The cranks on my old Takara that I am fixin to make into a fixie are old cottered Suginos but seem to be in decent shape. The problem is if I want to have just the 40 tooth chain ring I have to get new cranks because only the 52 chain ring is attached to the cranks and the 40 tooth is bolted to the 52. The question: can I just leave both chain rings on and use only the 40 tooth one? It won't look terribly cool, but it should not be a problem.

Has anyone else do this?