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Zpacks Arc Air 50L ROBIC Backpack Review

Zpacks Arc Air 50L Robic Backpack Review

The ZPacks Arc Air 50L ROBIC Backpack is an ultralight pack with a curved carbon fiber frame made with 100d and 210d Robic nylon. The backpack is a roll-top pack with a front mesh pocket, side water bottle pockets, and sleeping pad straps. It has an adjustable torso length so you can get a personalized fit and is available in five different hip belt sizes. While the hip belt does not have pockets, they can be purchased and attached to the pack, along with a wide range of other accessories including shoulder strap pockets, side mesh pockets, a Y-strap for carrying a bear canister, and ice axe loops. A 60L Robic version of the Arc Air is also available.

Specs at a Glance

  • Weight: 21.2 oz / 600g
  • Volume: 50L total: (37L main body, 2.5L each side pocket, 8L center pocket)
  • Pockets: 3
  • Fabrics: 100d and 210d Robic Nylon, Lycra Mesh
  • Hydration compatible: No
  • Bear canister compatibility: Vertical for a BV500, but you’re likely to feel it poking you in the back (I do).
  • Max recommended load: 30-35 lbs

Backpack Frame and Suspension

The Arc Air 50L has a curved backpack frame like Zpack’s other packs, which is designed to let air flow between your back and the pack so your clothes dry faster when you perspire. It has a new frame that’s different from the one used on Zpacks other packs like the Arc Blast and the Arc Haul. The mesh back panel has been removed completely, the vertical frame stays are much thicker, and they’re sewn into the backpack improving durability and giving the pack a more polished look. The degree of curvature is also fixed, with a depth of 2.5″ (6cm), and not adjustable.

The vertical frame stays along the sides are now sewn into the backpack.
The vertical frame stays along the sides are sewn into the backpack while the top two crossbars remain visible.

The new frame has some pros and cons.

The pros: The pack is simpler and less confusing to adjust which is a good thing, especially for new Zpacks customers. It’s also more durable because there are fewer moving parts and things to snag and tear on vegetation. I also think that the frame is stiffer, more responsive, and better at carrying heavier loads, like water carries, than the previous frame architecture. Part of that performance improvement may also be due to the fact that the pack bag sits closer to your hips because it has less of a curve.

The Arc Air has a shallow curve that lets air flow behind your shirt.
The Arc Air has a shallow curve that lets air flow behind your shirt.

The cons: The curvature depth isn’t really deep enough to provide a lot of ventilation when wearing multiple clothing layers. There’s some airflow (about an inch) behind your back if you’re just wearing a baselayer, but if you wear a hoodie or a jacket, they fill in and block the air gap. Then again, that’s a case where you probably want a bit less airflow in order to stay warmer.

If you prefer having a deeper and adjustable curvature with a mesh back panel to ensure that your clothing doesn’t block the air gap, you should probably buy the Arc Blast or an Arc Haul instead. Other than the frame, there’s not that much of a difference between the three packs other than the fabric they’re made with.

Incidentally, you can retrofit an Arc Blast or Arc Haul backpack to use the new Arc Air vertical frame stays. Contact Zpacks to purchase the replacement stays and to receive instructions.

Adjustable Torso Length

The Arc Air has an adjustable length frame (torso length) so you can dial in a good fit. The pack doesn’t arrive with any documentation that explains how to adjust it, but there’s a good video on the Zpacks website that explains what to do, although it’s for the Arc Blast series of packs.

It’s remarkably simple. Once you have the rest of the pack adjusted, you’ve packed the pack with a light load and put the pack on including the hipbelt, you push the shoulder pads down so they wrap around the top of your shoulders without any gaps showing. This positions the webbing that connects the top of the shoulder pads to the back of the pack at the proper length. That’s it. It’s a pretty ingenious design.

The Arc Air comes with S-shaped shoulder straps that mold around well developed (female and male) chests.
The Arc Air comes with S-shaped shoulder straps that mold around female and male chests.

Shoulder Straps and Hip Belt

While Zpacks doesn’t make men’s and women’s specific backpacks, the shoulder straps on their packs are female-friendly with an S-shape that curves around women’s chests. The straps are also attached to the back of the pack with webbing instead of being sewn directly to the frame, which allows them to rotate and conform to the sides of your torso instead of lying flat on your breasts (and smashing them flat). This is beneficial to men and women, alike. The difference can take a while to get used to though and the space between the shoulder straps may feel a bit wide when you start using the pack.

The shoulder straps have load lifters that are attached to the frame and can be pulled forward to bring the pack closer to your back to counter any backward lean caused by a heavy or unbalanced load. There are also daisy chains sewn to the front of the shoulder straps so you can attach pockets to them easily or move the sternum strap position up and down.

