It's an L so that makes it circa 47, but whats the Goodyear Marathon badge mean? is that some sub division of Columbia?
there are some interesting features to this bike like the seat post looks like a 5/8ths post and the clamp is built into the frame
There is also a mud flap on the front fender. any one with more specific info about the Goodyear Marathon badge? I already read the Mr Columbia site looking for more specific information....
The attached may be an applicable explanation regarding a Goodyear badged bicycle sold through Goodyear Tire Stores. Regarding the Colson Goodyear, I've been told that they incorporate a "G" into their serial numbers for bikes that were specifically meant to go to Goodyear. I hope I'm not confusing the issue with an answer that's not directly related to your bike.