When you're on your bike you don’t just have to rely on a backpack to take your gear with you, you can share the load on your shoulders with your bike frame.
A bike hydration pack it primarily a source of water for long rides whethe capacity of your water bottle just won't cut it. Whilst most bike backpacks will carry upwards of 2 litres of water, some will also have volume for extra gear such as tools, pumps, spares and food.
By adding a bag to your bike frame, you can move all the small things from your back and onto the frame, making the pack on your back lighter and more streamlined.
Browse both styles of bags here and you can work out what the best combination for your riding style will be.