# Where is the frame number on a Moustache bike? Canonical: https://www.cyclesite.co.uk/trust/frame-numbers/moustache Last reviewed: 2026-06-11 **Quick answer:** The serial number on a Moustache bike usually starts with H and is followed by letters and numbers. On many models, it is behind the seat tube between the motor and rear wheel. On Bosch Smart System and 2023 bikes, check under the down tube near the head tube. Moustache gives clear serial-number guidance. On many Moustache e-bikes, the serial number, also called the chassis number, is behind the seat tube, between the motor and the rear wheel. It begins with the letter H and is followed by letters and numbers. On bikes fitted with the Bosch Smart System and bikes produced in 2023, Moustache says the serial number is under the down tube near the head tube, with a QR code in the same place. ## Check behind the seat tube first. On many Moustache e-bikes the serial number sits behind the seat tube, between the motor and the rear wheel. Newer Smart System bikes move it under the down tube. 1. Put the bike somewhere stable and well lit. 2. Look behind the seat tube, between the motor and the rear wheel. 3. On Bosch Smart System and 2023 bikes, check under the down tube near the head tube, where there is also a QR code. 4. Look for a code starting with H followed by letters and numbers. 5. Check the purchase invoice, which may show the same number. 6. Take a clear photo before typing the number into a checker. ## What a Moustache frame number looks like Moustache gives an example format: H followed by letters and numbers, such as H3EVM08928. The number may also be shown on the purchase invoice. Do not confuse the bike serial with a rear-triangle part number, motor number or battery number. ### Not the frame number - Moustache Samedi - Moustache Dimanche - Moustache Lundi - Moustache Friday - Moustache Xroad - Moustache Game - Moustache Trail - Moustache J - Bosch motor number - Battery serial number - Rear triangle number - Display serial number - Charger number - QR code without matching serial - Model year label ## The rear-triangle number is not the serial Moustache specifically warns that the number on the rear triangle is not the bike serial number. That is an important buyer check. Use the serial number on the frame or invoice, not a removable or replaceable part number. ## Buying a used Moustache 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 Moustache serial number is behind the seat tube, between the motor and the rear wheel, or under the down tube near the head tube on Bosch Smart System and 2023 bikes. Look for the code starting with H, copy it in full, then check it before you buy, sell or register the bike. A used Moustache can be a brilliant buy, but the serial number is the detail that protects you. ## Frequently asked questions ### Where is the frame number on a Moustache Samedi? Check behind the seat tube between the motor and rear wheel. On newer Bosch Smart System bikes, also check under the down tube near the head tube. ### Where is the frame number on a Moustache Dimanche? On Bosch Smart System and 2023 bikes, check under the down tube near the head tube. Otherwise check the frame around the seat tube and motor area. ### Where is the frame number on a Moustache Lundi? Start behind the seat tube between the motor and rear wheel, then check the invoice. ### Does a Moustache serial number start with H? Yes. Moustache says the bike serial number begins with H and is followed by letters and numbers. ### Is the rear triangle number the Moustache serial number? No. Moustache says the rear triangle number is the serial for that part, not the bike’s serial number. ### Can I check if a Moustache is stolen by frame number? Yes. Use the H-prefixed serial number to run a stolen-bike check before buying, and ask for the purchase invoice too. ### How do I register a Moustache bike in the UK? Find the frame number using the locations described above, then record it against your Moustache. 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 Moustache is worth: https://www.cyclesite.co.uk/value/moustache - Stolen Moustache bikes: how to check one before you buy: https://www.cyclesite.co.uk/stolen-bikes/guide/stolen-bikes-by-brand-moustache - Used Moustache prices by model: https://www.cyclesite.co.uk/value/moustache - Used Moustache bikes for sale: https://www.cyclesite.co.uk/bike-brands/moustache - 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/moustache