The Osprey Siskin 8 hydration backpack is great for your mountain biking adventures, when you need to pack a bit more than just water. The Siskin 8 is a high-performing mountain biking pack that provides stability and comfort on the gnarliest of trails; it allows you to bring just what you need (and nothing more) on your ride. The rolled, soft-edged harness contours to the upper shoulders to keep the pack close to your body and provide stability. The U-zip main compartment opens wide to stuff a spare tube, flat repair tools, enough space for change clothes and even a sandwich.