Many bikes in the Dahon line fold into slightly larger packages than the Mini, but much smaller than the DT (the website has the folded package size). My Dahon Mu SL is light and small when folded, but pricey. The best folders tuck the tire under the frame, though. So your best bet would be an 18" Birdy (but very expensive). There is nothing out there as competatively priced as a Downtube, so be prepared to fork out some $$.