Spindles used in machine tools, especially machining centers, must operate at high speeds with high stiffness and low temperature rise in order to achieve improvements in productivity and accuracy of the machine. Usually, preloaded angular contact ball bearings are used to satisfy these requirements. However, during high-speed operation, bearing internal clearance is reduced due to thermal and centrifugal expansion of inner ring. Besides the expansion of the inner ring, the centrifugal force acting on the balls increases the preload on the bearings. As a result, these bearings can have problems of short life and seizure. Therefore, in high-speed operations, it is important to simulate the increase in ball contact load on races and determine the optimum internal clearance for the bearings. This paper introduces an analytical method to calculate ball loads considering the centrifugal effects on the inner ring and balls simultaneously.