I really like this pack... It takes a few tries to figure out the best position for comfort and weight distribution (as with most lumbar packs). I am 5-7 140ish and have fouund it to be comfortable even when full. I bought it for use while dirt bike riding, but I use it all of the time (hiking/walking, soccer practice, even at the park with my kids). It has a good amount of storage and it even works to just sling across shoulder when not doing major activity. The only down sides I find (1)pulling out drink tube long enough to get to mouth and then getting it back without having a lot of tube sticking out (2)the straps hang loose when the belt is pulled tight around my waist

I use the pack for my long runs as I am training for my first marathon. It rides on my low back with a very comfortable feel. I have filled it up with 40oz. of liquid, several GU packs, cell phone, house keys and some small items with no problems. Easy to tighten and drink from. Would highly recommend it to anyone.

The capacity for this device is just right for longer runs 5 to 10 miles.

I'm a little large (6 ft, about 220 lbs.)and need the hydration.

I used it on a Bartram Trail race (8 miles at 3500 ft. elevation) in NC just two weeks ago.

I fumbled with side/cinch straps a little, but eventually figured out how to best use them.

It's a good size, but takes getting used to running with a lumbar pack with that much water volume.

I think this one is best for fitness walkers and day hikers.

It can work for trail runners, but you need to be a decent size (min. 5 ft. 10 in.)and have the strength to carry that much weight (roughly 4 pounds filled) at your center of gravity.

If your smaller than the min., I recommend a smaller volume lumber pack or go with a over the shoulders type hydration pack.

I'm 5'2" and about 110 lbs. and I used this pack for a 15.5 mile hike/run and it worked out great for me. I would recommend this pack for anyone, no matter what your size is!

I bought it for marathon training. I already have a Camelbak Catalyst but needed a higher capacity for longer runs (45 oz vs. 28 oz. or 18-20 miles vs 13 miles for me). I'm definitely biased as I prefer Camelbaks over water bottles! The FlashFlo reservoir is way easier to fill and put back into the pack than the Catalyst. The belt tightens in front - another improvement for ease of use. The side-cinch compression system allows one to tighten it as you drink to reduce the annoying sloshing and help keep it from riding around. Two, more than ample zipper pockets for gels, keys, etc. The outer pocket is designed to hold a CD or MP3 player but I don't run with music so I've never tried that feature. It took me two runs to get accustomed to the adjustments. I kept prematurely tightening the side cinches at first which causes the pack to twist upside down. It also took some time to figure out where to let it ride on my back comfortably. I wouldn't recommend it for small people as the filled reservoir weighs nearly 4 pounds. (I weigh nearly 200 lbs.) Once I figured out how to adjust it for my comfort, I really fell in love with it.

I bought this pack for marathon training and have liked it for that purpose. Its best feature is probably the stable ride. I have found it comfortable over long runs, and the side compression straps allow me to keep it stable as the volume decreases (from drinking). It also has plenty of room for keys, a few gels, and a light windbreaker. The tube is adjustable (just cut to length), easy to drink from, and doesn't drip. Overall, this is a good running hydration solution.