When travelling in a curve, the tires provide the centripetal force needed for the acceleration towards the center of the curve. The capsizing moment provided by gravity acting on the motorcycle center of mass when leaning into a corner is balanced by a righting moment generated by centripetal forces in the contact patches when all is working correctly. If, having reached a given lean angle, the centripetal forces are reduced then the motorcycle increases its angle of lean until it touches the road surface, usually unseating the rider in the process.