I use a relatively large seat bag, a top tube bag and my jersey pockets to hold what I need. Usually, I plan my routes to pass by a convenience store or gas station for extra provisions. This past weekend, DH and I did a route that we weren't sure had a store along the way, so we brought our Cambelbaks. Ouch. While I find it to be relatively comfortable on my mountain bike (and it's more upright position), I found it hard to wear by the end of our 45-mile ride. My low back was killing me. My guess is that I could get used to it, but I don't think I really want to use it for most rides.