Sorry for he weird question.
It's about Chainrings. Is there anyway to determine the overall, outside diameter of the ring if you know the tooth count and/or BCD?

I am having an issue fitting a single speed crank on a converted mountain frame because the ring (48t) is hitting the chainstay. I just want to know if buying a smaller ring will clear the stay. I already bought the crank from the internetz and can't return it so if possible am trying to wedge the thing in anyway I can.


My crank: Sram S300 1.1 courier [130 BCD, 48t (fixed spindle)]


If there is no way of calculating it, does anyone have a Sram 39t 130 BCD ring on their bike they can measure for me? I think that is the smallest that will fit on my spider. Thanks...

Thank You.