# Where is the frame number on a Trek bike? Canonical: https://www.cyclesite.co.uk/trust/frame-numbers/trek Last reviewed: 2026-06-11 **Quick answer:** The frame number on a Trek bike is usually underneath the frame, close to the bottom bracket between the pedals. Look for a stamped code or a barcode sticker with a long mix of letters and numbers. On many Trek bikes the number starts with WTU. Most Trek bike frame numbers are found underneath the bike, near the bottom bracket. That is the part of the frame where the pedal cranks meet. Turn the bike carefully upside down, look between the pedals, and check the underside of the frame. On many modern Trek bikes the serial number is printed on a barcode sticker. It is usually a mix of letters and numbers, and many Trek serial numbers begin with WTU. ## Start under the bottom bracket. This is the most common place to find a Trek frame number. It is the part of the frame between the pedals, on the underside. 1. Put the bike somewhere safe and well lit. 2. Turn it upside down carefully, or place it in a workstand. 3. Look underneath the frame where the cranks meet the bike. 4. Wipe away mud, grease or road dirt. 5. Use a phone torch if the number is hard to read. 6. Take a clear photo before typing the number into a checker. ### If it is not under the bottom bracket - Near the rear dropouts, where the back wheel fits into the frame. - Around the seat tube. - On the underside of the down tube. - Near the head tube at the front of the bike. - On the original sales receipt. - In your Trek registration email or paperwork. - With the Trek dealer that sold the bike. ## What a Trek frame number looks like A Trek frame number is normally a string of letters and numbers. On newer Trek bikes it is often printed on a sticker with a barcode. Many start with WTU, followed by more letters and numbers. ### Not the frame number - Trek Domane - Trek Marlin - 700c - 29 inch - Shimano part numbers - Wheel serial numbers - Shop stock labels ## Buying a used Trek A clean-looking bike is not always a safe buy. Before you pay, ask the seller for a clear photo of the frame number and check it against stolen-bike records. You should also ask for: - The original receipt or proof of purchase. - The seller’s name matching the receipt where possible. - Clear photos of the bike from both sides. - A photo of the frame number. - Any service history. - Details of upgrades or replacement parts. ## Bottom line The quickest place to find a Trek frame number is underneath the bike, near the pedals. Look for a stamped code or barcode sticker, copy the full number, then check it before you buy, sell or register the bike. A used Trek can be a brilliant buy, but the frame number is the detail that protects you. ## Frequently asked questions ### Is a Trek frame number the same as a serial number? Yes. Most people use frame number and serial number to mean the same thing. It is the unique identifying code attached to the bike frame. ### Do all Trek bikes have a frame number? Most Trek bikes have a frame number or serial number. Check the locations described above first; on older frames the marking can be shallow or worn, so clean the area and check in good light before concluding it is missing. ### Where is the frame number on a Trek Marlin? On most Trek Marlin mountain bikes, check underneath the bottom bracket first. That is the area between the pedals on the underside of the frame. ### Where is the frame number on a Trek Domane? On most Trek Domane road bikes, look underneath the frame near the bottom bracket. You may find a barcode sticker with the serial number printed on it. ### What if the Trek frame number has been removed? Do not buy the bike. A removed or damaged frame number is a major red flag. It may make the bike harder to register, insure, resell or prove as yours. ### Can I check if a Trek bike is stolen by the frame number? Yes. Use the frame number to run a stolen-bike check before buying. You should also ask the seller for proof of ownership and check that the details match the bike. ### How do I register a Trek bike in the UK? Find the frame number using the locations described above, then record it against your Trek. It is free, and you need an account so we know where to send the alert. If that exact number is ever reported stolen to us, we email you. If anyone then lists a bike carrying it, the listing is hidden until the seller proves it is theirs. ## Related pages - Free stolen-bike check: https://www.cyclesite.co.uk/stolen-bikes - What a used Trek is worth: https://www.cyclesite.co.uk/value/trek - Stolen Trek bikes: how to check one before you buy: https://www.cyclesite.co.uk/stolen-bikes/guide/stolen-bikes-by-brand-trek - Used Trek prices by model: https://www.cyclesite.co.uk/value/trek - Used Trek bikes for sale: https://www.cyclesite.co.uk/bike-brands/trek - Alternatives to Trek and how they hold value: https://www.cyclesite.co.uk/bike-brands/trek/alternatives - Cube vs Trek: https://www.cyclesite.co.uk/compare-bikes/cube-vs-trek - Trek vs Specialized: https://www.cyclesite.co.uk/compare-bikes/trek-vs-specialized - Giant vs Trek: https://www.cyclesite.co.uk/compare-bikes/giant-vs-trek - Canyon vs Trek: https://www.cyclesite.co.uk/compare-bikes/canyon-vs-trek - Trek Domane vs Specialized Roubaix: https://www.cyclesite.co.uk/compare-bikes/trek-domane-vs-specialized-roubaix - Specialized Tarmac vs Trek Emonda: https://www.cyclesite.co.uk/compare-bikes/specialized-tarmac-vs-trek-emonda - Frame numbers for other brands: https://www.cyclesite.co.uk/trust/frame-numbers Source: Cyclesite editorial, reviewed 2026-06-11. HTML version: https://www.cyclesite.co.uk/trust/frame-numbers/trek