new zpacks pack: the arc blast

The load lifters are sewn to the pack bag about 2.5" above the top of the shoulder strap attachment point (straps are sewn at an angle.) I asked for a little more torso length, so that distance may be more like 3-3.5" on a standard Arc. With the pack full they lift appx. the back 2/3-3/4 of the shoulder strap off the shoulder (2/3-3/4 of the strap area that would normally contact the shoulder.) A higher attachment point mounted to a frame would definitely lift more of the strap off the shoulder, but the straps are still a good addition to this pack IMO. I ordered them for the same reason I ordered the Arc frame – my back has a fairly pronounced curve. Arcing the frame stays and cinching the load lifters allows the pack to follow the curve of my back. Without a lumbar pad to kick the top back towards my head, I think the top 1/3rd of the Exo would have stood too far away from my shoulders.

The curved arc frame transfers the 20lbs I have in it very solidly to the small of my back though, and so far I find myself fidgeting with the shoulder straps a lot less than other packs I've tried. I stuffed my quilt into the bottom and it makes a nice 'lumbar pad'.

I'm scheduled pretty solid through tomorrow night but will try and take some pics of the load lifters this weekend.

"I'm scheduled pretty solid through tomorrow night but will try and take some pics of the load lifters this weekend."

Thanks, Andrew. I'll be looking forward to your impressions. Also, it might be wise to do a test run with a half empty pack, when there will be nothing in the pack bag up high to give it the rigidity to support the load lifters.

Any EXTERNAL frame pack will have displace3ment off the back even more than teh Osprey packs. The long gone Trailwise external frame pack beloved by Colin Chapman has a back mesh "displacement" setup too.

Osprey used to have too much spacing but they modified that a few years ago and now most like the back mesh configuration.

"The long gone Trailwise external frame pack beloved by Colin Chapman […]"

Might ye mean Colin Fletcher? Back in the early '70s I bought a Trailwise pack because Fletcher recommended it in his book, "The Complete Walker." It was a sturdy, sensible pack with voluminous room. I have no idea when I lost track of that pack, it was three–maybe four–lifetimes ago.

So a long overdue report on my Arc Blast:

I took it on a 3.5 day/3night 40 mile loop on the July 4th weekend. I made a typical rookie mistake and packed far too much food for what was originally slated to be a 4.5 day/4 night trip. My pack weight on day one with two liters of water was about 25lbs. I must admit I missed the cushiness of my Vapor Trail a bit that first day. The Arc was not at all uncomfortable, but it was more noticeable on my back than the VT had been.

By day's end I realized I had totally screwed up the fit. When Joe mailed the pack he had the mesh tensioned so that there was a rather pronounced arch in the stays. I decided I wanted the pack to ride closer to my back and loosened the panel a bit. That was a mistake. With the pack loaded and on my back, the load was pulling against the mesh panel/stays enough that the frame was nearly straight. That night I adjusted the panel/stays back to where Joe had them in the first place and it made a big difference! The load transfer was quite a bit better, and for the rest of the trip I forgot completely about the Vapor Trail, despite the fact that my brother had borrowed it and was in front of me the whole time. The Arc was totally functional and very comfortable. No complaints whatsoever.

With the gear list I have now and proper food rationing my loads are going to max out around 20 lbs for 3-4 day trips. At this weight the Arc rides like a dream, I think I found the pack for me! Of course a couple more trips this season could change my outlook, but I don't forsee anything negative at this point.

Edit – regarding the mesh panel, there was a difference in ventilation once the panel was properly tensioned. However for me the fact that the Arc frame follows the curve of my back much more closely than the EXO would have is still the main draw for me.

I'm a very happy user of an exos 58, but as I've been getting lighter I've been looking for a true "UL" pack. This is the first I've seen with a mesh panel and was instantly drawn to it. The price is pretty good for such a light pack too! Although it gets a little more expensive to add extra pockets and the like.

I still have a bit of lightening to do and at least one more big purchase before a new pack (DuoMid or maybe a Hexamid…or a hammock…can't decide) but I'm definitely keeping my eye on this!

Joe, if you're reading this, would it be possible, maybe with an extra cross piece, to have the load lifters attach to a frame piece?

This response is coming a bit late but I can do pretty much any reasonable modifications to the packs if you email me and ask.

Yes sure I could add a cross bar at the top of the frame to attach the load lifter straps to.

By default the load lifters are sewn directly to the pack, roughly in line with the top of the stays. They seem to work well enough, but I don't normally use them myself.

Anybody?

So, I've spent approximately 8 nights/9 days worth of hiking with my Arc Blast now.

I find it very comfortable.

I treat the mesh kindly, as with all of my gear, and find it more than durable for my uses. – I have my shell gear, Steripen setup, fuel and PLB in the front mesh pocket…and that is it.

I don't notice any discomfort or imbalance from the spacing/mesh panel. I also have an Osprey Talon and another locally made trampoline style pack, so am used to this feeling anyways.

The hybrid material is ace too….very durable, and nice to work with.

