Gt Bike Serial Number Decoder

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Gt Bike Serial Number Decoder Average ratng: 10,0/10 9614 reviews

The last frame number appears to be GT750-80508 belonging (at the time of writing) to Bjorn in Scandanavia. The highest engine number Martin Krause of the Wasserbueffel Club in Germany has recorded so far is GT750-87388 and he also notes that the machine in the Suzuki museum in Japan is frame number GT750-80507. The bike and frame is old, got be 15 years old+ The frame has the following features: There is a GT Logo stamped on the frame by the Saddle There is a serial number stamped at the bottom of the rear forks 09935711 Sticker on Frame reads Heat Treated Aluminimum 6060-T6 I have some pictures here which show the welds, sticker and serial number.

Trek Frame Serial Numbers

Prior to Late 1980 Late 1980 to Late 1986 Late 1986 to 1999+
Foreign Built After 82 Jazz by Trek Missing Serial Numbers

Serial Number Location

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.

Note: The SN on your original sales receipt may not match the one on your bike. Sales persons sometimes had difficulty reading the numbers.

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.

Serialization Date

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.

Hard to read?

Trek serial numbers can be hard to read. Clean the area well, and use lots of light at various angles. A suggestion by J. Hansen can help you read a serial number:

Serial Number highlighted with red wax. Click on image to see an enlarged version. (Photo by J. Hansen)

'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.'

Serial Number Descriptions

The serial number descriptions are divided into five categories. Click on the link below to go to the appropriate category.

Prior to Late 1980 Late 1980 to Late 1986 Late 1986 to 1999+
Foreign Built After 84 Jazz by Trek Missing Serial Numbers


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:

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 variant of this first system was used in 81 and perhaps 82 for some frames. See **** year exceptions below.

These serial numbers have seven characters, in the form L N L N L N N, where L is a letter and N is a number.

Here are the results:

The first letter is the model designation. The letter code indicates frame model, which would include bike models made from that model of frame.

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 first number is the frame size, where

1 = 19.75',
2 = 21',
3 = 22.5',
4 = 24',
5 = 25.5',
6 = 57.5 cm (ctc) or indicates a custom size. (See Year Exception D.)
7 = 59 cm (ctc) or indicates a custom size. (See Year Exception D.)

9 = 63.5 cm (ctc) or indicates a custom size. (See Year Exception D.)

The second letter represents the month the frame was serialized:


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 last three characters - The final letter ranges from A to Z and the final two numbers go from 01 to 99. The last letter might be a run designation, with the last two numerals the frame number in that run? Alternatively, the letter extends the range of the character from 0 to 9 (if a number) to 1 to 26. This gives a range of 2600 for the 3 characters. Any other ideas for these last three characters?

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.


* There is no Model 310 in the brochures on the site; however, a frame has been reported that has Ishiwata high tensile double butted main tubes with the SN A4F9H67. It has touring length chainstays. According the the SN, it apparently was made in June 1979, after the TX300 is no longer in the brochures, but no similar frame is listed. Another small mystery; for now we'll call it a 310.

** One interesting variant of the SN code has been submitted. It has a leading B and has eight characters instead of the usual 7 (B4K6B109). It has SunTour dropouts, and had a partial tubing sticker that included the text 'TENSION BUTTED'. The date from the SN is Nov. 76. Probably a TX200 with an extra character in the SN.

*** Several frames with a leading serial letter of G have been reported with Columbus tubing stickers. TX700 frames were available as special order, with Columbus tubing instead of the specified Reynolds 531. These bikes were designated as Model TX770. However, this model did not appear in any of the Trek brochures on this site.

****Year Exceptions:

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.

For M and N leading serial numbers, if the TREK letters on the seattube have no colorwrap behind, the bike is from 1980 or perhaps 1981. If it has a colorwrap, the bike is probably from 1982.

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.

