I'll trust Waterford's references for PARAMOUNT serial numbers, which is what is being discussed ... not Schwinn serial numbers in general.
From: http://www.waterfordbikes.com/
----------- begin quote --------------
Capacity Added for the Boom Years
This system was used from January 1970 to the mid-1980's. It consisted of three components -
Month Code: This one letter code corresponds to the month with A=January, B=Febuary and so on. Because I is not used, September=J and December=M.
Year Code: This two digit code is the last two digits of the year - 86 is 1986.
Sequence Number: This two digit number represents the nth frame and/or fork scheduled during the month.
For example, H7634 is the thirty-fourth frame or fork scheduled during August of 1976.
-------------- end quote -------------
So, as previously stated, C7021 would be the 21st frame done in March 1970.
Steven L. Sheffield
stevens at veloworks dot com
veloworks at worldnet dot att dot net
veloworks at mac dot com
> Here's the page for Schwinn serial numbers:
>
> http://www.angelfire.com/
>
> C7021 doesn't correspond to any of the modern numbers.
>
> Calvert Guthrie
> Kansas City
>
> In a message dated 1/4/2002 9:39:44 PM Central Standard Time,
> stevens@veloworks.com writes:
>
>
> > C7021 would make it the 21st frame built in March of 1970.
> >
> > Steven L. Sheffield