While the hipbelt has a center buckle, you can adjust the fit on the top or bottom half of the belt using two webbing straps on each side. This is another female-friendly feature that lets you adapt to the shape of men’s or women’s hip shapes. The hipbelt is removable, but very tightly anchored on the frame, so you don’t lose any control or load transfer from the frame to the hips.

The Arc Air focuses the pack weight on the lumbar area of the back which some people may find a bit uncomfortable.
The Arc Air focuses the pack weight on the lumbar area of the back which some people may find uncomfortable.

In fact, the load transfer to the hipbelt is downright awesome, it’s lightly padded so it won’t slip over your hip bones, and if you wanted to, you could easily adjust the pack so that 80% of the weight rides on your hips and 20% on the shoulders. Like the shoulder straps, there are attachment points on the outside of the hip belt where you can add pockets.

It’s worth mentioning that some people may experience lumbar discomfort using the hipbelt because it does not distribute the load across the entire base of the backpack, but focuses it on a narrower centralized area, between the vertical frame stays. I got used to this pretty quickly, but you may want to add a lumbar pad (sold by Zpacks) to add additional padding to this area if you experience discomfort.

Backpack Storage and Organization

The Arc Air 50 is a rolltop with a very standard ultralight pack design. It has a large main compartment, easy-to-reach side water bottle pockets, and a large front mesh pocket. The top of the main compartment closes with a velcro strip (some people hate this) and the buckles at the ends can be connected to one another or to buckle/webbing along the sides of the pack. There’s also a single webbing strap running from the back to the front of the pack, over the rolltop that can be used to lash gear to the top of the pack.

The curved frame doesn’t really interfere with packing bulky objects, which can be an issue with some ventilated backpacks that have deep cavities behind the back. But you’re going to want to pack items with hard edges closer to the front side of the main compartment (the mesh pocket side) rather than the rear, facing your back, so they don’t poke through the fabric and cause discomfort. This occurs because the spacing of the Arc Air’s vertical stays don’t provide the same degree of protection as you find on packs with more centralized frame stays.

The front mesh pocket is tightly tensioned but you can still get a lot of stuff into it.
The front mesh pocket is tightly tensioned but you can still get a lot of stuff into it.

The front mesh pocket is tightly fitted but has enough stretch that you can get a stove system into its, water reservoirs, snack bars, and rain layers without much difficultly. It has a fine weave and good transparency but could be ripped up by vegetation if you venture off-trail with it.

The water bottle pockets can hold 1L Nalgenes or 2 x 1L Smartwater Bottles and are slanted forward making them easy to reach while wearing the pack. They also have drain holes in the bottom to drain water and prevent it from collecting inside. The Arc Air does not have an internal hydration pocket or hook to connect a reservoir and there is no hydration port.

There are small webbing loops along the seams where you can rig up your own side compression or attachment points with cord.
There are small webbing loops along the seams where you can rig up your own side compression or attachment points with cord.

Attachment Points

The Arc Air has sleeping pads straps, numerous gear loops, and daisy chains where you can attach extra gear to the outside of the pack. You don’t have to spend a lot of money to do this and a little cord, mini-biners, and cord locks can go a long way to customizing the pack for your need.

Alternatively, you can purchase add-ons from Zpacks from water bottle sleeves and shoulder pouches to hip belt pockets, to top side pockets, and a V-strap for carrying a bear canister. While these add-ons are very functional, they also add a lot of cost to the backpack that other manufacturers bundle in with the base price of their backpacks.

The pack includes sleeping pad straps which make it easy to carry a bulky foam pad
The pack includes sleeping pad straps which make it easy to carry a bulky foam pad

For example, let’s say you wanted to add 2 hip belt pockets ($29 each) to the Arc Air, which is a pretty standard feature on most ultralight backpacks from other companies. That’s $58 bucks. A V Top Strap is another $10. Ice axe loops are $10. Trekking pole holsters are another $10. It all adds up pretty quickly and you’re looking at close to $400 for a nylon backpack, which I think is pretty steep.

Arc Air Robic vs Arc Air DCF

The Arc Air 50L is available in Robic Nylon ($299) or DCF ($325) which is a pretty small price difference. How would you choose between them? I don’t think there’s a clear-cut answer to this question.

If you’re not up to speed on Robic, see our article: What is Robic? for an in-depth look at this fabric.

