers have had to evolve manual fabrication and styling processes (glueing and taping as opposed to sewing) to create products using it. That price is unlikely to go down because cuben fiber products are too expensive to produce in large quantities.

The Arc Blast backpack reviewed here is constructed from 2.92 oz/sq yd cuben hybrid fabric. This material is cuben fiber on the inside with a protective layer of 50 denier polyester on the outside. The outer layer gives it even more strength, prevents fraying, and makes it possible to dye in different colors.

ZPacks.com has been making cuben fiber backpacks and tents for eight years and has built the highest volume manufacturing capacity (all USA-based) for creating ultralight backpacking tents, backpacks, clothing, and accessories using the material.

Internal Storage and Organization

The ZPacks Arc Blast Ultralight Backpack is configured as an ultralight backpack with a front mesh pocket and two side water bottle pockets, so you can keep most of the gear and food you need to access during the day on the outside of the pack without having to open the main compartment.

The front mesh pocket is fairly small compared to other ultralight backpacks and does not stretch which can make it difficult to fit rigid objects such as a wood stove or cook pot into it. On the flip side, the mesh weave is fairly wide, making it easy to see the contents of the pocket, although I wouldn’t trust its durability for off-trail use.

The Arc Blast is configured as an ultralight backpack with a front mesh pocket and two side water bottle pockets
The Arc Blast is configured as an ultralight backpack with a front mesh pocket and two side water bottle pockets

The side bottle pockets are sized to hold 1 liter soda or Nalgene bottles, which are reachable when wearing the pack, and have drain holes sewn into the bottom. They’re a tight fit however, when the pack bag is full, making it difficult to add tent poles or other gear to the pocket when a water bottle is carried.

The top of the pack closes with a roll top, dry-bag style closure that has a velcro strip to ensure the pack bag top is closed before you roll it shut. However, the end clips of the roll top only close on top of the pack and not along the sides, which can be awkward and catch if you’re hiking through overhanging vegetation.

The inside of the pack bag is cavernous in the 60L size and can really hold a lot of gear or food. The interior is also fully seam taped to prevent water from leaking into the pack when it rains or the pack is set on wet ground. The only openings into the main pack bag are dual hydration ports (there’s a reservoir hang loop inside the pack), which are located between your shoulder blades at the top of the frame.

When packing the Arc Blast, I’d advise you to keep as much of your gear as loose as possible if you need to maximize your volume utilization to carry a lot of gear or food, rather than packing it in a lot of stuff sacks.  The hybrid cuben fiber fabric used in the pack has very little “bend” in it and won’t wrap itself around bulges created by stuff sacks. If you must use stuff sacks, use ones that have drawstring tops that can vent excess air when stuffed. The pack bag on the Arc Blast is sufficiently seam-taped and water-resistant that you don’t need to use (so-called) waterproof stuff sacks when packing it.

Daisy chains sewn onto the front of the shoulder straps make it easy to attach accessory pockets.
Daisy chains sewn onto the front of the shoulder straps make it easy to attach accessory pockets.

External Attachment Points and Compression System

The Arc Blast provides an impressive array of options for attaching external gear to the outside of the pack. Many of these attachment points can also be used to add accessory pockets sold by the manufacturer, third party products such as external camera pockets, or trip-specific cordage solutions you whip up on the fly to carry bulky gear.

First off, the Arc Blast shoulder straps and hip belt have daisy chains sewn across them. They’re a little crude looking but it’s easy to add pockets using quick-attach tri-glide buckles or cord.

Thermarest Zlite foam sleeping pad strapped to bottom of Zpacks Arc Blast Backpack. Road walking along a stretch of the Bay Circuit Trail in Massachusetts.
Thermarest Z-lite foam sleeping pad strapped to bottom of Zpacks Arc Blast Backpack. Road walking along a stretch of the Bay Circuit Trail in Massachusetts.

The pack also comes with a fairly unique way of attaching a foam pad to the outside of the pack (shown above) that includes two cords attached at the base of the mesh pocket and the bottom of the pack, than are tightened using line loc adjusters. Despite marketing perceptions, most triple crown thru-hikers still carry foam pads because they’re far more durable than air mattresses, and this attachment point is a great place to carry a foam pad like this, out-of-the-way.

