If you haven't heard of Wingnut hydration packs yet then you soon will as they are, without doubt, the best fitting packs available. The Wingnut concept is to keep loads mounted low, letting the hips take the weight. This means the bag looks a bit different to normal hydration packs, which traditionally make use of the space between your shoulder blades.
The Splitback gained the title 'cock and ball bag' because that's what it looks like, but the simple design is a winning one. A single 580cu/in compartment can be accessed three ways. Firstly, through the full-length waterproof vertical zip - ideal for packing and unloading at stops - and also via left and right waterproof zips positioned on top of the wings - or 'balls' as they are affectionately known. These side zips allowed access onthe move and, providing you've packed carefully, you usually put your hand on the thing you're after.
We're still amazed how little lateral load shifting occurs with the Splitback. Even thundering down steep descents the pack never once tried to slide up our backs and into the back of our helmets - something most other hydration packs certainly do. It'll take a three-litre bladder (not included) in a separate inner sleeve and there is hose routing for left and right hose feed.
Given the stripped down, essentially detail free nature of the Splitback, it weighs next to nowt - one reason they're favoured by weight-conscious marathon riders and those madcap 'adventure racers'. How much do I like using it? You will literally have to wrestle this bag from my cold dead hands.