Keeping well hydrated is essential for the cyclist; you can easily require over 1/2 a litre of water per hour - often more.
Perfect for off-road riding, leisure riding and adventure sports hydration packs are an easy way to provide hands free hydration as well as giving you somewhere to carry waterproof, spares and food. A huge variety of size and style are on offer from the slim and lightweight designed for racing and short trips to the all-day adventure pack, which allows you to carry several litres of water as well as the all the extras you need for a long day in the saddle. Different types of valve are favoured but essentially they all work in a similar way with a bite valve allowing you to drink freely but not to dribble when unused.
Bladders range from less than a litre up to three but not much more. The biggest variation is in the volume of available storage. When trying on a pack make sure that it sits comfortably when you are bent over in a riding position. Look for chest and hip belts that will help keep it still and padded shoulder straps for comfort. If you are riding in hot conditions check that there is a mesh layer or provision for air flow between the pack and your shoulders.