Correct bearing size is 1/4 inch, 11 balls on each side. Getting the proper cups, spindle and cotter pins can be complicated. It would be best to get assistance at a local bike shop or co-op. If not the C & V forum will probably have the most people able to help you. I have the knowledge, but not the time right now to explain everything you need to consider. and it's quite a bit to write out and explain. Again, in-person help would be much preferable, and it may be useful to know where you are located.