CehowardGS or anyone that knows these bikes, do you happen to know the diameter of the seatpost on the Gran Prix "Racing USA"? I recently re-aquired the Grand Prix I bought new in 1985 (when I was a kid!). The OEM seat post has seen better days and I'd like to replace. I have a few 27.2 sizes laying around, but it's just a bit too big. Thanks for the feedback.