Personally, I prefer DCF over Robic because it doesn’t absorb water and it’s easier to repair with tape since I don’t sew. While the bottom of all of my DCF packs have all worn through in 3 years of hard use, DCF is much better for off-trail hiking, which I do a lot, because vegetation slides off it rather than puncturing it. I’m also ok with replacing my multiday backpack every few years so I don’t really care about wearing through the DCF at the bottom of the pack.

Robic Logo

The high wear areas of the Robic Arc Air 50L are made with 210d Robic, which is pretty robust, but not as good as the 400d Robic used by other backpack manufacturers like ULA. If you don’t mind the fact that Robic absorbs rain despite its PU coating (this doesn’t add much weight, it’s just a hassle) I think it’s a good choice for trail-based hiking in terms of abrasion protection, particularly if you want to keep your pack for a lot longer than a few years. That abrasion occurs whenever you put your pack on the ground or when you rub up against rock walls.

Still, I do find it a bit confusing that the Arc Air 50L Robic is only $26 less than the Arc Air 50L DCF; I would have that the Robic Arc Air would be priced significantly less since it’s just nylon and probably requires a lot less labor to make than a DCF pack.

Comparison Table

Make / ModelVentilatedAdjustable TorsoInterchangeable HipbeltsWeight
Osprey Exos 48YNoNo2 lbs 9 oz
Osprey Eja 48YNoNo2 lbs 7 oz
Gregory Optic 48YNoNo2 lbs 6 oz
Gregory Octal 45YNoNo2 lbs 5 oz

While all of these packs have ventilated frames with suspended mesh back panels, none of them have adjustable length torsos or interchangeable hip belts. They also weigh significantly more than a Zpacks Arc Air 50L Robic backpack which weighs 1 lb 5.


The Zpacks Arc Air 50L Robic Backpack is an ultralight roll-top backpack good for on-trail hiking with a ventilated frame, an easy-to-adjust torso length, and interchangeable hipbelt sizes to choose from, so you can dial in a near-custom fit. Weighing 21.2 oz, the curve of the Arc Air’s frame is fixed and not adjustable, making it much simpler to use, especially by customers new to the brand.

While the Arc Air 50L Robic is pricy, especially after you add on a few “accessories” like hipbelt pockets, there really isn’t anything out there that comes close to the value, in terms of fit, ventilation, and gear weight offered by the pack. My only reservation with the Zpacks Arc Air is that hard-edged objects can poke you through back panel if they’re packed behind your back and not toward the mesh side of the pack. But it’s easy to work around that limitation when packing your stuff in the backpack.

Disclosure: Zpacks provided the author with a backpack for this review.

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  1. Great review.

    That pricing does seem strange at first. Looking at Ripstop by the Roll where I buy a decent bit of material for MYOG, you can get 210D Robic for $11.50 per yard while the closest DCF that I can find to what ZPacks uses is $35-$46 per yard. Looking at their wholesale prices, you can get a full roll of 2.92oz DCF (ZPacks uses 3.1oz) for $19.60 per yard (39.4 yds for $771). Taking a similar margin, the Robic can probably be had for $6 per yard whole sale so a difference of around $13 per yard. Estimating about 2 yards for a pack (probably closer to 1.5 yds), it is probably $25-$30 cheaper per bag in materials all other components being equal. The few times I’ve worked with DCF, I haven’t notice much extra work in the handling or manufacturing steps so it might be a lot closer to the cost to manufacture as their DCF packs.

  2. I have an Arc Blast that I love but need to replace and was planning on doing so with another Blast. Is there any compelling reason to replace with an Air? Everything I’ve read doesn’t make it seem so. In fact, what was ZPacks reasoning in creating the Air when they already have the Blast in your lineup? Seems like they should have just upgraded to a Blast v2. I’d love to hear your thoughts.

    • I think they should have probably kept the mesh on the Air but made it non-adjustable to maintain the air gap (keep your clothes out of it) and because the Osprey Exos has it, which I suspect is their main competitor by sales volume. Sometimes you want people to compare you against a competitor because you can piggyback on the consumer education they’ve already paid for. For example, a Robic Air with mesh would beat the Exos on weight every time.

      I also suspect that Zpacks needed a more shrink-wrapped product than the Blast or the Arc Haul to sell to people who aren’t thru-hikers used to dealing with cottage gear. The adjustable curve on the Blast is not really a consumer-friendly feature for a retailer like REI to support. There’s too much handholding and education required. It works with the smallish UL community because it is a community, but without that social support, it’d be too costly to support in pre-sales and post-sales. That’s just a guess. I do wish Zpacks the best and hope they do go to retail because I am SO sick of Hyperlite’s marketing. :-)

      I’d get another Blast if you like it.

