Or even better yet, you can simply adapt an already sewn bag (very easy & quick with minimal sewing) or make & sew one up yourself entirely (a bit more advanced sewing knowledge required) for the Brompton block's unique metal frame-or simply attached directly to the handlbars. I have done both with extremely good results as you can see for yourself. Below are some samples-from left; the Beaded Bike sewn and heat-set beaded entirely by myself for the Brompton, Giraffe print for use on all of them, Blue Rear Panniers bags custom sewn by me for my Jetstar bike, and Cat-In-The-Bag to get a feel how big the rear bags are-that I have done for my own Brompton and my other 2 folding type bikes: