To miniaturize a motor-assisted bicycle and reduce its cost by detecting rotation speed of a part to be detected which is provided in a rotary member constituting a part of a second transmission system between an electric assist motor and a second one-way clutch.
A rotation speed detecting means is constituted of a reluctor 87 and an electromagnetic pickup coil type sensor 88. The relcutor 87 having a projection 87a on its outer circumference is fixed to a rotary shaft 73 of an electric assist motor which constitutes a part of a second transmission system between the electric assist motor and a second one-way clutch 80. The sensor 88 is fixed to a left casing 46 of a casing. This rotation speed detecting means outputs pulses at every time when the projection 87a detects a detection part 88a. The obtained rotation speed is used for the operation control of the electric assist motor. The rotation speed of a rotary member having relatively high rotation speed is thus set to the bicycle speed so that the diameter of the part to be detected can be relatively miniaturized.
YAHAGI KUNIO
HONDA SATOSHI
TORIYAMA MASAYUKI
