When looking for a bag, see if you can find one with an option to also open the bag from the bottom and on that has a rain cover contained within the actual bag.
Look for external pouches where you can keep tools and spares for quick access.
If the bag has a little loop on the back to fix a red light to, then lekker.
Chest and waste straps are also good to have.
For a good many years I used to commute daily, come rain or shine, and always ended up using the K-Way bags. They are tough, reliable and Cape Union Mart respect and honour the warranty if something goes wrong with a zip.