While the Arc Blast comes with a zig-zag style compression system, nothing prevents you from re-routing the cord(s) as needed.-1
While the Arc Blast comes with a zig-zag style compression system, nothing prevents you from re-routing the cord(s) as needed.

The Arc Blast has gear loops sewn to the sides of the pack and comes with a non-elastic cord arranged in a zig-zag pattern that can be used for compression or to secure gear to the side of the pack. In practice, I find that this strap geometry makes it difficult to secure or release bulky gear like snowshoes to/from a pack, but there’s nothing to prevent you from removing it or adding additional cord/cord locks to create a more “horizontal” compression/external attachment. You can also run cords over the front mesh pocket to secure other bulky items to the outside of the pack.

Backpack Frame and Suspension

The Arc Blast has a ventilated back panel and external carbon fiber frame that makes the pack feel stiff and enhances load transfer to the hips
The Arc Blast has a ventilated back panel and external carbon fiber frame that makes the pack feel stiff and enhances load transfer to the hips

The Arc Blast is an external frame backpack with a lightweight carbon fiber that frame serves several functions.

  • The frame helps keep the torso length and fit of the pack the same, no matter how much weight you carry in the pack. This makes the pack easier to use for transitional lightweight backpackers who are less familiar with the nuances of fitting and loading ultralight backpacks.
  • The frame suspends a ventilated back panel that makes the pack more comfortable to wear in warmer weather, in part because your shirt will dry faster when you sweat.
  • When adjusted, the external frame creates a curve that concentrates the  load onto the back of your hips regardless of your waist size, allowing you to hike with a more upright and biomechanically efficient stance.

The effect of the curved external frame is further enhanced by the fact that the hip belt is sewn to the back of the pack, unlike backpacks where it’s less securely attached using velcro. A sewn attachment always trumps a floating one, providing a more continuous kinetic chain, so that pack moves when your hips move without any wasted or diffused energy.

When tightened, the frame forms an arc or curve that creates a space between your back and the back of the pack,while directing the load onto the back of your hips.
When tightened, the frame forms an arc or curve that creates a space between your back and the back of the pack,while directing the load onto the back of your hips.

To created the curvature, ZPacks recommends adjusting the frame so that the mesh panel is 2.5 inches off the back of the pack. This adjustment is made by pulling forcefully down on the line-loc cords that suspend the mesh panel. Unfortunately, these line-loc cords slipped repeatedly when I wore the Arc Blast, but this is easily remedied by tying a simple overhand knot in the cord so it can’t slip through the line-loc channel. If there’s an upside to the use of line-locs in many places on this pack, it’s that they make user customization and adjustments possible.

Unfortunately, the line loc tensioning system slips under  load. This is easily remedied however by tying an overhand stopper knot in the line.
Unfortunately, the line loc tensioning system slips under load. This is easily remedied however by tying an overhand stopper knot in the line.

Customization Suggestions

Whenever I test backpacks that are available with custom or add-on options, I make a point to obtain the base pack from a manufacturer to see if the vanilla model is fully functional for its intended use. This proved to be the case with the Arc Blast base model.

If you can afford to customize the pack or add a few options to it (most don’t require any sewn modification and attach using cords), there are a few that I would recommend to make the pack more convenient to use and bring it to complete parity with competitive products.

These include:

Adjustable torso w/ load lifter straps attached to frame ($8): Fit can be tricky with this pack because tensioning the external ventilated frame makes the pack noticeably shorter. Furthermore, ZPacks uses an unconventional heuristic of sizing backpacks based on an individual’s height rather than torso length, so that having an adjustable frame will ensure that you can dial in the fit of the pack to your exact physical measurements.  The adjustable frame also connects the load lifter straps to the frame instead of the pack bag, making them more effective.

Belt pouches (41.95/pair):  Hip belt pockets eliminate the need to open your pack frequently if you carry a lot of little things like Aqua Mira Bottles, bug dope, lip balm, food bars, sunglasses, hair ties, etc. If you’ve ever owned a pack with them, you’ll understand.

Top side pockets ($35/pair): These are pockets that can be attached to the side of the pack, at about shoulder height. They’re indispensable for storing wet or smelly items like a wood burning/solid fuel stove and cook pot ,which you don’t want to put into the main compartment of the pack, and which may be too big to fit into the front mesh pocket.

Lumbar pad ($12): Helps improve load transfer of frame to your hips if you have a flat ass or square hips.

