(I had this posted in another spot, but rather than continue with the old, I began a new one. I attempted to change the title on the other post in light of my recent findings, but I was unsuccessful. I began a new post in hopes of finding the right help. Thanks.)
I recently purchased a vintage bicycle and need help determining its identity. The bike has no markings or badge other than a serial number (M4J00615). I believe that the bike is a Fuji. Using a dating system I found on BikeForums.net (the formula that I used can be found below), I have arrived on a date of 1969. According to bikeforums.net, the bike was manufactured at plant M, in the year 1969 (4 = Showa 44 = 1969), in the month of October, and being the 00615 model made that year.
Using this serial number formula creates problems. The author knows of no bikes outside of 1971-1974 that use this formula. However, he does allow for the possibility of an earlier or later date than mentioned (please see section in red letters below). The bike is clearly Japanese and other dating systems for other bikes don't make sense (I've explored Miyata, Nishiski, Centurion, etc.).
The bike has some interesting features. The brakes and derailleurs are Shimano 600. The cranks are Sugino Pro Dynamic s. The Chain rings are made in France. The seat is Italian. The headset is Falcon. The shift levers are Campy. Under the paint near the dropouts, the frame is layered in chrome. Also, the fork appears to be layered in chrome under the paint. The bike may have been repainted and the components upgraded.
I have made contact with br. from classicfuji.com and he has been helpful. But given the components, he is uncertain that it is a Fuji. Fuji did not enter the US market until 1971. If my findings are right, the bike was likely brought over by a serviceman or businessman.
If you have any insight into bike, I would appreciate your input. Help me confirm my findings or show me my errors. I work as a bicycle mechanic, but I'm new to vintage bikes. I have found this process enjoyable.
Also, please give me some feedback on the cranks (Sugino Pro Dynamic s). I only found limited information on them. There appears to be unusual amount of interest in them.
Thanks for taking the time to read this post! Also, I have photos of the bike below.
Serial number format WXYZZZZZ where;
W = a letter, all cases to date being F, K or M, with F presumibly indicating Fuji.
X = a number, indicating the last digit of the Japanese Imperial calendar year, Showa reign (6 = Showa 46 = 1971, 7 = Showa 47 = 1972, etc.)
Y = a letter, indicating the calendar month of manufacturer (A = January, B = February, C = March, etc.)
ZZZZZ = four or five digit number sequence, probably indicating frame number during month
Example: F7C10256 indicates the 10,256th frame manufactured during March 1972.
* The serial number format may extend beyond 1971-1974, in either direction, but to date, data samples lie within this range.