Suppose that a wheel is rotating around its axis in free space with no friction, with no external forces acting on it. In theory, the wheel will rotate forever with constant angular velocity. This velocity is assumed to be small (essentially non-relativistic). Now, consider an observer O moving with constant (high, relativistic) linear velocity relative to the center of the wheel, in a direction perpendicular to the axis of the wheel. O will perceive (although not strictly see) the wheel as contracted in the direction of the relative motion, but not contracted in the direction perpendicular to the motion. So O will perceive the wheel as an ellipse instead of a circle. So accoording to O, a point P at the perimeter of the wheel will move in an elliptic orbit around the moving center, changing its distance to the center of the wheel all the time. How can then O explain the physics of this motion of the wheel, w.r.t O's own frame of reference? Which forces act on the point P to give it such a strange motion?