Many early Trek bottom bracket shells have a one or two letter code stamped separately from the serial number.

This was made by the individual framebuilder to mark his/her work.

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There's an easy way and a more time-consuming method to find out the year your Schwinn Stingray was made.

Modern Stingrays -- those made in the 21st century -- have a date code stamped into a specific area of the bike.

Date codes, if you know how to read them, will tell you what year Schwinn manufactured the bike. Instead, you will have to find and use their serial numbers to determine their manufacturing year. It will be on the head tube, the A-frame or the seat tube.

An example would be 'G0181' and equates to "Giant, January, 1981".

Everything on this web site is (c)2013 VVVintage Vintage Bicycles and may not be used in any way without written permission (CT = Cycletruck; WZ , S-10 = Whizzer; Tdm = Tandem.If you contact the Giant customer service they will be happy to decode the serial number for you and give you the date and any other information you are looking for. the global site so you can choose the appropriate country for you.Timothy Banas has a master's degree in biophysics and was a high school science teacher in Chicago for seven years.He has since been working as a trading systems analyst, standardized test item developer, and freelance writer.New numbering system: First letter is the month; first digit is the year.D836694 = April 1958 1959 - A900000 1960 - A000000 1961 - A100000 1962 - A200000 1963 - A300000 1964 - A400000 New numbering system: First letter = month; second letter = year.This tool searches a database of Schwinn serial numbers and if it finds a match to your serial number then it will display the information available for your bike.Notes: This tool works for Schwinn bikes from 1948 to 1982.Otherwise, you can find online databases that match Schwinn serial numbers to manufacturing dates.Can someone please explain what these three numbers mean on the pedal crank housing? Not much help but FWIW, the number on my early-1970's Schwinn Suburban is on the steering housing, two letters followed by six digits, in the range of HK549xxx.Trek frame serial numbers (SNs) are typically stamped into the bottom of the bottom bracket shell.In the case of some early 80s Treks, the number is under the plastic cable guide on the bottom of the shell.The dates coded in the serial numbers, or the dates inferred from the numbers, are dates on which the new frames were stamped with serial numbers (serialized).These dates are not necessarily the same as the model year of the frame. I have included a photo of the results from my bike.