Reviews Deuter Hydro 2.5 water pack Drink up, the world's about to end! Photo: © Cyclingnews Along with baby brother the Hydro 1.5, the Hydro 2.5 is Deuter's first entry into the back-mounted 'drinking system' area, a product category that's immensely popular with mountain bikers who often find themselves a long way from an easy bottle refill. This German manufacturer is known for its inexpensive but decent quality rucksacks and has been making bike bags for a few years now, including some very functional waterproof panniers in conjunction with Ortleib. The two packs differ in size and number of compartments, but share the same main feature, a pair of raised ridges that sit against your back to help you keep cool. Deuter calls these 'Airstripes', and each one is made up of rounded foam blocks overlaid with mesh, so that there's room for air to flow through the ridges themselves as well as between them. Convenient tube exit Photo: © Cyclingnews Other features include mesh shoulder straps, a waist belt and sternum strap, insulated bladder compartment, and exit channels for the drinking tube through both shoulder straps. The Hydro 2.5 has a large outer pocket, plus a pleated 'floating' pocket held in place with an elastic cord that also provides a place to carry your helmet off the bike or a bulky weatherproof item like a jacket. The 1.5 has one medium-sized, flat outer pocket. Two bladders are available, in 1.5 litre and 2.5 litre sizes, but both packs will take the larger bladder, and there are Velcro loops inside them to hold the bladder up as it empties. The 2.5 litre bladders actually hold 2.6 litres if you fill them carefully. Double action mouthpiece Photo: © Cyclingnews The mouthpiece consists of a standard bite valve that resembles an early Camelbak valve, mounted on a pull tap like the top of a water bottle. It's therefore possible to close the valve completely if, say, you're carrying the pack in the car and don't want to risk it accidentally being opened. Hanging on by a thread Photo: © Cyclingnews The drinking tube mounts on the bladder by a threaded connector so it can be removed for cleaning. The bladder cap is also threaded, but there's no tether to stop it going astray. On the trail We found the compartments on the Hydro 2.5 easily swallowed a typical stash of ride junk: tubes, tools, mini-pump and food. On your back, it's a very comfortable and stable pack, which is helped by the broad shoulder straps and the sternum straps, plus the elastic holding everything snug in back. The Airstripes seem to do what they're intended to. My shirt was substantially less soggy at the end of a three hour ride on a warm day than with my usual water pack and the mesh straps also noticeably increase ventilation at the shoulders. More would be better Photo: © Cyclingnews On the downside, the mouthpiece releases water more slowly than some. A Blackburn valve, for example, lets water out twice as quickly as the Deuter (30 seconds/litre against 65 sec/l in a simple gravity-powered test). Deuter's bite valve is 'good enough', but it could be better. Long zips make the pockets easy to get into when you need your stuff, but the outer pocket uses a vertically aligned zip, and that's a bit of a worry; leave it open and things fall out. It's also the zip most likely to get muddy, so it's good to see a cover to protect it against the ingress of crud. Overall This is a very comfortable and practical pack, especially in hot conditions when the Airstripes really come into their own. A higher-flow mouthpiece and better placement of the outer pocket zip would be improvements, but neither is a show-stopper. Pro: Comfortable, stable and well-ventilated water pack Con: Mouthpiece flow could be better; bladder cap needs a tether More information: Deuter's website Cyclingnews Rating: What do you think of the Hydro 2.5 or any other water pack? Let us know November 2 tech features, news and letters News: Cannondale posts loss, Nirve hires ex-GT designer Reviews: Speedplay Zero pedal, Deuter Hydro 2.5 water pack Letters: Wheels — Light, strong, cheap?, Campagnolo steel, The 10.5lb bike, An even lighter bike, Bike weight Got tech? Send news, comments, press releases and questions to the Cyclingnews tech-heads Index to tech features