I recently picked up an old CCM Imperial 3-speed women's bike. When I first looked for a serial number, I couldn't find one. A piece of advice I've heard several times is to look for a date on the rear hub to help date the bike. The number 61 is stamped on it, so the bike was made about 1961? Wrong! I later found a serial number near the base of the seat tube - the letter C followed by 5 digits. This letter was used in 1970. So it seems that some hubs could have sat on the shelf for quite a while before being installed on a bike. Any comments?