For the first 17 years or so of Surly, we just asked that you keep your original receipt for your bike. That will serve as proof of purchase and make it easy to get things going. But hey! What’s this? We actually have online registration now. Who knew? We’ll keep your information in the sort of private way you’d want us to, and that will mean we have your serial number and other pertinent information on file. We might need that for a warranty, or to contact you if there’s a recall or some such. You might need it if your bike is lifted and you didn’t write down the proper digits. Everyone wins. So fill that sucker out. Thanks.