Backpacking in New Hampshire's White Mountains with the ZPacks Arc Blast Ultralight Backpack
Backpacking in New Hampshire’s White Mountains with the ZPacks Arc Blast Ultralight Backpack

Recommendation

The Zpacks Arc Blast Ultralight Backpack is optimally configured for multi-day backpacking trips and three-season thru-hikes with many innovative features including a ventilated external carbon fiber frame and seam-taped cuben fiber construction. Weighing just 17.4 ounces in the 60L size, it’s a deceptively sophisticated backpack that works extremely well in its base configuration but can also be enhanced using add-on accessories sold by the manufacturer or third-parties. While not as polished looking as other ultralight backpacks made using more conventional fabrics, the Arc Blast 60L is a durably constructed, feature rich, and easy to customize pack making it a very attractive option for backpackers who want to slash their gear weight without sacrificing on comfort or fit.

Likes:

  • Shoulder pads are free to rotate around different chest shapes
  • Side water bottle pockets are reachable while wearing the pack
  • Side water bottle pockets are solid panels with drain holes and more durable than mesh ones
  • Compression and external attachment system can be customized using gear loops located around perimeter of pack
  • Pack add-ons can be added any time after purchase and be trip-specific
  • Pack is nearly waterproof with seam taped seams (except for hydration ports)
  • Orange color is rad. I love it!

Dislikes:

  • Roll top closure does not secure along sides of pack, only on top
  • Front mesh pocket is not stretchable and quite limited in size
  • Non-standard sizing system

Visit Zpacks.com for full backpack specifications

Disclosure: Philip Werner (SectionHiker.com) received a loaner Arc Blast backpack from ZPacks.com for this review. 

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35 comments

  1. I have been using the arcblast for about two years now and have really been impressed with it. Some where on Facebook there is a picture of me climbing out of a stream, in January, when I misjudged a crossing. The stream was chest deep, and very cold, but none of the gear in my bag got wet. Could have been a very unpleasant night otherwise. I have a lot of Zpacks gear and have been really happy with the quality. Zpacks customer service is also top notch. Always responsive when I have a question.

    • Joe’s built an impressive company with unique products and a fantastic customer following.I bought my first cuben fiber backpack from Zpacks in 2010, an earlier version of the Blast, and it’s cool to see how their external frame concept has developed since then. It’s all pretty amazing, when you consider how different cuben fiber is from regular fabric and how it requires completely different skills and technique to run a business based around it.

  2. Joe V. at ZPacks is easy to work with. He can do some custom alterations when you buy the pack. Rob Earle had a single tall pocket added to one side, a very desirable option for many (damp or wet tents, hammocks, poles & fishing rods, etc.) My daughter also wanted one that way, but in a much smaller size, of course.

    This is perhaps the only external framed pack at around one pound out of the box. While I generally dislike external frames, because they are too stiff for my lighter 20-25# loads, this one allows more flexibility for hip movement (that diagonal twist between shoulder and hips) than others.

  3. Just tried my new Arc Haul this weekend. I think I’m in love. I may never buy another backpack again.

  4. Another great review. I have the 60 and it’s a workhorse. My base fits easily in a 40 but the extra space is great for those 5-7 day treks with food or Scout outings when I have to pack extra for the troop. The extra roll, when not fully packed, also helps with water resistance. The 60 also accommodates a bear vault inside in a vertical position. The load lifters are a smart option on the 60. I thought they would be a stress area but they haven’t shown any wear. I also use the hip and shoulder bags and the lumbar support. Haven’t opted for the side pockets. The concern with the top roll vs the side clips could be easily remedied by adding clips to the side compression lines, but if you are using the add on side pockets they may get in the way. Red Beard has a post AT review of the AB and it speaks worlds to its durability. I believe he’s using the same AB on the PCT as we speak.

  5. A very timely review Philip, as I’m down to this or the HMG Windrider 3400 for my Long Trail thru-hike in September. From what I’ve seen, this looks like it might be the winner!

    • This is a nice pack and should work well on the LT.

      If you order a pack from ZPacks made sure you order it about 3 months before you need it because they’re experiencing long order delays this time of year.

  6. What considerations would you give the Arc Blast vs the Mariposa for someone who mainly does 3-4 day hikes with an occasional longer hike thrown in?

