Abstract: There are provided a torque detection shaft loaded with a torque from outside, and a pair of magnetic field sensors and provided in the vicinity of a surface of the torque detection shaft. The torque detection shaft has magnetostrictive characteristics and also has six magnetization bands to magnetized in the circumferential direction of the torque detection shaft and polarized so that magnetization directions of the adjacent magnetization bands are opposite to each other.

Abstract: This invention is a bicycle torque detection apparatus for a bicycle having a pair of cranks each having a pedal, and a rotating shaft supporting the cranks to allow a user to step on the pedal to turn the cranks and drive a gear engaged with a chain. It comprises a detection section or rotating shaft consisting of magnetic alloy having magnetic anisotropy, the permeability of said detection section or rotating shaft being changed by torsional stress caused by the rotation of the cranks, and a coil unit disposed on the outer circumference of the detection section or rotating shaft to detect a change in the permeability of the detection section or rotating shaft.