Quote Originally Posted by Robert Steinwandel View Post
I had thought that angular contact bearings could be used without preload,
They are always preloaded in this type of application. If you buy top quality then they will come as matched pairs with the preload built in. Being practical, good results can be obtained with lower quality bearings which are more affordable. Preload can be done with shims between inner or outer races, depending on which way round you mount them.