So - an entry of 22 inches really means a 22.5' frame size, 19 means 19.75', 25 means 25.5'. For some entries, only a two-digit number was given, the extra 1/2 or 3/4 inch was dropped.

Frame Sizes in the SN list below are as given on the paper copy.

Just disregard it when looking up the number in the tables below. This may be more prevalent on lower level models.

Some frames in this period have a leading 'A' before the 6 digit number.

The 58 or 60 refer to the angle between the seattube and the downtube. This designation is not part of the serial number but is a model number of the shell. The new bottom bracket shell is typically marked with 58TSI (or more rarely, 60TSI). Isaac designed new lugs and a new bottom bracket shell for Trek. Some early and mid 80s bottom brackets were marked with 58TSI or 60TSI.Some of these are presented in the 83, 84 link at the bottom of the table. Some of the Model 170 serial numbers are 6 digits but do not follow the numerical sequence.For example, a 1981 frame appearing on the list as a Model 610 could have been built into either a 613, 614, or 616 bike.

For some years, the model number given may be the lowest number (or an X00 number) for a series of models that have the same frame.

This may be a result of subcontracting some frame fabrication. The year designations in the table are approximate not all of the runs are sequential in time.

This journal information is summarized by year in Table I. At some time late in each year (generally September or October) frames were built for (then painted with colors for) the next model year.

Table I contains dates of frame serializing, and are not necessarily model year.

Trek tx900 serial number database