You have to go to a few shops and look. I didn't like any of the options when I wanted them for commuting in NYC. My requirement was that it didn't look dorky off the bike, and let's just say they go from mildly geek to all out dork. I ended up with a Knog messenger bag that had an attachment that would hang from the rack. It had its own issues but I even got some comments about my nice messenger bag from non-riders that didn't know it was also a bike bag. You may be able to find them on eBay but they stopped making them years ago.