Before choosing your backpack, ask yourself the following questions: "Exactly how long do I want to hike for?", "What type of terrain am I going to encounter? Will there be lots of up and downhill sections?", "Will I have to carry equipment for other hikers (for example children)?", "Will it be a self-sufficient expedition or am I going to stop over in gîtes?
Once you've answered these questions, you'll be in a position to match your needs to the type of hiking and the different types of bags available.
Whichever model you choose, ensure that your backpack has sufficient storage for your organizational requirements. Some people like to use pockets on the hip belt while others don't. Check that the bag has all the necessary adjustment features to ensure maximum comfort. For long walks, choose a bag with a reinforced back, a hip belt, chest belt and load-lifter straps on the shoulders as well as an adjustable torso length so that it will really fit you properly. Finally, to protect your back as much as possible, opt for a lightweight (empty) bag.
Important: Take time to try out your bag in store, packing it with equipment to assess how comfortable it is to carry. You can also borrow different bags from your friends and try them out, packed with gear, in the field. You can adjust the capacity depending on your size and preferences. An adult can carry roughly 25% of his body weight on his back. Make sure you don't exceed this limit or you could damage your back.