I've been using the pack for a few times now for my long runs, and love the fact it doesn't bounce at all. The pack fits snug without feeling uncomfortably tight. It sits very high on the back, and comes down to my mid-back level. It really doesn't bounce, even in steep downhill sections, although you could hear the reservoir sloshing a bit when it's half empty (but it never bothered me).Pocket-wise, I use the 2 front fixed pockets for bloks and mixed drinks (a 500mL bottle fits nicely in one of the pocket), and use the 2 side zippered pockets for longer term food storage. I am reasonably flexible but the 2 side pockets cannot be reached by hands unless I take the pack off. I never used the 2 velcro/removable pockets - they are really useless, not big enough for any smartphone (maybe just for keys) and are heavy. The Salomon designers really missed the mark on this one, as there is no convenient way to stash the phone without it bouncing around. The main vertical pocket on the back is big enough to put a sandwich and a very light jacket. Then there is an inner pocket in the back with magnetic-closure - it's innovative but it's not a secure storage place - I use it to store some TP for emergency.The reservoir is enclosed in a semi-stiff reflective sleeve - it did well to keep my water cool from the generated body heat on my runs. The sleeve is super light, and makes it very easy to put the bladder in the pack. I really like the quick disconnect of the bladder hose - since the hose is tightly routed along the pack, it's nice not having to take out the hose all the time when drying the bladder. The hose is routed from the bottom upwards, and I thread the bite valve through one of the numerous elastic attach points so that the hose doesn't bounce, and I don't need to take the mouth piece out to take a drink.It's a fully featured pack, complete with hiking pole attachments and a whistle, but I haven't used any of that yet. But even with all the bells and whistles, the weight feels very reasonable. I don't notice it at all. The pack fits me very nicely - I'm 110LB and 5'6. I would expect the XS/SM size fit someone a bit bigger but not much more. The bigger guys should consider the Salomon skin pro 3 packs, as even the M/L size in this pack barely fits my other half who's on the skinny side. Finally, my runs have been in the mid-60's with strong sun but cool occasional breeze. The pack felt ventilated - I didn't have a huge wet spot on my back and even though the pack felt wet, it wasn't drenched.I'd highly recommend this pack. It's well thought of (other than the iPhone issue), obviously was designed for runners by runners. It's a tidy little package that doesn't have all the extra straps and thingies dangling around found so frequently on other running packs such as Nathan or Camelbak. It makes you look fast, and best of all, it doesn't bounce.
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