Chain force measuring device for mounting on a bicycle

A chain force measuring device adapted for mounting on a bicycle, the bicycle including a frame fork and a wheel axle on which a chain force is exerted when a cyclist is pedaling, and which is mounted relative to the frame fork so as to be shiftable forward by the chain force in a longitudinal direction, said chain force measuring device comprising:

• a dropout body unit having
• a frame connecting portion which is adapted to be connected to the frame fork,
• an axle connecting portion which is opposite to said frame connecting portion in an upright direction that is transverse to the longitudinal direction, and which is adapted to be connected to the wheel axle for being shifted therewith,
• an accommodation space which extends in the upright direction to terminate at an overhang surface that borders said frame connecting portion, and a shiftable surface that borders said axle connecting portion, and which further extends forward to terminate at a limiting wall surface, and
• a force transmitting member which is disposed on said shiftable surface, which extends toward said overhang surface, and which is spaced apart from said limiting wall surface by a sensor activating zone;
• and
• a hall sensing unit including
• a sensor which is disposed downwardly from said overhang surface to confront said sensor activating zone, and which is configured to extend in the longitudinal direction,
• a slidable carrier which is disposed in said sensor activating zone to be spaced apart from said sensor in the upright direction, and which has a pushed end configured to abut against and be shiftable by a pushing force of said force transmitting member toward said limiting wall surface when a chain force is exerted on the wheel axle, and a head disposed to confront said limiting wall surface,
• a biasing member disposed on said head and configured to abut against said limiting wall surface to provide a biasing force counteracting the pushing force, and
• a magnetic element disposed on said slidable carrier, and spaced apart from said sensor by a predetermined distance such that a magnetic field generated thereby is changed when said magnetic element is shifted with said slidable carrier relative to said sensor so as to give off a signal indicative of the magnitude of the chain force.