To ensure maximum comfort when biking, the shoulder strap shape and sternum strap placement accommodate your natural bike-riding position. 18L is perfect capacity for your daily commute, but the side panels can also be unzip to expand the backpack's carrying capacity to 50% if needed. The roll-top closure and water-resistant coating keeps items dry when you're biking in the rain. Thule Paramount commuter backpack is built for bike commuters and is the laptop backpack you can rely on for everyday life on two wheels.