My pre war Schwinn New World has a balloon type one piece BB shell. It has an adapter to use cottered crank arms in it but they are some odd size and use the one piece crank chainring. I am looking for an adapter that lets me use standard cottered crank arms. Does anyone our there have one? They still make these for BMX bikes and such but they are for tapered spindles and won't do what I want them to do. Thanks Sam D.