I've been using a Carradice Barley to carry commuting gear for the past 5 years. I also own a Pendle, which is their next largest bag, but the Barley will hold everything I need for commuting 99% of the time. I have also used rack-top bags and panniers, but prefer the Carradice bags for commuting. Due to their position right behind the saddle, they have little effect on bike handling and balance -- unlike other options. I did find that the Carradice Bagman rack is necessary, however, to keep the bag from swaying and hitting the backs of my legs when pedaling.