GROUPTEST HYDRATION PACKS

We cram nine of the latest medium-sized biking backpacks with kit and water, then hit the trails to see what spills out

Hydration packs have fallen in and out of fashion over the years, but for riders straying a bit further from the beaten track, they've always been a practical way to carry everything you need for a big day out in the hills.

The medium-sized packs we have on test, with a capacity of between 3.51 and 111, can fit a modest selection of tools, a mini pump. spares, a capable waterproof and maybe even a light insulated jacket for those unforeseen mechanicals in cold weather. Add to that the equivalent of three large water bottles or more and you can see how they cover a lot of trail eventualities, from hot day-long slogs to exposed winter rides.

To survive and thrive in these conditions, they foremost need to be tough, with hardy fabrics and quality buckles and closures. We've often seen packs binned purely because the zips get gritty and fail. They also have to be comfortable to wear once loaded, so need a stable but unobtrusive harness system to keep things under control should the riding get lumpy. Look for a ventilated back, to prevent sweat build-up on sticky summer rides. Finally, you want to be able to access the contents in a hurry without tipping the lot onto the trail, so organiser pockets should be considered essential.

During our testing, we packed all the packs with kit and then pulled it out on the trail to see how easy it would be to access the small stuff. We took them on long days, to see how comfortable they were in real-world conditions, and we hit the trails hard, to feel out any instability or poor design. If they didn't come with a reservoir, we subbed in a 21 HydraPak bladder to check their hydration capability.