A ring-shaped metal rolling bearing cage, which has cage pockets for receiving rolling elements. The cage is formed by a first and a second cage segment. Adjoining ends of the cage segments are connected to one another by suitable connection assemblies. At least one of the assemblies permits a change of the cage diameter when the cage temperature changes. The suitable assembly, on one side, is configured as a joint mechanism and, on another side, as a locking mechanism, and at least one of the assemblies has a lash. A rolling bearing cage configured with the joint mechanism and the locking mechanism can be mounted with low time expenditure in a simple and reliable manner over a shaft, particularly in the case of an idler pinion mourning.