Roller bearings

A roller bearing comprising:

• an inner ring defining a toroidal inner raceway rotatable about a bearing axis;
• an outer ring defining a toroidal outer raceway rotatable about the bearing axis;
• and
• a plurality of concave rolling elements arranged in a single row between the outer and inner rings;
• wherein each of the plurality of concave rolling elements is a symmetrical cylindrical roller having circular ends, a roller axis passing through the centre of the circular ends, and a concave side profile that extends continuously between the circular ends, the roller axis being aligned with the bearing axis;
• and
• wherein the toroidal inner and outer raceways each have a convex race surface that continuously engages the concave side profile between the circular ends of each concave rolling element with a first radius and extends axially beyond the circular ends of each concave rolling element with a second radius that is less than the first radius.