A bicycle pedaling force detector is basically provided with that basically includes a first sensor circuit, a wireless communicator and a first electrical connection member. The first sensor circuit is coupled to a first housing that is configured to be mounted to a crank assembly. The wireless communicator is coupled to a second housing that is configured to be detachably mounted to a crank assembly. The second housing is a separate member from the first housing. The first electrical connection member is configured to electrically connect the wireless communicator and the first sensor circuit.