Making the bike as ugly as possible is why I mentioned the cheap used bike.

Difference between stealing a car and a bicycle is that with a car it's grand theft due to the value, a bike is not as valuable as a car thus the police dept's will never seriously go after bike thieves, and when they do catch them it's never grand theft unless their caught with a bunch of bikes. Grand theft is determine by wholesale value of said item on the market, you could have a $3,000 bike but if it's 3 or 5 years (or more) old it may not be worth more then $250 wholesale. Most stolen bikes are stripped of parts and the frame repainted and sold or scrapped for junk value. Some stolen bikes are ridden for a short distance then ditched, those sometimes are recovered. Of all recovered bicycles only 5% of them ever find their rightful owners! Why is that? The owner has no proof, no receipt, no model registration number either in hand when they go to claim it or never given to the police at time of loss so the police have no way of knowing whose bike it is.

Bicycle thieves are actually more difficult to track as well due to no registration of said bike, none of the parts are numbered, anyone will buy it and no one would know it was stolen. The only way to protect yourself, and this is extremely limited in the protection it offers is to have the registration number of the bike recorded somewhere, the year make, model, and color, description of accessories, where you last saw your bike and when. But even with that info recovery is slim to none. What makes it more frustrating is that a lot of large cities won't even waste their time taking a report on a stolen bike!! So if you have home or renters insurance your screwed because you don't have a report, you might be able to get a reference number telling you that you reported the incident but no official report; make sure too you have the reporting officer's name, badge and contact info. Most people who own bikes have not written down and have no idea what the bike's ID number is, so most are screwed right from the start.

The model registration problem is why I think there should be a one time fee on all new bikes sold of $25 that registers the bike on a state data base system so if a bike should be stolen it can be quickly checked to see who owned the bike at registration time. The only time the fee would have to be reapplied for is if you sell the bike and the new owner wants to transfer the title to their name. Also the $25 fee would be optional for anyone who has a current bike and wanted to make sure it was registered for protection. That money could then be used for bike infrastructural improvements.