does anyone know how to remove a chain ring from a one piece crankset? i cant for the life of me get the chain ring off. its an early 1960's schwinn crankset with the standard factory chain ring on it (4 circles). Is there a special way or tool that i need to pry this thing off or is it an actual part of the crankset? I want to put on a new ring if i can get the old one off. Secondly, what will i need in order to put the new one on? is it a cotter pin that they used? any help on this would be much appreciated thanks!