I have found myself being more attentive to my packing style though…which is a good thing. I have reduced the number of dry bags down to 3…using the zpacks pack liner for my s/bag (zpacks -7 bag), spare clothes, mat (NeoAir) & pillow (OR UL Pillow). The top dry bag is Joe's large rectangular cuben fiber dry bag (still to arrive), however similar sized dry bag test runs allows me to put my ditty bag, food and condiments (zip locked), Eddie Bauer down jacket , and Evernew 600 with Starlyte set up quite easily….my Hexamid Solo stays in its own cuben dry bag for the sake of avoiding moisture getting through the rest of the bag. After all of this I still have some room to cinch up the side straps.

The reason why I thought it necessary to paint this picture is because the arched poles have a slight tendency to pull inwards at the top if I pack the bottom out and neglect to pack out the top…..causing the top to collapse in. This is expected though, and happens on packs…it's just more accentuated with the arched poles. This is easily remedied however, simply by packing my bag correctly in the first place!!

As for the load lifters…I have them on my pack, and find them a waste of time. I use them a lot on other packs that I have, but the UL nature of this pack and subsequent contents kinda renders the use of load lifters useless…for me that is.

I also grabbed a pair of both the shoulder pouches and hipbelt pouches…and I must say they finish the pack off really well. The shoulder pouches hold my GPS and sunnies etc., with the hipbelt pouches looking after snacks, gloves etc.

Really happy with this set up.

Although, I do reaaaally like the white. If anyone wants to swap for an Olive Drab (or work out a deal etc.) for a white let me know!! I know that is superficial, but hey, the white is sexy ;-)

Edit: I actually feel the pack sitting better on my hips, and there is nothing like a bit of breeze wafting through and over the mesh panel, cooling off my back….yep…I can feel it.

I have also made an order for Arc Blast and are now thinking if I should order any mods for it. Anything you would ask Joe to do if you had to place a new order with Joe for this pack? My setup is also close to yours but with a Hexamid Twin and a Jetboil Sol Ti.

Thanks – looking so much forward to get the package now ;-)

Hi Mikkel

The only mod I would make would be to remove the hydration tube port – I don't need it.

Perhaps the only other thing I would 'consider' is to have the whole pack seam taped. It would be nice to have a bomber, water-tight pack. This would take a bit of tape for sure, but the thought has crossed my mind. Although, two dry bags do the trick really well….so it may not be worth the hassle of seam taping it all.

I can see where you are going with this. I was thinking of buying a CF liner both as reinforcement to the backs fabric and to waterproff it.

" I got used to sweating when backpacking a long time ago. It comes with the territory."

Actually, not. I've been building my own internal frame suspended mesh backband packs for several years now. Of course, sweat is constantly evaporating from my back during exertion; but I have not felt moist, ever; and the back of my top, a polyester T or Polo, with or without a Polartec sweater, remains dry.

What's also nice, is that the back can flex without being constricted or rubbing against the pack.

The key to these packs is to have the tension adjusted just right for the minimum distance between the mesh and the pack, while maintaining enough distance and tension to prevent the pack from touching the back in all situations, like bending over, temporary heavy loads, etc. For this reason, when i first saw the pic of the Arc Blast, I thought, 'Why didn't I think of that!" The buckles allow precise adjustment of the tension, something not found on the Ospreys; hence the Ospreys are tauter than necessary to insure 'one size fits all.' The stays must be stiff enough to maintain tension without bowing more than is needed; thus keeping the pack as close as possible to the back without contact. Choice of nylon or polyester mesh also enters into the equation, as nylon is more elastic.

Durability of the mesh is just a matter of what material is chosen. The 'rawhide' mesh (the one with the little diamond shaped openings) is pretty bombproof, but for an ultralight pack, something lighter might be preferred. Leno mesh can develop runs if too much tension is applied, but is around an ounce lighter per square yard.
There are others available commercially that Joe had to choose from.

Thanks to Joe for this design. It sounds from the users' posts that it is working very well.

"I can see where you are going with this. I was thinking of buying a CF liner both as reinforcement to the backs fabric and to waterproff it."

…the material is way strong enough, so I don't see the need for using a pack liner for reinforcement. I have used it to simply create a watertight space.

The other thing I would modify is to get rid of the bottom tie straps…I have never used these on any bag, every. I might simply snip mine off.

I have actually never used those straps either on any pack I owned (besides playing around with the load at home ofc).

skipping the CF liner and having it seam sealed sounds like a good idea then. What about this structual issue you wrote about – Think that could be fixed by adding an extra bar (which the loadlifter straps also could be attached too) to reduce that issue?

Hiya

I wouldn't say there is a structural issue…just a nuance that happens with many packs.

I have spoken to Joe about the prospect of a top bar, however, when I load my pack appropriately, any need for a top bar disappears….so does the need for load lifters.

