Suntour may have started producing bicycle components in 1912, but it wasn’t until 1972 that they decided to start using date codes to indicate the year in which they were manufactured. The codes consist of two letters stamped on each component – the first letter representing the year and the second denoting the month.
On the left side of this page is a chart which shows the codes with the corresponding year and month. Such information has become exceptionally important for those who are building period correct bikes.
For example, a Suntour Mountech rear derailleur with the code “AF” on the back plate manufactured in June 1984.
The same or similar date code systems were later adopted by Shimano, Nitto, Sugino, Sansin, Sunshine an more.