Osprey Exos 46 and Osprey Exos 58 Packs

"Personally I say bugger all if you have good core strength"

I agree with Dan. Easier to buy a new pack, rather than get fit to carry the old one.

"Why not test v. an Aarn."

Probably because, your comments thus far to the contrary, we're not your marketing tool?

Great article Roger!
Something I noticed in your comparisons, which I have often seen talked about elsewhere, is the volume to weight ratio.

I've never been impressed by this statistic because I can picture a 100 liter gunny sack made from the lightest weight cuben, tied up with a dyneema string, suspended from ones neck. Extreme, I know, but it illustrates my point. That configuration would get a "great" score.

The statistic that would impress me would be the weight carrying capacity vs. the weight of the backpack itself. A backpack, in order to have a high weight carrying capacity needs a sturdy frame and formidable suspension – however – those things add weight to the pack.

The ultimate pack would be capable of carrying 40 lbs but weigh only 4 ounces. Weight carrying capacity to weight of pack, I believe, is the challenge in making an "efficient" pack. Not the volume to weight ratio: that's too easy!

I fully realize that the weight carrying capacity is a subjective measurement, but, obviously from your article, so is a volume measurement. As long as the same person is rating the weight carrying capacity of a series of packs, like your excellent article could, the measurement could at least be "accurate" relative from one pack to another.

"As a result of these articles I am beginning to become a fan of the Lightwave series of packs, and especially their split hipbelts. I'll have to find a US vendor so I can try the largest one on with weight."

I'd support that – I've always been impressed by Crux. From 2001 to 2006 I travelled to London regularly and checked out the Crux packs and was suitably impressed. Lightwave came along later. Oddly, when I was living in London in 2006/2007 Lightwave was almost impossible to get my hands on – they seemed to have very limited dealers.

Hi EJ

It's not meant to be a secret, and this is a good place to point it out. many folks shy away from the mesh backed packs for winter use, but at least in the case of the Exos, that mesh space can be well utilised. In winter I put my hydration bladder there with a thin piece of evazote between it and my back. this keeps out snow, keeps the cold water off my back, yet also keeps the water from freezing. It adds around an extra 3 litres of usable volume as well, which also comes in handy on winter trips, and it's easier to get your bladder in and out of this space than the internal hydration sleeve. other stuff like rain jacket, wind layers, ground sheets etc…could also be put there if you prefer to carry your water in bottles. It is all these little extrs that make the Exos 58 (really a 61 in large, but who know what the true main pack volume is) a suitable winter pack for me. Generous top pocket, generous hipbelt pockets, generous side pockets and a generous kangaroo pocket for sleeping mat, sit pad etc…just don't try bushbashing in this configuration or something is going to get shredded!

Bending at the waist doesn't seem to affect Lance Armstrong's performance terribly. Sure he would probably perform better on a recumbent bicycle, but it's clear that athletes can perform for many hours at very high levels of exertion with extreme bending at the waist.

Hi Roger,

The research compared an Aarn Bodypack with a Karimor Alpiniste internal frame pack – state of the art at the time- not an A Frame! Are A frames still available?

The picture shows you with quite a bit of forward lean. Forward lean is least when standing still as in your picture, greater when walking forward, and maximum when climbing. (The same is true without any load).

Trunk angle does not measure forward bend at the waist as you suggest, but the difference between a line drawn between the shoulders and the hips- and the HORIZONTAL. So bending forward at the ankles with a straight back is an economical posture to assume with the forward lean. As most of the subjects in the study were experienced backpack users, I assumed they also leaned forward in this way, but this could be checked with the original research photos.

Ray Lloyd, who did the original pioneering research on forward lean, has been doing some more work on load carriage. He recently wrote regarding his latest work: I quote "my current work seems to suggest that freedom of movement of the trunk is a determinant of economy (your double pack system allows more than either a backpack (which constrains to lean forward) or head-loading (which constrains to upright). In addition, our current findings suggest that individual variability of response in relation to economy is greater than we might have anticipated. Consequently we are intending to look at relationships between economy and kinematics at a range of loads and speeds and wondered if you might be interested in having some of your more recent designs tested in this context and, if so, if you would be able to send a sample(s)".

