• If you're just taking tools and a tube, lunch, and a jacket, a Barley/Super C Audax is great, and would be ideal for a century ride. I use mine on a Carradice Classic Rack (needs a saddle with bag loops) but have found it's ok without a support, especially if you put some correx or similar inside the bag to stiffen it up. If you don't travel particularly light/want to take a picnic blanket/might want to use it to pick up shopping/want to use it for credit card touring, get a Nelson or Nelson Longflap; marginally heavier, but much more useable volume.

About