I really like my Jandd Handlebar Pack II. I was a little skeptical when I bought it but it is completely solid and easy to remove and transfer to another bike. However, it probably won't work with a 31.8 stem. The bag collapses flat for travel and has plenty of useable pockets. The rain cover also has a clear window so you can still see your map. I really didn't care for my Ortlieb bag at all and like this much better.