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); and - 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); wherein said motion transmission means comprise at least a first detection device suitable for detecting the force transmitted to said circle element (10, 11, 12) from said propulsion disc, said first detection device in turn comprising: - at least a first plate rotatable around said main rotation axis and associated with said propulsion disc so as to be operated in rotation by the motion of said propulsion disc; and - at least a second plate rotatable around said main rotation axis and suitable to receive the rotation motion from the first plate, said second plate being associated with said circle element (10, 11, 12) through a prismatic coupling suitable for making the second plate rotatable around said main rotation axis together with the circle element (10, 11, 12) and at the same time for sliding the second plate along a sliding direction substantially parallel to said main rotation axis; the wheel for pedal-assisted bikes being characterised in that said first detection device further comprises: - at least a motion transmission part, for transmitting the rotation motion from said first plate to said second plate, which is associated with at least one of said first plate and said second plate and is suitable for engaging a grip ramp which is associated with the other of said first plate and said second plate and is inclined with respect to a plane transversal to said main rotation axis, the engagement of said grip ramp by said motion transmission part determining the sliding of said second plate along said sliding direction until it is arranged in a position corresponding to the force transmitted; and - at least a detection sensor for detecting the position of said second plate along said sliding direction, wherein said motion transmission part is composed of at least one bearing rotatable around a respective axis at right-angle to the main rotation axis. - 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); and - 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); wherein said motion transmission means comprise at least a first detection device suitable for detecting the force transmitted to said circle element (10, 11, 12) from said propulsion disc, said first detection device in turn comprising: - at least a first plate rotatable around said main rotation axis and associated with said propulsion disc so as to be operated in rotation by the motion of said propulsion disc; and - at least a second plate rotatable around said main rotation axis and suitable to receive the rotation motion from the first plate, said second plate being associated with said circle element (10, 11, 12) through a prismatic coupling suitable for making the second plate rotatable around said main rotation axis together with the circle element (10, 11, 12) and at the same time for sliding the second plate along a sliding direction substantially parallel to said main rotation axis; the wheel for pedal-assisted bikes being characterised in that said first detection device further comprises: - at least a motion transmission part, for transmitting the rotation motion from said first plate to said second plate, which is associated with at least one of said first plate and said second plate and is suitable for engaging a grip ramp which is associated with the other of said first plate and said second plate and is inclined with respect to a plane transversal to said main rotation axis, the engagement of said grip ramp by said motion transmission part determining the sliding of said second plate along said sliding direction until it is arranged in a position corresponding to the force transmitted; and - at least a detection sensor for detecting the position of said second plate along said sliding direction,