Bags and backpacks
Cycle couriers use shoulder-bags or backpacks because they are convenient – there is no lost time detaching and remounting panniers, and they are more flexible than panniers in the loads they will take. They are more comfortable to wear when on a bike than walking and most will have a large main compartment and a variety of smaller pockets for keys, money etc.
Courier bags usually have a 15-20 litre capacity or more, but it’s a good idea to make sure you’re comfortable carrying amounts like this on your back before attempting any long distances, and always make sure you’ve adjusted the straps to keep the bag secure and prevent it from slipping around your body.
Many cycle bag manufacturers also make an ‘office’ style bag, which will have a padded compartment for a laptop as well as space for files, extra clothes and more.