I am still in the process of getting some input back from Zpacks about the fit of the Arc Blast pack I just got, but I walked around the house and took some photos to send them, and put 45 lbs of gallon water jugs, and then 35 lbs and carried it around to take photos and honestly didn't even put tension on the load lifters . . . don't really think I may even have needed to get them on this pack…but time will tell. My first impression of this pack is that it is a phenomenal pack. The pack felt perfectly balanced on my back, and didn't have any of the center-of-gravity issues that have come up in this thread as a possible downside. Honestly the frame in this thing may be a game changer (its a knee-jerk reflex, but having a light AND framed bag that also provides some ventilation is blowing my mind right now!)

Here is the obligatory photo of the pack (only loaded up with water jugs so it will not look very well packed)

Seth, it is hard to tell from photographs, but it sure does seem like the hip belt is significantly above your iliac crest.

Thanks for all the input so far. I'm thinking of buying one myself but I'm worried about figuring out the right size (I'm 6ft 4in tall)…

@ John – I know it looks high – but I have unusually high IC and find it works best to ride the hipbelt just about in line with my belly button. Based on that I'm wondering if I shouldn't have them go down an inch or two in the strap placement to compensate for that fact. . . I'll have to try it a few more times until I decide if I'm going to send it back.

I wear my pack high too at times and I tilt it back off my back because of an old injury. I've owned several zpacks blast backpacks, I was debating about whether to get the arc blast or a HMG 3400 southwest. The zpacks is lighter but maybe not as durable for bushwacking but I was thinking why not just get a 4 oz pack cover for bushwacking and save 13 oz. I like zpacks backpacks because they put the weight on my hips, comfortably; the stays are sewn in, anchored right where the hipbelts are also sewn on and this makes the pack feel like it has the load carry abilities of much heavier framesheets like the GG Nimbus, well maybe I'm going to far. I still have a Nimbus but unless I'm need to carry a lot of water I'm not going back. I have a 6 lb baseweight but frequently end up carrying about 18 lbs in my blast.

I have also owned an Osprey Atmos 50 and an Osprey Exos. I would never go back.

In the end I decided not to go with the ARC Blast but to get a Blast with straight stays. I'm thinking it will handle a bear canister better at the bottom of the pack, and less hassle with the hydration sleeve. I have no problem just tilting the blast back. Keep making those packs, Joe, we greatly appreciate it.

When I first go tthis pack I used it as a day pack, all the weight on the hips and shoulder straps loose just being used to stop it falling off backwards. The noise of the cuben fibre laminate rubbing on my shirt was irritating and I thought I may have made a mistake.

Did a two day 50km (30mile) bushwalk off track through thick scrub last weekend. The swishing noise dissappears when you have some weight in it, at least some weight is on your shoulders.

The pack was very comfortable, the temperatures were in the mid 20 degrees C (F?) and after a couple of steep scrambles I did get a bit sweaty on my back. The degree to which the arc can be induced into the frame is adjustable, I've noticed the more gear you pack in the less pronounced the gap and the arc in the carbon fibre stays – I might try exagerating the arc a bit more next time for more ventiliation.

The carbon fibre stays 'appear' to be quite vulnerable, what if I fell over backwards onto them and snapped one? The Blast had a nifty repair facility (sleeves you could slide over the frame members)- next time I order from Joe I'll ask for a spare stay – although this pack is supposed to operate without stays to some extent.

The stays do protrude above my shoulders a smidgen and I caught them on some overhead branches a few times – not sure how the optional extra satchel/day pack /pack lid bag they produce will sit on this pack? The mesh panel at the back was fine though – despite predictions all round it was bound to snag at every twig! I'm officially a Zpacks junky now – saving up for a quilt.

My Arc Blast arrived yesterday. Initial impressions are excellent. Did a quick load up and it's carries very, very similar to my exos46. Really happy with it and like all Joe's gear the design, usability and workmanship appears to be top shelf.

I'll report back after this weekend when I give it a proper field test.

I just got the note saying that my new Arc Blast has shipped. I had one I purchased originally a few weeks back, and determined with Matt's help (managing the store while Joe is hiking the NZ trail) that I needed about 1 1/2" lower for the shoulder strap attachment. While I sent it back, and had I new one made up — I decided to go ahead and have a few customizations added that I felt would enhance my use of the pack based on my previous pack usage over the last few years.

Here is what I did to the bag:

1) Buckle closure on the top strap and bottom 2 rear straps — if I use them I want to be able to quickly access them without having to loosen and pull to the side (for the top strap).

2) Removed the hydration port – never use it and even though I didn't tape the seams, having no hole with help with the rain resistance and occasional stream mishap.

3) Kept the Ice Axe straps and the Load Lifters (as the original one I ordered had), and kept the hippockets and left top pocket (for my cook set).

5) Had them put on SIDE closure buckles (like the ULA Circuit closure) instead of a top bag closure that comes standard, as I prefer to cinch the bag down to the sides (AND don't like to snag branches above me with a closure system on the top).

5) Tried to get button snaps instead of the velcro closure for the top opening – but was told that they didn't have any and we'd need to keep the velcro. Oh well, I just don't like a velcro closure on the top (snags my clothing when I reach into it) but I'll deal with it.

Photos will be posted once I have the bag and the time to post. I can't wait !