There are a number of ways to determine approx. age of a frame. Does it still have the original finish and decals intact? Various finishes and graphics can help determine age.
What type of lugs, dropouts, other fittings does it have? What tubing is it made out of? Any small details that are unique. All if these things may give as clue. We need to know more.
I have a neat Ron Cooper from the early 70's. Tell me about yours and I'll compare it to mine and others I've seen or owned. I had another one from about this ame period also. I FOOLISHLY sold it. I LUCKILY found another one. BOTH of them are fantastic bikes. I may gush more about them when I hear about yours. I'll save it for now. It's late.
Brian Baylis La Mesa, CA You aren't going to believe what a SHUMCK I've been. Just wait.
Apologies to all who wish only to debate fixed gear/wheel nomenclature,
but I just now acquired a Ron Cooper bike, and wonder how one goes about
figuring its date of birth.