      • 2019 at Lake Moreno after the 20 miles from the Border I saw a hiker with his Brand New Arc Blast. He said it was great but did NOT even know you could put an arc in it to get it off your back…..He wore it flat as a pancake. Had NO IDEA !~
        Great review……

  3. Phillip, thanks for the review. I have an Arc Haul that I converted using the Air stays and have been considering an Arc Air as my kit has grown more compact for shorter and summer multi day trips. Zpacks was helpful in doing the conversion. I like the permanent Arc that the new stiffer Air stays provide and not having to fiddle with setting or adjusting the Arc. I experienced the issues you mentioned with hard edged object poking thru the back pack fabric with both the original stays and the new stays on my Arc Haul but managed to solve it (at a small weigh penalty) by using a piece of chloroplast plastic honeycomb board attached to the stay side of the pack using velco. I was questioning Zpacks decision to do away with the zig zag compression cordage on the Arc Air packs which works quite well on my Arc Haul. Has this limited the ability to provide adequate compression adjustment on the Arc Air pack?
    Thanks again for the review.

    • That’s a great point to raise Dana. The compression/side attachment options aren’t that great on the Arc Air. They do have small webbing tabs at the top of the pack that you can use to route cord (see 7th photo in the review where I did it to carry my fishing rod), but there are only three attachment positions on the side so you can only get one diagonal zig by running cord if you want to really compress the middle part of the load. Whether that is necessary is another question, because you get a lot of compression mid-pack just by the shape of the frame. It’s the top where you need it the most.

      I’d say that the compression on the Arc Air is passably adequate. For my personal loads, I care more about having the ability to attach things to the sides of a 50L roll-top pack than side compression. For example, it would be very difficult to use the Arc Air to carry snowshoes on the sides of the pack which is where I like to carry them, or for that matter a medium-length fishing rod case that is shorter than the one I have pictured. BTW – the roll-top webbing straps can be connected over the front mesh pocket to carry snowshoes if you don’t mind sacrificing the top compression.

      But of all of their packs, the Arc Air definitely has the weakest side compression.

  4. I’ve read reviews of the carbon stays twisting on the arc air packs, causing the user to have to remove the pack to fix them. Have you experienced this?

  5. I used this pack for 2 months and 1008 miles on the AT this year, and I have good and bad things to say for sure.

    First, the pack is awesomely light, the robic is tough, and I had no problem fitting everything I needed into and onto the pack. The shoulder straps were very comfortable, and my back stayed cool when the stays were working properly (more on that in a minute). No buckles broke, no seams came undone, and the back and side pockets worked great!

    Unfortunately, Zpacks made a bunch of these with factory defects early on (per the customer service rep I spoke to). The stays rotated, and even popped out of their holders within a week of getting on the trail. By rotating, the stay would then be curved into my back instead of away from it. The metal cross members connecting the stays also fell out occasionally. I would have to take the pack off several times a day and jam the stays back in and rotate them back around. After a couple of weeks, one of the stays actually wore through the bottom of its nylon holder and popped out the bottom, poking me in the hip. The good news is when I took a zero in Killington, VT, I called Zpacks, and they sent a new one ahead for me to pick up 4 days later. They asked that I send my damaged one back for repair, which I did. The new one had been sewn better, and worked perfectly for about 2 weeks, at which time, the stays started to occasionally rotate just like the ones on the old pack had. It happened at least once every other day from that point on, and the cross members also fell out three times in those last two weeks. The nylon at the bottom of the stays did not wear through on the new pack, but they both looked very worn. My guess is they would have lasted another 2 or 3 weeks.

    Beyond the major issues with the stays, the stitching on the belt rubbed on my lower back enough to give me sores, but a couple strips of duct tape took care of that.

    When you buy ultra light gear, you cannot usually expect it to last as long as a regular gear, but I believe there is no way the Arc Air would have lasted for even 2/3 of an AT thru hike, had I been doing one.

    But, man, was it light!!!

  6. I really appreciate your reviews Phillip! One question regarding the packing of the Arc Air – in your review of the Arc Blast you mentioned it was best to pack your gear as loose as possible (to maximize volume utilization), and avoid the use of drysacks, using only drawstring bags if necessary. Does the same logic apply to the Arc Air? Thanks, Joe

    • It would if you hiked in dry terrain. In wetter climates, it kind of depends on what kind of pack liner you use and how much you trust it. One trick, I sometimes use is to poke a hole in my roll top dry bags to get more air out. I know that sounds crazy, but I value them more for compression since it’s highly unlikely that my pack liner/plastic bag is going to leak much. It also depends on where in the pack you pack things. I like to use drawstrings higher up in the stack. Not sure if that completely answers your question…

      • That is another really interesting perspective. Your solution offers the best of several worlds – compression, dryness, organization. How do you make a hole so that it doesn’t weaken the fabric of the bag/sack?

