hi rex,it's not a bantam frame as its shape at the rear is different,also the shocks were not used by bsa, also thee serial no.52638 is not bsa.I bought the bike as a bsa,like you i thought it was a bantam d1?the shape of the frame is more like motobecane at the rear ,but its not ,what a puzzle ha ha,it has the DKW look with the different rear end.thanks for your reply peter.