From what we can tell there were 3 welders all identified by a single letter - their first initial(there are also prefixes for special edition bikes but they are quite rare and can be dealt with on a case to case basis ie T for team rider bike). We think all bikes are manufactured in the eighties - you would not believe how hard it was to crack this code - the bikes made in the seventies have totally different serials - which still haven't been deciphered yet2. How many welders are there? Is the welder always identified by a single letter?1. Are all bikes manufactured in the eighties?2.