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. Just remove the plastic cable guide to see the number. The other place Trek (or their subcontractors) stamped the SN is at the lower end of the seat tube.
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. On some bottom brackets there are two codes: one indicating the maker of the main triangle and the other for the maker of the rear triangle or perhaps the person who cut and shaped the tubing, if not done by the framebuilder. If you know which mark was used by a particular craftsman, please let me know.
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. At some time late in each year (beginning generally September or October) the frames produced were created from designs, and painted with colors, for the next year.
"Rub the area with candle wax of a color that contrasts with your paint. Lightly wipe it off with a rag. The wax stays in the indented area of the S/N. Now you can easily read the number. I have included a photo of the results from my bike. In this case I used a red candle to make the serial number stand out. Note that even with the serial number filled with wax, the leading "0" is almost imperceptible."
Before late 1980, Trek used an alphanumeric serial number scheme. Each seven-character number consists of three letters mixed with numerals. The serial number list and the code for the list are not available from Trek (but hope springs eternal). In the meantime, we have the results of the serial number decoding project:
Nearly two hundred Trek owners submitted their frame's specifics to help decode Trek's first serial number system. Our thanks to these generous cyclists. Trek used this system from 1976 to late 1980.
A = 310 (see note * below) B = TX200 (see note ** below), C = TX300, D = 530, E = TX500, F = 510 (**** see year exception B below), G = TX700 and TX770 (see note*** below), H = 710, I = 730, J = TX900. K = 910, L = 930, M = 412 and 414 (**** see year exception A below), N = 610, 613, and 614 (**** see year exception A below) O = 950. (**** see year exception D below). This numbering system was used for custom 950s. This letter may also have been used for custom 750 frames. If you have a leading O (Oh) serial number on a frame with Reynolds 531 stickers, please contact me (Skip). This applies only to serial numbers in the form LNLNLNN where the first letter is an O (Oh). This does not apply to the all-numeric serial number form that began in late 1980. These begin with a zero not an Oh. For these all-numeric numbers with a leading zero, see LATE 1980 to LATE 1986 below.
A couple of serial numbers have been submitted that are missing the first letter. This letter designates the model. The remaining six characters are typical. It appears that some custom frames were built that did not fit within the standard model description. For example, a 710 frame made with Columbus tubing instead of 531. What leading letter to use? Perhaps it was just left blank?
The second number is the last digit of the year, 6, 7, 8, 9 (for 197X) and 0 for 1980. See note below, ****, for year exceptions. Again, this is the date of serializing, not necessarily model year.
The rest of the code defines time to a month. Perhaps once Trek was nearing more than 2600 bikes/frames of a given model per month, a new serial number scheme needed to be developed. Hence the change to the sequential system that was started in late 1980.
A. Serial numbers beginning with M or N (41X and 61X bikes or frames) seem to have a different meaning for what normally is the year digit. The year digit is the fourth character in the number. In the 50 M and N serial numbers that have been sent in by owners, the year numbers go from 0 through 9. The remaining part of the serial numbers seem normal.
According to the brochures, Trek did not make 41X and 61X bikes or frames during 76, 77, 78, and 79 and also not in 83, 84, 85, 86, 87, 88, or 89. These serial numbers apparently do not follow the year convention used for other Trek models. It is likely these frames, SNs beginning with M or N (Models 41x and 61X), were contracted out or were made in a separate Trek facility, and were given the old serial number form so as not to interfere with the sequential numbers being assigned by Trek in their main shop, which began in late 1980.
This variation to the SN system may have been done to extend the numbering system. By using the fourth character as an extension of the last three, the serial numbers could be extended from 2600 possible combinations to 26,000 for a given month.
B. Serial numbers for four model 510 frames (with a leading F) have been reported that have similar unexpected year dates. (Our thanks to Rich Ferguson, Fred Gomez, and Chris Tank.) The fourth characters are 2, 3, 4, and 5, there may be more. The frames have the early TREK graphics on the seattube. These frames may be related to the M and N leading serial number bikes in the section above.
