Trek Bike Serial Number Lookup

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When investing in a quality bike like Trek, you must register your bike on their website, and if you are buying a used model, you can use the same resource for due diligence to make sure the bike you buy is legit – but where do you find the Trek serial number?

To find the serial number on your Trek bike, you need to turn it upside down and let it rest on the handlebars. The bike’s serial number is marked on the underside of the frame, close to the bottom bracket. You can check the serial number using this link to the Trek website.

Trek USA offers an online service where you can look up your Trek Bike serial number or register a new one so that in the event you want to sell yours, buy another one, or yours is stolen, the bike’s relevant information is a click away- so let’s discover more on how to lookup a Trek Bike serial number.

What Information Is Contained In A Trek Bike Serial Number?

In the old days, serial numbers were used mostly to reveal basic information about a product – mostly how many had been made of a model if there was only one.

As more models were made and released, manufacturers began to use serial numbers to provide information on the model type, year of manufacture, the material used, etc. With bike manufacturers like Trek, it became useful to have serial numbers that provided more details about the bike for themselves and the customers.

Trek serial numbers contain information that includes the year of manufacture, the plant manufacturing code, which determines at which facility the bike was made, the day of the year that the bike was made and what number the bike was in the production run on that day.

What The Trek Bike Serial Numbers Mean?

From the early 90s until current, Trek has used the prefix WTU on their serial numbers, with a three-digit number following that and then a single capital letter. Then five digits for the serial number and a final letter to end.

Let’s look at an example and decode what these numbers mean.

For a Trek serial number WTU295D85467D – the serial number would be broken down as follows:

  • After WTU, 295 is the sequential date number from the beginning of the year-so 295 means this frame was made on the 295th day of the year.
  • The 85467 would be the bike’s serial number.
  • The letter D at the end stands for the year 2009, while the letter D after the first three numbers would be the plant where the bike was made.

Based on this configuration and data recovered from a Trek recall notice, we can deduce that the Trek serial numbers use a letter at the end to denote the year of manufacture. With the serial number above, the letter D is the year 2009, and the list below would then represent the years prior and post.

  • D – 2009
  • E – 2010
  • F – 2011
  • G – 2012
  • H – 2013
  • J – 2014
  • K – 2015
  • L – 2016
  • M – 2017
  • N – 2018
  • P – 2019
  • Q – 2020
  • R – 2021

So the very first piece of information on your Trek bike you can identify is the year of it’s manufacture, and you can use this table to determine what year your Trek bike was made.

From the information available, the numbers that follow the WTU and the day number of manufacture, the next letter or group of letters are thought to indicate the manufacturing plant where the bike was made.

Trek themselves aren’t very forthcoming about their serial numbers, only what has been described above. They don’t specify whether the serial number code includes the frame size or material type information.

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Editorial credit: overkit /

Vintage Trek Bike Serial Number Lookup

Trek has been in business for a long time, and many still have vintage Trek bikes dating back to the 1970s. To establish a database of serial numbers and to decode them, a survey of more than 200 Trek owners revealed how Trek serial numbers were utilised on bikes from around 1976 to before the late 1980s.

Here, the serial number configuration was LNLNLNN, where L= Letter and N=Number, so let’s look at the serial numbers and letters and what they would mean on a vintage Trek bike.

The first letter is the frame model, and the first number is the frame size. So if the serial number begins with A1, the A would represent the Frame model 210, and the one would define a 19.75″ frame.

The letter after that represents the month the frame was serialized, so A would mean January, B would be February, etc.

The second number represents the last digit of the year of serializing and is not a reference to the year model. The final three places of the serial number have letters from A through Z and numbers from 01-99.

The letters are thought to relate to the run’s designation, and the last two letters could relate to the frame number in that run. As an example, if the serial number on your Trek bike were D5F8J57, then that would tell you the following :

  • D- Frame model 510
  • 5 –  25,5″ frame size
  • F – The month of serialization would be June
  • 8 –  1978 is the year of serialization
  • J – Designating the 10th run
  • 57 – the 57th frame of the run

You can see the complete serial number survey with all the various models and exceptions here, so you can get some info using this reference to look up your vintage Trek bike serial number.


It seems odd that such a prolific manufacturer of arguably the world’s best bicycles offers no concrete information on the structure of its serial numbers, and while the registration and recovery service is a plus, submitting a Trek serial number on their website will give you a good idea of your bike and it’s history.

Since not every bike owner is interested in decoding their Trek serial numbers and only concerned with registering their bike in case it gets stolen or needs basic information, this could be why Trek hasn’t released detailed information on their serial numbers yet.


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