Patent ID: 8490514

Claim:
A pedal-crank assembly for bicycles, comprising: a crank including an end with a threaded hole, and a bush having external threads engagable in said threaded hole, and an internal housing with an annular groove; and a pedal including a frame with a tubular housing, said frame having an upper side, a lower side and two opposite transverse walls comprising a first transverse wall and a second transverse wall, the first transverse wall being an internal transverse wall facing the crank when the pedal is mounted to the crank, and the second transverse wall being an external transverse wall facing away from the crank when the pedal is mounted to the crank; a pin inserted into said tubular housing of the frame, said frame being freely rotatable around said pin, the pin having an end section protruding out of the internal transverse wall of said frame, and said end section of the pin being housed in the housing of the bush of the crank when the pedal is mounted to the crank, said end section of the pin being in a male-female prismatic coupling with said housing of the bush of the crank, and said pin having a hollow tubular structure, the end section of the pin having at least one through hole; a rotary shaft having a first end section inserted inside the end section of the pin of the pedal and a second end section opposite to the first end section in an axial direction of the shaft, and the first end section of the shaft having at least one housing corresponding to said at least one through hole of the end section of the pin; a fast coupling-uncoupling member for locking the end section of the pin inside said internal housing of the bush, said fast coupling-uncoupling member including a spherical body partially housed inside said at least one housing of the first end section of the shaft and partially housed in said at least one through hole at the end section of the pin, wherein said annular groove of the bush is configured to surround the spherical body when the end section of the pin is inserted inside the housing of the bush; and a key lock inserted in said tubular housing of the pedal along the axial direction of the shaft, the key lock associated with a ring fixed to the second end section of the shaft and located inside said tubular housing of the pedal, said key lock being configured to be actuated to move said ring to rotate the shaft about the axial direction and to move said shaft in the axial direction toward the crank so that the spherical body is locked between the pin of the pedal and the bush of the crank so as to secure the pedal with the crank.