The Viper series uses Osprey’s Hydraform reservoir, which is the only rigid backed reservoir in the test. Add to that the semi-rigid Spacer vented back panel and you have a pack that has a distinct shape and feel on the back. You’ll either love it, or not.We’re in the not camp right now, preferring more suppleness from our packs.
If we run the Viper, it’s with a soft bladder, which sort of negates it as a purchase for us. The elasticated plastic lid lock for attaching your helmet to the bag is inspired and the quality of construction is probably the best in the test. The function of the hydraulic bladder is good with a fully adjustable bite valve and neat magnetic clip to attach it to the sternum strap. A well-appointed bag which, on paper, should win the test, however we’d suggest that you try an Osprey Talon 11 and buy a Camelbak or Hydrapak bladder.
This article was originally published in What Mountain Bike magazine.