    • I think it’s going to really boil down to fit, how much you want to spend, and how much you’re willing to wait They’re both excellent packs. Try both if you can. Also, I suspect that the Mariposa is in stock, and it’s about half the price of the Arc Blast.That’s almost always the problem with cuben…it’s almost always backordered by a month or more unless you buy a pack in the winter.

      • At 6’6″ fit is always a challenge. Thanks for the detailed reviews as usual.

      • Ouch. Perhaps you should get Zimmer or McHale to build a custom pack for you, That might be to only way to get what you need.

      • Philip. How is the padding on the shoulder straps and hipbelt? I am rather “boney” so need extra padding in those areas.

      • Z Packs sells extra shoulder pads. I don’t use these but I do use the lumbar pad and love it. http://www.zpacks.com/accessories/strap_pads.shtml

      • vicky…that padding is rather thin, so if you really want an Arc Blast, you may have to contact ZPacks and ask fro thicker padding, or add on the ones Hodad linked to above. I’ve had a 28# load in this pack and it was for an overnighter and I absolutely love it. This is my winter pack and you’d be surprised how well quilts and down cram down into it.

      • Vicky, the padding on the Zpacks bags are deliberately thin, narrow and firm so that they will contact firmly on the bones (hips and collars) without compressing down and pressing onto the surrounding soft tissues. This is very comfortable as the weight is on the load bearing bones, rather than the soft muscles which would impair circulation and movement.

      • We need a Big and Tall gear maker. At 6’4′ and wide through the shoulders all my stuff ends up being xLong X xWide. Not all of us are built like ultramarathon runners.

  7. I am a 58 yo recreational hiker (scouts and solo). I am not ultralight but I am incrementally taking off weight as a grow older. I have the 52 liter arc blast. I think it was the largest one available at the time. I love it but if I were buying again, I would definitely opt for the 60 liter. I might switch to the load hauler version since I start my trips at about 35#. My trips usually require a full sized bear can. Yes it fits (as stated on the web site), but not if I want to carry my gear too. It first I thought I would need to send it back but my solution was to strap my bear can horizontally on top of the pack. It just required four buckles, two 1/4″ straps, and velcro to secure the strap to the can. Overall I am very happy with the act blast. I sometimes exceed the 30 lb design weight but it remains quite comfortable. I have both the arc blast and a zpacks tent. If I were doing it over, I would get both from zpacks again, just move to slightly different models. This year I will accessorize my arc blast with upper side pockets and their “multi-pack” to use as a lid. That should give me some flexibility and added capacity when that is needed.

  8. Great review. Are you sure about the weight? I think the 60L is 21 ounces.

  9. And, ZPacks redesigned the harness system since Philip’s pack was made, which added a few ounces to the overall weight, and several pounds to the carrying capacity of the pack. Connections between the frame, shoulder harness, hip belt, and bag have been beefed up, and adjustable height is now standard. Well worth the few ounces of added weight IMO. I’ll be taking my new orange ArcBlast out for a 4-day shakedown next weekend. Why did I buy it? Hiked with a guy using an ArcBlast last summer, and your positive review clinched it. Thanks for all you do (and say).

  10. This was my Arc Blast order in 2015. It’s a good idea to leave off the hydration port to maintain the water resistance of the pack.
    Description:Leave off Hydration Port, Item#:
    Description:Load Lifter Straps (.2 oz), Item#:
    Description:Arc Blast Backpack, Item#: , Volume: 60 Liters , Color: All Army Green w/ Black accents ,…

  11. Michael Bearden

    Received two packs and triplex tent on time… very light… The packs have standard features that I had read were custom add on features… ie: the load lifters, and adjustable fit shoulder straps.. Pleasant surprise… I am very happy with my purchase.. I will give more feedback when I have trail time on these products. I am an old dude, so weight and comfort are critical to me.

    Kind Regards,

  12. sewn attachment always trumps a floating one, providing a more continuous kinetic chain, so that pack moves when your hips move without any wasted or diffused energy.

    I disagree with above, reason is! A pack where the hip belt moves with the up and down movement of the hips and from side to side while keeping the pack stable is much more efficient and comfortable.

    Willem

  13. Follow up: My new Arc Blast 60 weighed in at 20.8 ounces, which is under the spec weight. Awesome! I’ve adjusted the pack and really like the fit. The only thing I do not like is that the opening on the two side pouches make it difficult to retrieve a water bottle without throwing a shoulder out. The Osprey Exos has a stretchy mesh that and the opening is lower and slanted forward. I may ask them modify one of them.

