A roller of a roller bearing providing a hollow bore in which a load cell is arranged, for measuring a radial load acting on the roller. The load cell is mounted to the roller bore in a non-fixed manner and includes one or more cantilever beams that extend in an axial direction of the roller. A contact element is provided on each cantilever beam. Each element further bears against a surface of the roller bore. At least one sensor is provided on each cantilever beam for measuring bending thereof, due to deflection of the beam in a radial direction perpendicular to the axial direction.