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Sure, that emergency snake-bite kit you have is pretty rad. But during your mountain-bike ride, chances are good you’re going to need access to water, an extra layer, and a tire repair patch long before you’ll have to tend to a set of thin puncture wounds on your calf. With the super-comfortable Osprey Viper 13 Hydration Pack on your back, you’ll be able to tote along the day’s essentials and even have some room left over for less-crucial items, like anti-venom.

  • HydraForm reservoir is made with BPA- and PVC-free materials and features a design that squeezes your water supply for easier drinking
  • SpacerMesh back panel provides super-light cushioning for a comfortable fit
  • BioStretch shoulder harness system features mesh-covered foam for superior comfort and small sleeves to hold your energy gel pouches
  • LidLock helmet clip feature allows you to attach your bike helmet to your pack for hands-free storage.
  • Wide variety of organizational pockets keep your tire pump, patch kit, and multi tool in place
  • Side compression straps reduce pack volume if you’re carrying a smaller load
  • Reflective detailing on front panel and a blinker-light attachment loop help keep you visible

  • Reviews
  • Q & A

What do you think about this product?

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My ultra light mountain running pack!

  • Familiarity:I've put it through the wringer

Osprey has one of the best bite valve for hydration, so that's why I bought it. With one hiking season under it's belt, I'm very satisfied with this product. I use it for Mountain trail running in the White Mountains of New Hampshire, lots of elevation gain/loss. I need to travel fast to complete 20-25 mountain miles in a day. I bring 5 liters of water, two cameras, trail bars and couscous with a mini rocket stove. So, the pack has sufficient room, yet it allows me the body movements I need to run over boulders and scree without throwing me off balance. I love this pack!

Great mountain bike pack

  • Familiarity:I've put it through the wringer

This pack is a great size for long rides. When I'm going for longer than I have room to put all my water, food, gear in my jersey, I go for this pack. The hydration reservoir is easy to fill since it has a rigid support on it and the bite valve won't leak. The magnetic attachment keeps it within easy reach. Its got enough storage to carry food, tools extra layers and sunglasses. The helmet attachment is slick and easy to use.

The straps adjust easy and hold it snugly so its comfortable to ride with and doesn't move around. All in all a great choice for bike hydration.

I take this pack on all my adventures!

  • Familiarity:I've put it through the wringer

I've had this pack for a couple years now. Its compact enough to take on any activity. I use it for cycling, canyoneering, as a daypack hiking, it is very versatile. This pack is what got me hooked on Osprey. I love the helmet feature a ton and love that Osprey is starting to make that feature a standard on their packs.

I take this pack on all my adventures!

Love it!

  • Familiarity:I've put it through the wringer

This is a great Hydration pack!

I have had about a million, it seems, of different hydro pack over the years, especially in the Army. This pack might be the best one i have ever own( for the money), its super lightweight, but that can all change depending on what you pack in in, it has a ton of room and deep pockets, that you can pretty much pack for an entire day. You also have the ability to expand the width of the entire pack with a few adjustments, i can put a jacket back there no problem. when you don't need to much you can wrench it all down and it becomes pretty compact.

The bladder section might be the best part about it, it doesn't look like it holds a 100 ounces but it does. It also has the this ridged "back bone" to the bladder making it very comfy on your back as it contours to your body. it also prevents water from sholshing all around and keep the bladder in place, no matter what you are doing.

Worth the money by a long shot.

You make a great point that I think some/many overlook: the adjustability of these packs! They can also be cinched down when not fully loaded. It really is better to have a slightly 'larger' pack, and have the available room, but also have the option of tightening it back down when not needed.

The Genius of Osprey!


    I absolutely love this pack. The hydration system that comes with this pack is excellent. The magnetic retention contraption on the hose and sternum strap is a feature that I cannot live without. In fact, I have bought the magnet pieces for all of my packs. The pack's best feature in my opinion is the ability to expand it and stuff a jacket or layer in it once things heat up. I do a far amount of technical riding and I have never had the pack's weight to shift and cause me to lose balance. It just seems to stay in place.

    what are the differences between the viper 13 and the raptor 14?

    Hey Frederick,

    Great question! The Viper series is slightly lighter, and has a simpler hip belt. The Raptor series features zippered low profile pockets on the hipbelt for a shot of gu, lip balm, etc. The Raptor also include a sweet removable tool pouch, which the Viper does not have. When I train sales staff, I express that the Viper is a "detuned" Raptor, valid as a choice because of its weight, simplicity and price. The Raptor is more feature rich. Both offer the same reservoir.

    Hope that helps!


    Osprey Rep