Patent ID: 8253412

Claim:
A rotation detector comprising at least: a housing through which an axle is inserted, said housing arranged between a hub of a wheel and a front fork of a two-wheel vehicle; a magnet provided on the inside of the housing for generating a magnetic field; and a magnetic detection device provided in the housing in a state capable of detecting a change of the magnetic field, the change being in accordance with a rotation of an object to be detected, the rotation detector characterized in that the object to be detected is formed from a magnetic material, wherein said magnetic material is different from a material of the hub and arranged to have at least a part to be detected, the part being rotated synchronously to the hub, wherein: the object to be detected comprises a support part comprising a concave part, the hub is provided with a projecting part, and the concave part is provided with a pair of inwardly facing protrusion parts protruded towards each other, and the pair of inwardly facing protrusion parts protruded towards each other hold and fix the projecting part.