Wheel for pedal-assisted bikes, comprising: - at least a fixed structure associable with the frame of a bike having a driving pedal crank; - at least a circle element (10, 11, 12) mounted on said fixed structure in a rotatable way around a main rotation axis; - at least a propulsion disc mounted on said fixed structure in a rotatable way and connectable to said driving pedal crank; - motion transmission means (14, 15, 16) for the transmission of the rotary motion from said propulsion disc to said circle element (10, 11, 12), comprising: - at least a speed gear device suitable for changing the motion transmission ratio from said propulsion disc to said circle element (10, 11, 12); and - at least a first detection device suitable for detecting the force transmitted to said circle element (10, 11, 12) from said propulsion disc; - at least an electric motor (54, 55) associated with said fixed structure and suitable for cooperating with said propulsion disc to motorize said circle element (10, 11, 12), said electric motor (54, 55) comprising a statoric element associated with said fixed structure and a rotoric element associated with said circle element (10, 11, 12); - at least a processing and control unit associated with said fixed structure, operatively connected to said first detection device and to said electric motor (54, 55) and suitable for controlling the activation of said electric motor (54, 55) according to the force detected by said first detection device; wherein said circle element (10, 11, 12) comprises at least a central boxed casing suitable for containing said motion transmission means (14, 15, 16), said electric motor (54, 55) and said processing and control unit; characterised in that: - said statoric element and said rotoric element are substantially ring-shaped and arranged substantially around said motion transmission means (14, 15, 16); - said wheel comprises at least a power supply unit associated with said fixed structure and suitable for electrically supplying said electric motor (54, 55), said power supply unit being contained in said central box casing. - at least a fixed structure associable with the frame of a bike having a driving pedal crank; - at least a circle element (10, 11, 12) mounted on said fixed structure in a rotatable way around a main rotation axis; - at least a propulsion disc mounted on said fixed structure in a rotatable way and connectable to said driving pedal crank; - motion transmission means (14, 15, 16) for the transmission of the rotary motion from said propulsion disc to said circle element (10, 11, 12), comprising: - at least a speed gear device suitable for changing the motion transmission ratio from said propulsion disc to said circle element (10, 11, 12); and - at least a first detection device suitable for detecting the force transmitted to said circle element (10, 11, 12) from said propulsion disc; - at least a speed gear device suitable for changing the motion transmission ratio from said propulsion disc to said circle element (10, 11, 12); and - at least a first detection device suitable for detecting the force transmitted to said circle element (10, 11, 12) from said propulsion disc; - at least an electric motor (54, 55) associated with said fixed structure and suitable for cooperating with said propulsion disc to motorize said circle element (10, 11, 12), said electric motor (54, 55) comprising a statoric element associated with said fixed structure and a rotoric element associated with said circle element (10, 11, 12); - at least a processing and control unit associated with said fixed structure, operatively connected to said first detection device and to said electric motor (54, 55) and suitable for controlling the activation of said electric motor (54, 55) according to the force detected by said first detection device; - said statoric element and said rotoric element are substantially ring-shaped and arranged substantially around said motion transmission means (14, 15, 16); - said wheel comprises at least a power supply unit associated with said fixed structure and suitable for electrically supplying said electric motor (54, 55), said power supply unit being contained in said central box casing.