        I do use a trash compactor bag as a liner but don’t have a lot of stuff sacks right now and have just been relying on quart/gallon Ziploc freezer bags. Most of the time I leave the ziplocks slightly open so that air can vent as they are compressed by the contents of my pack. Trying to move beyond them to more long-lasting solutions such as zippered/drawstring/rolltop stuff sacks and bags. Lots of little subtle differences and pros and cons. I will read the articles on your site and go from there. Thanks for everything you do for people who enjoy the outdoors. I am an engineer by education and pretty new to the world of backpacking – in my many hours spent researching gear, etc you and your site have been an invaluable resource.

        Just a thought – do you have an article comparing the pros/cons of different packing approaches? I searched a bit but might not be using the right keywords.

        • It’s just a very small hole. :-) Plus, most stuff sack fabrics don’t tear that much – dyneema, ripstop, etc.

          There’s no real reason you have to use fancy outdoor stuff sacks…your approach using Ziplocs is perfectly good too. I used to like using the plastic bags that my folded dress shirts came packed in from the dry cleaner, back when I had dress shirts….many years ago.

          I have some posts scattered around the site on packing. My approach often varies depending on what I’m carrying, time of year, precipitation. etc. In the height of summer, I can just throw everything into the pack loose if I want because there’s so little of it, except some things I always keep packed together like electronics, first aid, food, stove. But when it gets colder, then I need to worry more about compression and denser packability. Don’t forget about using gear that is more packable. For example, I use a synthetic insulated vest instead of a fleece vest when space is tight in my pack because the vest is easier to pack loose in all the little nooks and crannies in my pack. I guess my biggest piece of advice is don’t assume that you’ll only have one gear list. Mine changes constantly depending on what, where, and when I’m going.

      • In early January a few years ago, I spent five days kayaking the Lower Canyons of the Rio Grande Wild and Scenic River with a couple brothers in law. My spray cover was more like a glorified coffee filter and easily allowed water to leak through the fabric into the kayak. I was never so consistently cold, wet and miserable for five days in my life… in other words, it was an awesome adventure! The only items that stayed consistently dry through that experience were the things I had in Ziploc bags. Don’t discount their utility in tough conditions. They work!

      • Thanks Grandpa, good illustration that bad weather makes for good memories!

      • Sazerac’s First Law of Camping: The amount of pleasure derived after the trip, ceteris paribus, is directly proportional to the amount of misery experienced while on the trip.

      • Yeah I really like my BA roll top bag + pad inflator can push out the extra air on the inflator side but still cinch it pretty tight to be 99% water tight. Unfortunately the current BA inflator sack only works with BA pads whereas my older version has cinch opening also works with our Thermarest and Nemo pads.

  7. Thanks again, I am working my way through different articles and learning a lot. Sometimes it’s easy to ask the wrong question when you don’t know your way around a topic. Appreciate your patience and sound advice. I am beyond the days of dry cleaning also, and really miss those nice hangers too! The best are some that I brought home from business trips to Germany; they are unpainted polished metal, and beautiful to behold.

  8. I disagree that the shoulder straps are female-friendly. The attachment point of the straps and load lifters is very wide. I was able to get the pack to be somewhat usable for me by threading the load lifter straps through the attachment points for a V-top strap. This pulls the straps in somewhat, so they restrict the movement of my arms less.

    I also don’t think the pack carries a bear canister very well. The pack bag swings side-to-side and flops around a lot, and the canister whacks me in the back.

    I have an older Arc Blast that carries a canister much better – The pack is much more stable, and the mesh back helps keep solid objects from bouncing against your back. The old Arc Blast also had narrower straps, with a narrower attachment point for the load lifters, which worked much better for my female form.

    The hip belt is nice on the Arc Air and doesn’t slip. I think the pack could be great for wide-shouldered men who don’t carry bear canisters, but doesn’t work well for this bear canister carrying woman.

  9. Worth getting this pack still? discounted right now at @245

      • Well what size would you go with if you had a “19 torso (seems small or medium fall under that size)?

        Also you seem to dislike the Sierra designs flexcapicitor but it’s on sale now and about $125 less worth considering at a discount? (down from 220 to 131)

        Thanks for the response (even if it’s seemingly obvious)

        • If you fall between sizes, it’s usually best to size up. I don’t totally dislike the the SD pack but I hestitate to recommend any pack for anyone without knowing what you want to for and where you plan to hike with it. Being on sale isn’t a great reason to buy a backpack.

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