C. One early TX700 (leading G), an evaluation frame sent to a bike shop, had a 4 in the year digit. Another impossible year code. This 4 may signify an evaluation unit.

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 1980 TO LATE 1986

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.

We all owe thanks to Luker White who generously donated his time to convert much of the paper list to digital form.

These data were mined to produce bike production by model for each calendar year. The results can be seen on the Trek Bike Production by Model, Late 1980 through 1986 page.

Click on the date link in Table I below to go to the detailed serial number information for that year.

Table I - 1980 to 1986

Beginning Serial Number

Notes for Table I:

  1. Table I contains dates of frame serializing, and are not necessarily model year. At some time late in each year (generally September or October) frames were built for (then painted with colors for) the next model year. This journal information is summarized by year in Table I. The year designations in the table are approximate; not all of the runs are sequential in time. This may be a result of subcontracting some frame fabrication.
  2. 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. 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.
  3. Some of the Model 170 serial numbers are 6 digits but do not follow the numerical sequence. A future task is to sort 170 numbers. Some of these are presented in the 83, 84 link at the bottom of the table.
  4. Some early and mid 80s bottom brackets were marked with 58TSI or 60TSI. In the early 1980s Tim S. Isaac designed new lugs and a new bottom bracket shell for Trek. The new bottom bracket shell is typically marked with 58TSI (or more rarely, 60TSI). This designation is not part of the serial number but is a model number of the shell. The TSI are Tim's initials. The 58 or 60 refer to the angle between the seattube and the downtube.
  5. Some frames in this period have a leading 'A' before the 6 digit number. This may be more prevalent on lower level models. The 'A' may not be part of the SN. Just disregard it when looking up the number in the tables below.
  6. Frame Sizes in the SN list below are as given on the paper copy. For some entries, only a two-digit number was given, the extra 1/2 or 3/4 inch was dropped. So - an entry of 22 inches really means a 22.5' frame size, 19 means 19.75', 25 means 25.5'.
  7. The list has two major gaps, corresponding to missing pages. Page 9 ends with SN 027870 and the next page starts with 029118. Page 61 ends with 210065 and the next page starts with 215226.
  8. The SN list for 1986 has some serial number ranges with annotations about POs (purchase orders) to 'Merida'. These are for Model 800, 830 and 850 mountain bikes and Model 300 road bikes. These were made late in the year, so they probably were all 1987 models. At least some of these were provided to Trek as 'frames only'. One reported SN in these ranges, for an 850, was prefaced by the letters TML. From the serial number list, the number of Trek frames or bikes made by Merida late in 86 totaled at least 8251.
    Merida is a Taiwanese bike company that was established in 1972. It is currently a major, worldwide player in the bicycle business. See for information on this company.

    LATE 1986 to 1999+

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.

Gt performer serial number decoder

    Table II - Model Years 1987 to 1999

Serial Numbers Include
270821, 284237, 284335, 293788, 301294, 304445, 304940, 307880, 308292
309634, 316981, 319336, 335133, 346451, 347944, 356837, 360384, 364072
369203, 379079, 391236, 406793, 427402, 438108, 455267
458184, 513747, 532881, 563678
579529, 629426, 653761, 669753, 740528, 79xxxx
771408?, 811550, 819194, 840762, 873805, 883719, 900224
971670, 1027164, 1035688, 108?734, 1106529, 1109196, 1116394, 1125523, 1125738
1164917, 1269067, 1287883, 1306226
1331934, 1383671, 1406630, 1431480, 1439467, 1506862
1544446, 1649278, 1878372, 1955570
1876296?, 1963294, 2008374, 2063546
2090413, 2140321, 2172336, 2195013


  1. 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.

  2. 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.

  3. 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.

  4. A later 8 and then 9 character alphanumeric SN scheme, used beginning in about 1989, also begins with a T (for Trek?). These later T numbers were used on lower level subcontracted frames but do not follow the 2nd and 3rd or 3rd and 4th character date meanings above.

