1.   Any person operating a bicycle shall obey the instructions of official traffic-control signals, signs and other control devices applicable to vehicles, unless otherwise directed by a police officer.
   2.   Whenever authorized signs are erected indicating that no right, left or U-turn is permitted, no person operating a bicycle shall disobey the direction of any such sign, except where such person dismounts from the bicycle to make any such turn, in which event, such person shall then obey the regulations applicable to pedestrians.