I don't. I tried a few times but didn't like the effect on the bike's performance. I have about 6 backpacks lying around that I've collected over the years. I settled on a Burton snowboard backpack that is about 15 years old. I have a 20 mile R/T commute. It has thick padded straps and thick back panel and sinches down around my sternum and waist. I haven't weighed it but I do carry a full suit outfit plus small lunch.