This is a decent explanation, Hostel Shoppe - Chainring Bolt Circle Diameter (BCD) MeasurementSo If I find a 53T sugino chain ring what do I measure to get BCD, or whatever the critical measurement is.
Fred at Raven can't help you? Very surprising. Also, have you tried Greatland Sports on College near that freeway? Last time I was there those two shops appeared to be the type that would try to find the part rather than sell you a new bike, but I don't really know.