The Osprey Raptor 10 is a feature-rich mountain biking hydration backpack. The pack’s capacity is 600 cubic inches. With an empty hydration bladder the pack weights 2 lbs. 4 ounces or just over a kilogram. There are two sizes depending on torso length. I tested the Osprey Raptor 10 while mountain biking on trails along the Wasatch Foothills. I also took it for a few day hikes and cross country skiing.