I converted a cottered Raleigh 20 to a cotterless ST crankset by replacing the spindle with a mountain bike ST spindle. Following Sheldon Brown's site I was expecting to need smaller bearings, but it all went together with the same cups (including lockring) and 0.25" bearings. Mostly helpful to me to lower the weight and make changing the crankring easier now that it is 110 BCD. Good luck.

-Will