Does anybody know of a third party bag or DIY bag that can be attached to the rear of the Brompton? I was riding to work with a small bag strapped in at the back rack (my Brompton bag upfront was full), but the clearance between my heal and the strapped bag was so tight, I could barely peddle.

So, I think I need a tall, skinny bag that can be anchored to the rear rack itself, and ideally, can be converted into a messenger style or at least shoulder type bag when not in use on the bike itself.

Any suggestions other than the rear rack bag that Brompton promotes? Thanks in advance...