hi

I've been looking at getting a new rucksack and was wondering what the benifits and drawbacks are to the Air Flow system than I find on a few bags out there..

as far as I can see it's to stop your back from sweating as you walk.. does it help any with the weight load? and what about packing? is it harder due to the shape?

or is this style of back design superior to the older design where the bag rested against you're back and sweat pourd down your trouser legs?

thanks for any input

I couldn't say it better than Jon in his article this month!

Personally, I have an airflow style (Asolo branded, bought in Canada) for summer and casual use - occasionally I run in it too -and a classic simple form rucksack for climbing and winter walking when I need to hold the weight closer to the body.

They definitely help the sweat problem, but at the expense of stability and ease of packing.

As far as I can see it's to stop your back from sweating as you walk.


That's the only real reason.

does it help any with the weight load?

Well think about it in terms of shifting the centre of gravity of the sack a couple of inches further back. In order to maintain the air gap the back system of the rucksack ends up quite stiff. This does mean that small sacks tend to be stiffer and thus more stable than comparably sized sacks.

and what about packing? is it harder due to the shape?

Possibly marginally although the shape isn't too distorted. Because the contents of the sack are kept off the back then you won't find something badly packed digging into your back.

I've tried it ('til it broke) and then went back to my old pack. I've just bought the Osprey Talon 33 to try to reduce my weight further, I'm awaiting seeing if the 1kg+ I've saved will reduce my sweating.

Go for comfort 1st. Then go for comfort.
A merino base layer will help with 'sweaty back' syndrome.

The additional thing you have to remember with shifting the weight distribution is what is known as the "moment of inertia". As well as moving the centre of mass somewhat backwards (which makes it harder to support heavy loads as you pass more force to the shoulders) it also increases your MoI in your yaw & pitch axes.

Trying to explain that out of the context of engineering language, it essentially becomes more difficult to rotate your trunk about your spine and to tilt your torso about your hips. This means that you lose agility and will exert more energy in manoeuvring - equivalently that your pack will resist being swung around and hence will apply more force to your hips and shoulders when you turn.

If you need to illustrate what I mean, then stand upright with your arms crossed over your chest and then rotate your trunk with your feet and legs firm on the ground. Then do the same movement with your arms outstretched to the sides. You will be able to feel the additional forces required to accelerate your body whilst your centre of mass has moved very little in these two configurations.

Cutting to the chase, I would say that vented back systems are great for general summer hiking when you will sweat from the heat and exertion, but don't fare so well if you need to be manoeuvrable. They are also OK for casual running on the straight and flat (I use mine for carrying my office clothes and paraphernalia if I decide to jog to work) but wouldn’t make great packs for trail/adventure racing IMO.

John

I had one, found it great for summer day walks but I found it unbalanced me on scrambles.

Gave it away in the end cos I never used it.

i find them uncomfortable and also irritating trying to find something in the bottom of the pack. in summer i sweat on my back anyway - the type of sack doesn't matter. the mesh allowed a bit more air to it but it certainly didn't give me a dry back. a good wicking quick drying top works wonders for summer (note merino doesn't wick nor dry quickly). take sack off and 5 minutes later a dry back.

Parky,
mine has a separate lower and upper compartment so access isn't bad - and it does seem to help the damp back quite a lot. I suspect it depends on the design. Mine is an Asolo Aero 25 but actually it is not really the same as the Asolo brand known in Europe for boots etc. They have a licensing agreement with another manufacturer in Canada making packs, tents etc. but (IMO) at a lower quality & price range. Still, it does the job and I'm not complaining! Good value stuff if you are ever needing replacement kit in Canada.

they look interesting john.
my own gripe with them is that the mesh always digs in my lower back..or in the case of osprey, other bits dig in too. serves me right for being a weird shape.

"merino doesn't wick or dry quickly."
I never get a chilled back with a merino base layer but have done with a synthetic.

Blessed is the merino fairy. She vists at night and spins her lovely web across the gates and gaps in hedges of the fields in New Zealand. The sheep, when heading out to the fields walk through these gaps where they become entangled in the webs. Later on the webs are removed by the farmers and later made into the yarn.
Everybody is happy, the farmer, the sheep, you and me and of course the little merino fairy.

Night night boys and girls.

I take it there must be wi-fi in the pub ptc*?
Brilliant.

lol ptc.

i've never had a chilled back in summer too mike.

especially without a wind tunnel across my back ;-)

but i take the point with the gap there on chilly summer days.

might see if I can pick up a second hand one from E-bay then,, try it out before I go and get a new one..

thanks all :)

good idea robin. you'll be able to test it under lots of different conditions then.

<mutters - wish i could think of sensible things like that more often>

I have the 30ltr,35ltr,50ltr bergahus airflow back systems sacks and i must say that i love them to bits,
keeps a nice flow of cool air constanly between you and your shell layer on a wet day helping sweat escape more easily and up your back and out your collar...
must say i have never recalled having a wet back as yet while using them,
but when i use the 65 Bio Flex i can instanly feel my back getting clammy and damp,not too the point where im unconfortable but just noticable..

if its a dry back you want i would definatley give these a try..but thats just my opinion..

good luck in your hunt for the perfect sack!!