Abstract: A bicycle with collapsible frame, which incorporates front and rear frame posts and at least one cross-beam interconnecting said frame posts. The bicycle, which with one of a few simple hand manipulations, in a few seconds, can be folded into a compact unit. The bicycle has an absolutely rigid frame when the bicycle is in its position of use, and in collapsed position it is only little bulky with a substantial extension in one direction only. The cross-beam of the frame is a two-part cross-beam. The two parts of the cross-beam are articulatedly connected to each other and to the frame posts. The two parts of the cross-beam at folding of the frame are pivotable towards the front and the rear frame posts respectively.