    • I also have trouble reaching the side pouches on the Arc Blast. I have the ULA Oam and it’s the same on that pack. The side pouches work great for your cook and latrine kits with room to spare. Try the shoulder strap pockets for your water bottles. They work amazingly well. I made some DIYs viewed here https://www.hammockforums.net/gallery/showimage.php?i=27867&catid=member&imageuser=8052 .

      A side note from the school of hard knocks… I frequently check my pack for weekend excursions on business trips (within a duffel pack) and have arrived with broken frame battens. My solution has been to remove the battens, bind to hiking poles (Z-poles) with rubber bands and wrap all with my reflective sit pad/cozy. I’ve also started removing the stays for car transport if there is a likelihood of breakage such as shuttles to trail heads in groups etc. If you don’t remove the battens/stays at least take the tension off.

      • How does the Zpacks compare to the ohm

      • The Zpacks Arc Blast has a larger volume, cooler back, better ride, water tight (opt out of the bladder hose port). I wish the front gear netting on the Zpacks was the same material as the OHM. It’s less flexible and more fragile, but there may be a weight savings over the OHM. As fragile as the Zpacks frame is the OAH’s frame is a complete joke, unless perhaps you could integrate the two arrow shaft like stays into your kit for multi use. I understand the 2016 Z-AB have upgraded stays for durability.

  14. I have the Arc Blast 60 lt with top side pockets, waist belt pockets, waist belt pad, split side compression strings, and no water tube hole in the top. Weighs in at 1lb 9ozs.

    On first trying it on I thought I had ordered too small a size waist belt, because the padded wings barely covered my bony hips. I have since walked the High Route across the Pyrenees, Atlantic to Med, 500 mls, and 122,500 ft of mostly steep and rocky ascent. It took 35 days, and I carried between 17 lbs and 28 lbs, and have to say this was the most comfortable pack I have ever carried. The suspension looks extremely simple, but somehow it transfers weight to your back and hips perfectly. The split hip belt adjustment helps here greatly, and the lack of full wrap round didn’t matter at all.

    I set the arc in the frame initially, but when then strings slipped I didn’t bother with the arc again. The load sat close to my back and I didn’t miss the ventilation. I also didn’t use the sternum strap.

    Sometimes I didn’t adjust the belt or shoulder straps for days at a time, it was so comfortable. Other times it was nice to be able to play with the load lifters to vary the carry a little.

    I liked the top closure of the hip belt pockets, but did NOT like the closure of the optional top side pockets. They use the thin elastic shock cord which is not adjustable, and does not give a very secure closure, and I would prefer a thicker cord and toggle arrangement. In fact the end of one cord became unattached and I nearly lost my Hexamid tarp that lived there. I resewed the cord and clipped the tarp on with a mini crab as well.

    Another minus is the fragile nature of the Cuben fibre base. I slipped on a couple of steep gravelly descents, and of course the bottom of the backpack then hit the ground. Also putting the pack down on rock and picking it up multiple times causes a little wear. As a result, there are a few places where I can almost see right through the material. I will have to either stick on a Cuben patch, or, preferably, sew on a dynema base. Zpacks use dynema, so perhaps they could do that themselves as another custom option.

    I liked the roomy front mesh pocket, which is accessible even when the pack is fully done up, which means you can put in the sit mat you forgot about until you stood up.

    Overall a great lightweight pack with lots of features, but with a few areas where it could do with a little beefing up.

  15. The carbon frame snapped on my second use of the pack in the alps. Zpacks sent me some new ones but they were tricky to reinsert and the pack never balanced the same way again.

    On the 10th day of my JMT hike the bottom split open 2 inches with multiple abrasions breaching the waterproofness of the bag. Zpacks responded by sending me “repair patches” (so much for guarantee )

    The frame was pretty useless at keeping airflow through your back because the carbon poles wouldn’t bend back in the right direction with the bear canister in the pack. As a result the canister was constantly pertruding into my back.

    The zips on the hip pouches often snagged and was not at all user friendly, they are attached to the bag via two badly constructed elastic bands which are not secured when the pouch is removed. The side bottle holders are too shallow and unreachable with the pack on my bottles fell out several times.

    Overall an unreliable and uncomfortable bag to bring on a backpacking trip and not worth the weight savings.

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