Bicycle with folding frame having a frame defining a lower longitudinal member which rotatably supports a rear wheel and a pedal crank shaft. A saddle upright and a handlebar upright are hinged to the lower longitudinal member, are substantially parallel to one another and are joined by an upper cross-member which is substantially parallel to the lower longitudinal member and is hinged to the uprights to provide an articulated-parallelogram coupling. A steering sleeve is articulated to the handlebar upright, supports a front wheel, and is associated with a handlebar. A locking bar for retaining the frame in operating position is furthermore provided and is arranged diagonally to the articulated parallelogram.