A ball bearing is provided which includes inner and outer races each having a raceway groove; balls; and a retainer made of a synthetic resin, and in which abnormal noise is reduced. Either the raceway groove of the inner race, or each of the raceway grooves of the inner race and the outer race has a radius of curvature which is 104% or more and 109% or less of the radius of each of the balls.

A hub for a bicycle includes a hub shell and an axle device. The hub shell is supported rotatably relative to the axle device by way of bearing devices. A bearing device is configured as a roller bearing, and includes two bearing rings with rolling members disposed between, and is sealed axially outwardly. Between the bearing rings, the roller bearing includes a modular unit, at which a sealing unit is configured for laterally sealing the roller bearing, and including guide units protruding laterally inwardly from the modular unit for guiding the rolling members.

First and second bearing cage halves each having an annular base body and a plurality of pins extending from the base body and a plurality of pin receptacles, the first and second cage haves forming a bearing cage when the pins are received into the pin receptacles. A body of sacrificial material is located on the pins and/or in the pin receptacles which body is configured to be melted ultrasonically to join the first cage half to the second cage half and form the bearing cage.

A deep groove ball bearing includes an outer ring, an inner ring, a cage, and steel balls. The cage is provided between the outer ring and the inner ring. Pockets are formed in the cage, and the steel balls are placed in the pockets. The cage is split into an upper cage body and a lower cage body. Pocket grooves are formed alternately in each of the upper cage body and the lower cage body. A connecting portion is provided between adjacent pocket grooves in the upper cage body. A positioning portion is provided between adjacent pocket grooves in the lower cage body. An insertion piece and an insertion groove are provided between the connecting portion and the positioning portion. The insertion piece and the insertion groove are configured to be fixed with each other to form a fixed connection between the upper cage body and the lower cage body.

A ball bearing is provided which includes inner and outer races each having a raceway groove; balls; and a retainer made of a synthetic resin, and in which abnormal noise is reduced. Either the raceway groove of the inner race, or each of the raceway grooves of the inner race and the outer race has a radius of curvature which is 104% or more and 109% or less of the radius of each of the balls.

A bearing unit includes a radially outer ring, a radially inner ring, a row of rolling bodies interposed between the radially outer ring and the radially inner ring and a cage for retaining the rolling bodies, where the cage includes a rib with a circular base and a plurality of circumferentially spaced fingers defining a plurality of pockets for holding the respective rolling bodies of the row of rolling bodies. Also, a plurality of inserts formed separately from the cage, each of the plurality of inserts being inserted inside seats of corresponding adjacent pairs of fingers of the plurality of fingers to limit circumferential deformation of the fingers.

A cage includes a first sub-part having a plurality of first partitions integrated as a whole and a plurality of first pocket portions formed by adjacent first partitions. A first engaging portion is formed on at least one of the first partitions. A second sub-part includes a plurality of second partitions integrated as a whole and a plurality of second pocket portions formed by adjacent second partitions. A second engaging portion is formed on at least one of the second partitions. A pocket is formed by the first pocket portion and its corresponding second pocket portion. Each first engaging portion snaps with its corresponding second engaging portion. The cage overcomes the harmful umbrella effect found in a one-piece polymer prong-type cage, so that the bearing equipped with this cage can operate under very high speeds. The cage can be part of a ball bearing.

A bearing unit may be provided with at least one row of rolling bodies and at least one cage for retaining the rolling bodies. The at least one rolling cage may include a base rib; a plurality of fingers spaced circumferentially and extending at least from one side of the base rib; and a plurality of partially spherical cavities for holding the rolling bodies, each cavity being defined by the partially spherical concave surfaces of a pair of fingers of the plurality of fingers and of the base rib. The rolling bodies and the cages are in contact with each other via a plurality of protrusions formed on the partially spherical concave surfaces of the fingers and of the base rib. At least one lateral protrusion may be formed along the surface of each finger of the plurality of fingers of the retaining cage.

A two-part bearing cage for a rolling bearing includes a first cage part and a second cage part. Each cage part includes an annular base body with a plurality of bars extending axially from the annular base body and/or a plurality of complementarily designed bar receptacles. The bars of one cage part engage in the bar receptacles of the other cage part to form cage bars for defining cage pockets configured to receive the rolling elements of the rolling bearing. Each bar includes a claw and each bar receptacle includes a connection portion such that each connection portion and its corresponding claw form a snap joint.

A rolling bearing includes a cage constructed by coupling a pair of split members that are split into halves in an axial direction of the rolling bearing. At least one of the split members has an engagement portion that protrudes in the axial direction toward the other one of the split members. The other one of the split members has an engagement groove that extends along the axial direction and houses the engagement portion. The engagement groove has an insertion port through which the engagement portion is inserted in the axial direction. The insertion port is formed at an end of the engagement groove that is closer to the one of the split members. At least one circumferential face of the engagement groove includes a first inclined surface that increases a circumferential width of the insertion port toward the one of the split members.