A wheel bearing apparatus that supports a wheel of a vehicle relative to a suspension apparatus and incorporates a wheel speed detecting apparatus to detect a rotational speed of a wheel of a vehicle to control the anti-lock braking system (ABS) is known. Such a bearing apparatus generally includes a sealing apparatus between an inner member and an outer member. The inner and outer members are rotatable relative to each other via rolling elements (balls). A magnetic encoder with magnetic poles alternately arranged along its circumference is integrated into the sealing apparatus. A wheel speed detecting sensor is provided to detect the variation in magnetic poles of the magnetic encoder according to the rotation of the wheel.
The wheel speed sensor is usually mounted on a knuckle after therow outer raceway surfaces 51a, 51a. A cylindrical portion 55b extends from the inner raceway surface 55a. The cylindrical portion 55b inner circumference includes a serration 55c for torque transmission.
The inner ring 56 is formed on its outer circumference with the other inner raceway surface 56a opposite to the other of the double row outer raceway surfaces 51a, 51a. The inner ring 56 is press-fit onto the cylindrical portion 55b of the wheel hub 55, via a predetermined interface. The inner ring 56 is axially secured on the cylindrical portion 55b by a caulked portion 57. The caulked portion 57 is formed by radially outwardly plastically deforming the end of the cylindrical portion 55b. 
Double row balls 53, 53 are contained between the double row outer raceway surfaces