The question often arises; "When was my bike made?"
I'd like to tell you, but I can't. I can guess, but I don't know for sure. The only way to really know is to check the serial number (found stamped on the underside of the bottom bracket); and then you have to know the code.
I heard a guy on bikeforums.net had set up a database of numbers to decode the system. It's simple: by gathering a large sample of serial numbers (and other information) you can pick enough clues out of the pile to crack the code. But I wasn't able to contact him, so I had to start my own database.
So far I have over 60 serial numbers. Most people I meet on the street are actually very forthcoming when they find out what I'm doing. I've also gathered any numbers I can find online. My little database, though patchy, is growing and starting to reveal patterns. When I have a good guess, I'll post up the code so anyone can find when their bike was made.
If you have a Sekine, I ask that you kindly email me ( rodoftheflies ) no spam, please ( @yahoo.ca ) the serial number and as many details about the bike as you have (every owner should know the serial number of their bicycle, anyway). I won't post this information online (but you can, if you want- comments below!). A clear photograph is best for reference (and your own insurance). Good additional information to include: type of headbadge, any frame decals, type of frame, style of dropouts, paint and chrome, components and their date codes, the more details the better.
And T-Mar, if you're out there, I'd love to compare numbers.