If you want to contact Ray his details are below:

Ray Lloyd
Head of School
School of Social & Health Sciences
Level 5 Kydd Building
University of Abertay Dundee
Dundee
DD1 1HG
Scotland

"If there are other factors coming into play, such as the ability to see one's feet, than any small benefit from a shift forwards of the CoG due having front packs in place may *in practice* be inconsequential. This seems to be the experience of many walkers: they rate being able to see their feet far higher, especially in rough terrain.

Other factors which can detract from the front-mounted load include the increased heat load on the body from the reduction in ventilation, the increased difficulties experienced in swinging a pack on and off one's shoulders when there are large weights on the shoulder straps, and the increased problems when scrambling with a bulky thing at the front pushing you off the face. The importance of these factors will depend very much on the individual and what he is doing."

+1 to all of the above. However, Aarn packs used without the front pockets work very well too. It's mainly the lack of a hydration port that stops me from using them in this way…yet another factor important to *some* walkers.

Hi Alan

> Do you still think your external frame sacks are a lot better than commercial
> internal frame ones.
Let's say I still prefer my external frame pack for most conditions. It is very light, the harness suits me very well, and it handles anything between 8 kg and 28 kg happily. yes, I am able to carry up to 28 kg with it when portering in to a remote hut for a ski trip. I can't normally get that much capacity with the IF packs.

However, it does have one disadvantage. The frame is very light and could be damaged if mistreated. I package it up in a cardboard box every time I fly. If you are planning on flying and don't have a high load, an IF pack might be a safer (less worry) choice.

> Doesn't the front rucksack cause overheating
I found that it did on me, at least in an Australian summer. Perhaps I am a bit sensitive to this, as I normally travel with very light clothing.

Cheers

Hi Coin

Sorry, but I don't have a simple answer for you. I think I noted somewhere in the review that my hips are rather narrow, such that many hip belts do not work very well on me. For this reason I have always preferred to carry the load on my back. This does *not* mean 'on my shoulders'.

With my design I find the load does go through the mesh on the back of the pack to the full area of my back. Frankly, I am not really sure why this works so well, but it does work for me.

I am sure that it won't work for many other people, and that a solid hip belt will work better for them. In this sense, fitting a pack to a person is very much like fitting a pair of shoes. I sigh (for the same reason) when I see someone ask 'what shoes should I buy' and then read a reply that they should buy SuperDucksMultiWeb shoes.

However … I will offer the following advice – which is also in the Review somewhere. Try to buy a pack which matches your torso length, but do not buy a pack with a torso length which is too short. Better to have a pack torso length slightly longer than your torso length: that will throw the load onto your hips more effectively.

Even better: pick a pack in the right size with an adjustable torso length. Then fine tune over several trips how it fits you. Yes, I definitely give brownie points to packs with an adjustable torso length.

I also give brownie points to packs with a solid stiff harness or frame. Frameless packs are all very well if my total load is under 6 -8 kg. Over that the weight of the harness is far outweighed by the added comfort it brings. Now, I know this comment will attract numerous responses contradicting me and saying how wonderful a frameless pack is. Well, as with shoes …

Can an external frame pack (like mine) stand up the 'heavy brush'? Chuckle. Trust me, the scrub in the Australian Blue Mountains (and in SW Tasmania) is definitely world class.

A commercial equivalent? Sorry – at this stage I cannot make a recommendation, because I don't know.

Cheers

Roger (Caffin):
Would any of the ultralight small manufacturers be interested in making your external frame sacks.

The osprey atmos 50/65 has a kind of all back mesh (for ventilation) but I think the gap between back and pack is bigger. I didnt like the shooulder straps.

Roger (Caffin):

Actually, from reviews, the osprey exos 46/58 looks better than the atmos, as still has kind of all back mesh (for ventilation) but the gap between back and pack seems smaller, and the rucsac storage looks less curved.

Perhaps you could borrow one and compare it (not using waist belt) against your external frame pack.

Hi Alan

The survey covered both the Exos 46 and the Exos 58. Nice packs.

Cheers