D. Trek used this form of serial number (leading O "oh") for their custom-made 950 frames. The production (non-custom) frames were numbered using the late 1980 to 1986 system described below. Three (leading O) 950 frames have been reported that contain unlikely year codes of 5, 6 and 7. Model 950 frames were not made in 1975, 76, or 77, but only in 1980, 81, or 82, (according to the brochures). Another 950 frame was reported with a 0 (zero) in the year code, but was painted as a 1982. From the geometries, they all appear to be custom frames.
When a Trek frame was repainted by Trek, an additional set of numerals was often stamped into the bottom bracket to indicate the frame was repainted. These numbers were usually four digits, in the form NNNN.
Late in 1980, Trek changed to a new numbering system for their frames built in the U.S. The frames were numbered sequentially, beginning with number 000001. The record of the assembly runs was documented in a handwritten journal. Trek (Kevin Tita) graciously provided a copy of the journal for this web site. The list ended in November of 1986 with number 279975. This serial number system actually extended through at least 1997 (see Table II below).
The journal includes run number, model number, frame size, and serial number range. Incidental information, including dates and comments on the frames, appears sporadically through the journal. A "run" was for a particular frame size and frame model.
This 6 digit (7 digit beginning in 1993) code extended into at least 1999, at least for some models (generally mid to upper level and made in the US). The number may or may not have a leading zero, making the six digits into seven digits prior to 1993. The model is not available for these numbers but the year can be determined or estimated from Table II below. The information in the table is from serial numbers submitted by site visitors. Our thanks to them. In contrast to the serial number dates in Table I above, the years in Table II represent model years, not the date the serial number was applied.
Three different serial number forms have been submitted for 1983 Trek Model 400 frames. One, marked "made in Japan", begin with JS followed by six numerals. The SN was located on the bottom of the bottom bracket. A second serial number is 81765. According to the Trek-provided SN list, this corresponds to a 22" (22.5") Model 400 frame made in 1983. This SN form is for frames/bikes made in the US The number was marked on the bottom of the bottom bracket. The third number is 403300950, which indicates foreign built, but the nation of origin sticker was missing. This number was marked at the bottom of the down tube. It is likely this 400 was made by the same manufacturer as the 1984 bikes described in the paragraph below. For the 1983 Model 400, it appears Trek used three sources for their frames or complete bikes.
Several 1984 Trek 460s, 420s and 400s have been reported with 9 digit numeric serial numbers stamped on the lower seat tube instead of on the bottom of the bottom bracket. These frames, or complete bikes, apparently were made in Japan by an outside contractor. The numbers submitted are in the range of 401000000 to 440000000.
An 8 or 9 character alphanumeric code was used for mid- and low-level frames subcontracted in Taiwan. Most of these bikes were labeled "Made in Taiwan" (although the sticker often is easily removed). This form of serial number appears to have been used during the period 1987 to 93. The number leads with a T (for Trek?) then a numeral, one letter or two, then five (sometimes 4) numerals. Sean Hickey suggested the first numeral is the year of manufacture, and the letter is the month of the year (A - L). This is confirmed by serial numbers that were submitted by other Trek owners. If there are two letters after the year numeral, the first is the month. The second runs from A through at least Y. It might be a way of extending the 5 digit number series by a factor of 26.
Jazz is a line of foreign-built, entry-level bicycles that Trek sold in the early 90s. (See the history page for a bit more info and the brochures page for a 93 catalog). There seems to be at least three serial number types:
A few owners of early Treks, mostly, from 1976 through the early 80s, report their frames are not marked with serial numbers. A past Trek employee wrote that the police in the Madison and the surrounding area said TREK was famous for bikes with no serial numbers. Seems hundreds didn't get any numbers at all. The serial number guy just missed a few? 2b1af7f3a8