Note: This scheme is for all Chicago built non-Paramount models excluding 1962-1963 Superiors, 1964-1969 Super Sports and 1968 S/S Tourers (whose Serial Numbers are located on the left rear axle hanger and consist of a single letter code for the month [again, skip "I" and "O"], the last digit of the year and a 3-digit sequential build number -- e.g.'K6018' is the 18th frame built in October of 1966).If there is only one letter in the first twopositions, the first number or two numbers refer to productionyear.Date Codes occupy the first two, three or four positionsin a serial number.The 1970 Super Sports with Huret dropouts seem to have used a two digit year ('C70204' -- March, 1970, 204th frame).The 1979 Chicago built Le Tour and Super Le Tour models had their Serial Numbers on the left rear axle hanger and began with an 'S', followed by the standard letter/number scheme.Those Schwinn bikes produced before 1959 have no real system to numbering but the serials typically contain six or seven numbers or letters.
Schwinn began producing modern versions of the Stingray in 2004.
Schwinn used an alpha-numeric code during this time, with an example being D136694.
The first letter corresponds to the month made; in this instance D is the fourth letter of the alphabet, and April is the fourth month of the year, so the Sting-Ray was made in April.
If thefirst letter is a "A" through "M" it refers to production month("A" = January, "B" = February, etc.).
The letters "I" and "O" are not used, to avoid mistakingthem for numbers.