# Where is the frame number on a Serial 1 bike? Canonical: https://www.cyclesite.co.uk/trust/frame-numbers/serial-1 Last reviewed: 2026-06-11 **Quick answer:** Serial 1 says each bike has one main frame serial number, plus other serial numbers for parts and components. Use the general bike frame serial number for ownership, insurance, support and stolen-bike checks. Serial 1 e-bikes can have several serial numbers, but the one that matters most for ownership is the main bike frame serial number. Component serials may identify parts, but they do not replace the frame serial. If you are buying used, ask for the frame serial number, not just a motor, battery or charger number. ## Start under the bottom bracket. This is the most common place to find a Serial 1 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 - The original purchase paperwork or dealer record. - The Serial 1 registration or support record. ## What a Serial 1 frame number looks like Use the full frame serial number exactly as shown on the bike and paperwork. Serial 1 support guidance says specific digits in the frame serial can even identify the bike’s generation. Do not use a battery, motor, charger, display or component serial as the bike frame number. ### Not the frame number - Serial 1 Mosh - Serial 1 Rush - MOSH/CTY - RUSH/CTY - RUSH/CTY SPEED - BASH/MTN - Harley-Davidson badge - Battery serial number - Brose motor number - Charger number - Display serial number - Controller number - Wheel serial number ## One frame serial among many part serials The key Serial 1 issue is multiple serials. The bike has a main frame serial number and separate part serials. For ownership, insurance and stolen-bike checks, use the main frame serial number. ## Buying a used Serial 1 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 Serial 1 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 Serial 1 can be a brilliant buy, but the frame number is the detail that protects you. ## Frequently asked questions ### Where is the frame number on a Serial 1 MOSH/CTY? Use the main bike frame serial number, not the battery or component serial. Check the frame and original paperwork. ### Where is the frame number on a Serial 1 RUSH/CTY? Ask for the general bike frame serial number and match it with proof of purchase. ### Is the battery number the Serial 1 frame number? No. Serial 1 says the bike has several serial numbers, but the frame serial is the main bike identifier. ### Can the Serial 1 frame serial tell the generation? Yes. Serial 1 says specific digits in the frame serial can help identify whether the bike is first-generation or current-generation. ### Can I check if a Serial 1 is stolen by frame number? Yes. Use the main frame serial number to run a stolen-bike check before buying, and ask for proof of purchase. ### How do I register a Serial 1 bike in the UK? Find the frame number using the locations described above, then record it against your Serial 1. 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 Serial 1 is worth: https://www.cyclesite.co.uk/value/serial-1 - Stolen Serial 1 bikes: how to check one before you buy: https://www.cyclesite.co.uk/stolen-bikes/guide/stolen-bikes-by-brand-serial-1 - Used Serial 1 prices by model: https://www.cyclesite.co.uk/value/serial-1 - Used Serial 1 bikes for sale: https://www.cyclesite.co.uk/bike-brands/serial-1 - 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/serial-1