Leonidas13I cant say how accurate my scale is, but it weighed the Graviton 38 at 2.4lbs, and without the brain it was 2.2lbs. The brain is so light I doubt you'll notice its on or off when wearing it.
Leonidas13If being ultralight is the goal then that might be a good idea. But for me Graviton's features and versatility make it well worth it, and its already very light as well.
lha_lukePart of the conundrum is I already have a similar size pack that weighs 40oz. The issue is that it causes serious back sweat so I was looking for something that would negate that as much as possible. There are only maybe 3-4 options to combat this:
ZPacks Arc Blast 52L 21oz $335
Osprey Exos 38L 34.2oz $130-160
Marmot Graviton 38L 38oz $120
Sierra Designs Flex Capacitor 42-60L 42oz $200
The first three are pretty similar on how the back frame works to reduce hot spots where the Skurka flex looks like it would have 3. ZPacks is of course the lightest and most expensive and if I LD backpacked more than once a year it would be my choice. The Osprey is next lightest and can be dropped to ~30oz , has the lifetime warranty and I can try it on local to get the fit dialed in. Marmot has some unique features but my concern is the lack of adjustability, it will either fit or it wont.
Leonidas13Hmm yeah I haven't hiked in the summer with the Graviton yet just winter hikes here in Washington. But I have in my Osprey Atmos 50L which has a lot of mesh venting on the back, i think more than the Graviton. I still got a lot of back sweat going but the venting still helps a ton. That's a tough choice!
Leonidas13Granite Gear has the Leopard VC 46 pack which has what they call the Vapor Current Suspension (Same as Crown 60) with a 35 lb Load Rating. Lifetime warranty, with most of their packs coming in either different sizes or adjustable to sizes.
compatible with vapor current airbeam frame (pg 10)
2lbs, 6 oz 1.07Kg With Frame Removed (25lb Load)
2lbs, 9oz with Klymit VC Frame (35lb Load)
Granite Gear also has a Crown VC which is larger, 60L.
I have never used a ZPacks Arc Blast, but did try one on at the PCT KickOff a few years ago. It does hold the pack a good bit away from your back. The only thing to be aware of is that by holding the pack off your back it will then allow the weight to swing about a bit if you have a tendency to sway side-to-side. I liked the feel of it and have a problem with getting too hot also. It might help.
You might check out Erik the Black's listing of every light weight backpack he could find.
It's at
http://blackwoodspress.com/blog/28703/ultimate-guide-lightweight-backpacks/
He did the same thing for pads, sleeping bags/quilts, and shelters. It's updated as people give comments.
Leonidas13ive got the osprey exos 48 and after two seasons i'm actually considering getting this pack now. really miss having a bottom access for my pack, so much so that i think the 4oz is worth it for me :)
alexiconI actually ended up going a whole different direction. The weights were so close unless I went ZPacks that I ended up going for weight over the back arc. Found a Granite Gear Virga 2.
54L 19 oz $118.