I actually use a Doubleplay bag sized for the 20 inch models for my Brompton. It is obviously loose-like a pair of relaxed fit jeans-but I never had any problems using with both my bikes. The Dahon fits very snug and can be a major hassle to fit it in. Another bag I have used for both bikes is a large black duffel bag for travel in trains. It looks far more neater and seems to blend in more with each bike's shape than the Doubleplay. I bought that for about $10.00 at the local 99 cents store nearby. Good bags are to be had if you know where to look and what bag to adapt to bike toting duties.