  5. Beginning in about 1993 (model year 94), an 8 character alphanumeric code was used for some bikes. It begins with G and another letter (e.g. GN, GQ, GR, GS, GU, GV, GW, GY and GZ). These are followed either by: 6 numerals, or a numeral and a letter followed by four numerals. The first numeral in the SN may be the year of serialization.


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:

  1. A Flipside model had the serial number JT0116 stamped on the bottom bracket shell. The JT probably stands for 'Jazz' and 'Trek'. The numbers may be the sequential frame number, beginning at 0001.
  2. The second type is a 10-character serial number. The first two characters are letters which are followed by eight numbers. Examples are JT09010099 and FI08003231.
  3. A Latitude model has a 10-digit, all-numeric serial number: 1230707859. This number also was stamped on the bottom of the bottom bracket shell.

Gt Bicycle Serial Number Decoder

Gt bike serial number decoder

These three serial number forms may mean that Trek used at least three subcontractors for the Jazz line.


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?

Three other possibilities: 1. In the early years Trek allowed, and even encouraged, their workers to use company equipment and materials to build personal frames after hours. These frames often were not serialized. The practice stopped after production was increased, resulting in little available down time for the equipment. 2. The serial number on a repainted frame that was not first stripped, may disappear under the new paint. 3. The number is under the plastic cable guide attached to the bottom of the bottom bracket shell.

Prior to Late 1980 Late 1980 to Late 1986 Late 1986 to 1999+
Foreign Built After 82 Jazz by Trek Missing Serial Numbers

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All materials in this site not copyrighted by others are Copyright © 2001-2015 Skip Echert Web Associates, All rights reserved.

How Old is My Bike?

Unfortunately, exactly dating a Peugeot earlier than the late 1970s is an art rather than a science, and is often an estimate at best. Even original owners have a hard time remembering the year that they purchased the bicycle. That said, it is possible to date a bike within a couple of years with some confidence based on frame features and components. See the 'Frames, Headbadges and Decals' webpage for a pictorial timeline of frame features, and the 'Parts & Accessories' webpage for information on when specific components were found on 'U' bicycles.

Gt Mountain Bike Serial Number Decoder

Older bicycles have a serial number on the underside of the bottom bracket. If the number has six digits the frame was probably made in the 1960s, seven digits in the 1970s. Sometimes, the first digit indicates the year within each decade that the frame was made. For example, 1940481 and 2400884 represent 1971 and 1972, respectively. However, there are many cases when the first digit suggests a frame production year that is older than the actual age of the bicycle. For example, the serial number 1355592 on a 1975 bicycle. The reverse has not been documented, so it is likely that bicycles are no older than the first digit in the factory serial number, but could be younger. Sometimes local bike shops etched serial numbers into the rear dropout, but this number may or may not match the original.

1971 UO8 Serial Number Plate 1972 AO8 Serial Number Plate 1973 UE18 Aftermarket Dropout Serial Number Late 1960s UO8 Aftermarket Serial Number
Photo by Greg Carps - Original OwnerWebmaster's AO8 Photo by Mark Kaczmarczyk

It is helpful to compare the serial numbers of older bicycles with dates that are sometimes found on the rims, hubs and derailleurs. Although my 1972 AO8 has DEA rims and a Simplex Prestige rear derailleur clearly marked '1972' and '72', respectively, these dates also cannot be used alone to determine the age of a bicycle. For example, my 1973 UE8 came equipped with a 1971 derailleur. If your serial number and component dates match, you are probably in good shape. If not, the bicycle is no older than the latest component, but you will have to estimate the age (e.g., early 70s).

Gt Bikes Serial Number Decoder

1970 Simplex Prestige 537 Derailleur1971 Simplex Prestige 637 DerailleurUnderside 1971 Simplex Prestige Front Derailleur1975 Chrolux Rim1972 DEA Rim
1975 Wide-flange Normandy Hub