Alternating drive, primarily for bicycles and similar driven vehicles, wherein the vehicle comprises a frame and a driven wheel rotatably connected to the frame, said drive comprising a pair of identically designed drive units with opposite driving directions mountable to respective sides of the frame, said drive units each comprise respective swinging arms (10, 10') pivoted around a common swinging shaft mountable in the frame to perform alternating swinging motion around the swinging shaft, each swinging arm (10, 10') has a respective driving arm (16, 16') with an edge defining a driving path (18, 18'), said units comprise a common driving shaft as a driving axis of rotation mountable and rotatable in said frame for circular motion around said driving axis, each of said driving units comprises a respective bolt (9, 9') with an axis substantially parallel to and radially offset from said driving axis and connected to and rotating with said common driving shaft along respective circular paths around said driving axis, and a driving wheel (15, 15') rotatably mounted on said bolt (9, 9'), said driving wheels (15, 15') are connected to the associated one of said driving paths (18, 18') so that the rotation of said driving wheels (15, 15') along the respective circular paths makes the driving wheels (15, 15') roll in a first and then in a returning second direction along said associated driving path (18, 18') causing said swinging arm (10, 10') to perform an alternating swinging motion, said driving wheels (15, 15') are mechanically connected to each other and in each position they are by 180° angularly offset with respect to each other around said driving shaft, respective flexible ropes (28, 28') are connected to an associated one of said swinging arms (10, 10'), and respective biased rope drums (61, 61') mountable around the shaft of said driven wheel and connectable to the driven wheel in a manner that allows transmission of torque to said wheel from said rope drum (61, 61') only when the respective rope drums (61, 61') are rotated in forward direction, wherein said ropes (28, 28') are connected to and wound with respective predetermined number of turns around the associated rope drum (61, 61') so that during the driving operation the number of said turns is changing in a mutually alternating manner, wherein each swinging arm (10, 10') further comprises: a head portion (14, 14') surrounding said swinging shaft and connected to inner end of said driving arm (16, 16'); a traction arm (17, 17') connected with inner end thereof to said head portion (14, 14') so that said driving arm (16, 16') defines an angle with said traction arm (17, 17'); and a connection arm (20, 20') interconnecting outer ends of said driving arm (16, 16') and of said traction arm (17, 17'), characterized in that said driving arm (16, 16'), traction arm (17, 17') and connection arm (20, 20') define together a substantially triangular opening, and said driving wheel (15, 15') and its shaft are both positioned in said opening, said traction arm (17, 17') defines a traction path (19, 19') at its edge facing towards said opening that determines substantially the momentary transmission ratio, and each drive unit comprises at least one rope wheel (26, 26') so that said rope (28, 28') is wound around said rope wheel (26, 26') that comprises a shaft (35, 35') guided along said traction path (19, 19').