Guide
Where is the serial number on a Trek bike?
On Trek bikes, the serial number is on the bottom bracket near the crankset: underneath the bike, near the pedals. That is what Trek says in its safety notices, where it explains to owners how to identify their bike. On the bikes in a 2025 notice, the number begins with WTU. Trek also asks you to write the number in its manual and register the bike, because it matters if the bike is stolen.
By the destolen team · Reviewed on 27 October 2026.
Step by step
Look underneath, near the pedals
Lay the bike down or turn it over and look at the bottom bracket near the crankset: that is where Trek places the serial number in its safety notices. If it is dirty, clean it before reading it.
Read all of it
Copy every letter and number in the same order. On the bikes in a 2025 Trek safety notice (some Precaliber and Electra Sprocket bikes), the number begins with WTU. Trek does not say in the sources we checked that all its numbers start that way, so do not rule a number out just because it starts differently: compare it with the receipt.
Write it in the manual
The Trek owner’s manual (revision of March 2026) asks you to record the serial number in the manual itself, keep the manual somewhere safe and register the bike online.
Photograph it and register it
Take a close-up photo where the number can be read and another showing where it is on the frame, and keep them with the receipt. Register your Trek for free on destolen (up to 5 bikes) with the number and the photos: if it is stolen, you will have everything to hand for the police report.
Before buying a used one, check it
If you are buying a Trek second-hand, ask to see the number on the frame (not just in a photo) and type it into the destolen checker: it is free and you do not need an account. If it is reported stolen, do not buy it and tell the police. If it is not, that only means it does not appear in the sources checked.
Check a bike by its serial number
What Trek says
In a 2025 safety notice, Trek tells owners that their bike’s serial number begins with WTU and is located on the bottom bracket near the crankset, underneath the bike near the pedals. A 2023 notice also places it on the bottom bracket near the crankset.
In its owner’s manual, Trek recommends registering the bike, because registration records the serial number, which is important if the bike is ever lost or stolen, and writing the number in the manual.
In the sources we were able to open, Trek does not give other locations for its current models. If you cannot find it at the bottom bracket, check the usual places explained in our general guide.
If the number is worn off or you cannot find it
If it is your bike, look for the number on the receipt or in your Trek registration, or ask the shop where you bought it, with your proof of purchase.
If you are buying a bike and the number has been filed off, scratched, painted over or the label has been torn off, do not buy it: it is a red flag. You can tell the police and give them the link to the listing.
Other brands
Frequently asked questions
Do all Trek serial numbers start with WTU?
We do not know for sure. Trek says they begin with WTU on the bikes in a 2025 safety notice, but not that this applies to all its models. If yours starts differently, compare it with the receipt.
Where should I write it down so I do not lose it?
Trek asks you to record it in the owner’s manual and to register the bike. Also take a photo and keep it in your free destolen registration.
Sources checked on 27 October 2026
Have your bike's details ready
Register your bike for free with photos and serial number: if it is stolen, you will have everything at hand to report it and search for it. And before buying a used one, check its serial number.