I have owned folding bicycles for over 7 years now. My bikes run the full gamut from Dahon 's 20 inch wheels to a more compact Dahon & Brompton 16 inch. For serious transport on crowded situations such as yours, think and go small (A.K.A the 16 inch range). My Brompton and former Piccolo both worked well in the commuting side of things (although the Brompton is a more compact fold & in that way might be a better choice). Size is supposed not to be an issue on crowded buses, but when a bus driver has to make a choice between your bike taking up precious space or cram more bodies, you might find yourself outside waiting for the next bus.

That is the one of the basic reasons why I kept the Brompton over the Dahon Piccolo. Size does matter! Always remember to factor in that variable when you take any bike along for a bus ride, even if you choose to use the front-of-the-bus bike racks to place your bike on. I choose not to exercise that particular option as I know of cases where the bus drives away before you have a chance to get your bike off it.