Zpacks Arc Blast

I think I've gotten enough miles on this pack to write up a worthy review.  I'll start off by saying I absolutely love this thing!  I ordered an Arc Blast from Zpacks.com when I got tired of carrying several days worth of food in my frameless MLD Burn.  While I really like the Burn, I missed the support of a frame for heavier loads (more than 20 lbs).  I didn't want to revert back to the relatively "heavy" Osprey Exos 46 however.  There is a newer version, the Exos 48 which is weighs in at 2.6 lbs - excellent for a mainstream company.  Still, I didn't want to buy another (nearly identical) pack to save just a couple of ounces.

On the Hammersley Wild hike, Chris carried a Zpacks backpack - and after the Sufferfest I decided to check them out.  The price is steep, but all high end ultralight gear is.  And the base weight is only 16.5 ounces (52 liter version)!!!

Matt was extremely helpful and responsive when placing my order.  You gotta love the ultralight cottage industry community - where else can you communicate directly with the people making your gear?  Despite being in the middle of their heavy order season, they got it out to me in just a couple of weeks.  Finally, a pack customized to fit my 6' 5" torso!  You can't get that with an Osprey back.

Arc Blast details from Zpacks.com:

45L Pack Size:
Total Volume: 45 Liters / 2,750 cubic inches - 16.0 ounces (454 grams), $275
Body dimensions: 5.5" x 12.5" x 30"  (14 cm x 31.8 cm x 76 cm)

52L Pack Size (the original default size):
Total Volume: 52 Liters / 3,200 cubic inches - 16.5 ounces (468 grams), $279
Body dimensions: 6.5" x 12.5" x 30"  (16.5 cm x 31.8 cm x 76 cm)

60L Pack Size:
Total Volume: 60 Liters / 3,650 cubic inches - 17.0 ounces (482 grams), $289
Body dimensions: 7.5" x 12.5" x 30"  (19 cm x 31.8 cm x 76 cm)

Pockets:
The side pockets account for 5 Liters / 300 cubic inches and the mesh center pocket is 8 Liters / 500 cubic inches, and are included in the total volume.

I purchased the 52 liter.  Coincidentally, frequent hiking buddy GQ also got the Arc Blast about a week before me!  I also chose to add on the hip pockets (removable), bottle holder (attaches to chest strap, also removable), ice tool holders, and trekking pole holders.  The total weight, with my additions, came to 19 ounces.

This is the lightest back with a frame I have every seen.  This feat is accomplished by building the pack out of light weight denier reinforced cuben fiber, using carbon fiber for the frame, and leaving off the countless unnecessary buckles, straps, and extras found on mainstream packs.

You can choose your torso length (huge selling factor for me), belt length, and color (they have several options, including camo!).  You can also choose to leave off some options, like the frame or hydration port if you don't want them.  All this can be customized right on the site, which is very cool and easy.  Definitely go check out the site - they have tons of pics of all the different configurations.

The packs stand up pretty well, unlike frameless packs.

Toughness

Early versions of Zpacks were pure Cuben Fiber - but the new Arc Blast is a hybrid Cuben plus denier polyester protective coating.  I was nervous at first about the durability - but so far that feeling has proven unfounded.  The only hole in mine came from getting my bottle holder snagged on a branch while navigating tight summit trails in the ADK's.  Nothing a small square of Gorilla Tape couldn't fix.




GQ reported that he started to see some wear on the very bottom of his pack from sliding down rock scrambles (LOTS of them), presumably.  He preemptively applied some tape and all was well.  I haven't noticed this problem with mine, but intend to keep an eye on it.

I put it through any number of stress tests over the last year or so I've had it, including a couple of packraft trips.

I was worried that I'd find some wear marks from the paddle edges, or that the hard jostling run might pull some shoulder strap threads.  My fears were completely unwarranted, as it come through unscathed.

Features and Accesories

It's rainproof!  I'd almost go so far as to say, if you sealed up the hydration port, you could fully submerge it and come through with dry gear.  I haven't tried that yet - but I have experienced a full-on deluge that took me from sweltering to near-hypothermic in minutes.  This was after 12 hours of my sweaty back contacting the bottom of my pack where my quilt was.  One or the other (or the combination) managed to get the barest amount of moisture on the surface of the quilt.  But I mean really minor.  And only at the very bottom of the pack, maybe 10 square inches.

I didn't have it in a dry bag like I usually do (generally a bad idea, but I wanted to see what would happen).  Knowing the shear volume of water that was dumped on me, I call this an incredible achievement in water-proofness.  If you use a light dry bag like Sea to Summit's Ultra-Sil Nano inside your bag, or garbage bag liner (as you really should for any trip to be sure your down-goodness stays dry) - you will be good to go.

Quick aside - I actually stopped using garbage compactor bags a year or so ago.  I had a hard time finding them cheap, and was constantly tearing them.  The Ultra-Sil bags are of comparable weight, but you have a secure closure in case your bag actually is submerged.  It's nice to guarantee dry gear.  Just my 2 cents.

GQ did a shower test - putting the pack in the shower for 30 minutes.  The insides came through dry.

The top has a dry bag-like roll up and buckle snap closure.  The top seam also has velcro, making it easy to align the edges when rolling them down, giving you a nice solid rain proof seal.  It works very well.  It also lets you tighten down the pack to fit small loads.

The optional hip pockets are also rain-proof.  I have the older style, that close with a flap and velcro.  The newer versions are your standard taped zipper style.  Both are quite generous in size.

The back rest is a suspending mesh panel.  You can adjust the arc by tightening or loosening a pair of line-locks at the top by your shoulders.  Mine seem to always work there way loose eventually.

On the sides you have some reflective line for securing stuff above or in our bottle holders.  The bottle holders on each side (with you can optionally leave off) are quite ample - holding a 32 or 40 bottle.  The tops have shock cord woven in to give you some retention.  It's not quite as secure as some other packs I've had, yet I've only tossed my bottles a couple of times (during nasty ski spills!).    They stay put just find on scrambles and ballistic movements.



You will find a long list of accessories and mods are Zpack's site - so I won't bother to list them here.  But it's nice that they easily give you the option to customize your pack exactly to your needs and wants.


Conclusions

With many, many miles on it already, I'm confident this pack will last a very long time.  My only regret is not getting the 60 liter version for winter expeditions.  But really, I might only have trip or two a year that need that kind of capacity.  The rest of the year I'll barely fill three quarters of the pack.

While pricey, the Arc Blast is more than worth it to have a pack that fits me like a glove.  The incredible base weight and other features are a bonus.  Zpacks customer service is great, and very responsive.  I have no reservations about recommending them or their gear.

A long with my Arc Blast, I ordered a set of Zpack's rain gear.  Rain jacket, kilt, and mitts - all in Cuben.  The kilt has gotten the most use, it's perfect for 3-season rain showers!

One method for dealing with oppressive heat during a rainstorm!