Wheel for pedal-assisted bikes, comprising: - at least a fixed structure having attachment means for the attachment to the frame of a bike with a driving pedal crank; - at least a circle element (10, 11, 12) mounted on said fixed structure in a revolving way around a main rotation axis; - at least a propulsion disk mounted on said fixed structure in a revolving way and drivable in rotation by said driving pedal crank; - motion transmission means (15, 16) for the transmission of the rotational motion from said propulsion disk to said circle element (10, 11, 12), which comprise at least a first detection device suitable for detecting the driving torque transmitted to said circle element (10, 11, 12) from said propulsion disk; - at least an electric motor (54, 55) associated with said fixed structure and suitable for cooperating with said propulsion disk to motorize said circle element (10, 11, 12); and - at least a processing and control unit (57, 58) 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 driving torque detected by said first detection device; wherein said first detection device comprises: - at least a measuring element (61, 62) which is subject to a stress condition due to the effect of the driving torque transmitted to said circle element (10, 11, 12) by said propulsion disk; - at least a measuring sensor which is arranged in correspondence to said measuring element (61, 62) and which is suitable for detecting said stress condition of the measuring element (61, 62) and for producing a corresponding electronic signal which can be processed by said processing and control unit (57, 58); - at least a first body revolving around said main rotation axis and operated in rotation by the motion of said propulsion disk; - at least a second body revolving around said main rotation axis and suitable for driving in rotation said circle element (10, 11, 12); and - characterised in that ramp means (74, 75, 76) placed between said first body and said second body and suitable for transmitting said driving torque from said first body to said second body and for producing an axial thrust on said first body and said second body along a thrust direction substantially parallel to said main rotation axis, said stress condition of said measuring element (61, 62) being produced by said axial thrust; and wherein said ramp means (74, 75, 76) comprise at least a substantially spherical motion transmission element which is housed in a first housing seat obtained on said first body and in a second housing seat obtained on said second body, at least one of said housing seats (75, 76) comprising at least a surface section which is inclined with respect to said main rotation axis. - at least a fixed structure having attachment means for the attachment to the frame of a bike with a driving pedal crank; - at least a circle element (10, 11, 12) mounted on said fixed structure in a revolving way around a main rotation axis; - at least a propulsion disk mounted on said fixed structure in a revolving way and drivable in rotation by said driving pedal crank; - motion transmission means (15, 16) for the transmission of the rotational motion from said propulsion disk to said circle element (10, 11, 12), which comprise at least a first detection device suitable for detecting the driving torque transmitted to said circle element (10, 11, 12) from said propulsion disk; - at least an electric motor (54, 55) associated with said fixed structure and suitable for cooperating with said propulsion disk to motorize said circle element (10, 11, 12); and - at least a processing and control unit (57, 58) 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 driving torque detected by said first detection device; - at least a measuring element (61, 62) which is subject to a stress condition due to the effect of the driving torque transmitted to said circle element (10, 11, 12) by said propulsion disk; - at least a measuring sensor which is arranged in correspondence to said measuring element (61, 62) and which is suitable for detecting said stress condition of the measuring element (61, 62) and for producing a corresponding electronic signal which can be processed by said processing and control unit (57, 58); - at least a first body revolving around said main rotation axis and operated in rotation by the motion of said propulsion disk; - at least a second body revolving around said main rotation axis and suitable for driving in rotation said circle element (10, 11, 12); and - characterised in that ramp means (74, 75, 76) placed between said first body and said second body and suitable for transmitting said driving torque from said first body to said second body and for producing an axial thrust on said first body and said second body along a thrust direction substantially parallel to said main rotation axis, said stress condition of said measuring element (61, 62) being produced by said axial thrust; and wherein said ramp means (74, 75, 76) comprise at least a substantially spherical motion transmission element which is housed in a first housing seat obtained on said first body and in a second housing seat obtained on said second body, at least one of said housing seats (75, 76) comprising at least a surface section which is inclined with respect to said main rotation axis.