Bikes already have serial numbers.<p>It&#x27;s called a frame number, and is stamped into the metal, usually on the bottom bracket (where the pedals connect).<p>At least in the UK, there&#x27;s a police register of stolen bikes using these numbers. It&#x27;s also illegal to buy stolen property.<p><a href="https:&#x2F;&#x2F;www.immobilise.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.immobilise.com&#x2F;</a>