TWI769802B

This invention provides a pedaling force detection mechanism for an electric assisted bicycle, including a unidirectional ratchet sleeve sleeved on a crank shaft, an active end cam sleeved on the unidirectional ratchet sleeve, a passive end cam combined to the active end cam, a coupling shaft sleeve connected to the passive end cam and to a main gear, and a strain gauge assembly. The strain gauge assembly is arranged between the passive face cam and the coupling shaft sleeve and includes an elastic ring-shaped seat body and a strain gauge arranged on the elastic ring-shaped seat body. The main gear is adapted to restrain the passive end cam through the coupling shaft sleeve, such that the active end cam pushes the passive end cam away in an axial direction of a crank shaft, causing the passive end cam to exert pressure on the elastic ring-shaped seat body of the strain gauge assembly to deform the elastic ring-shaped seat body. The strain gauge is adapted to transmit a start signal to an auxiliary power assem