Actually, purchasing stolen goods is illegal in most places, full stop. The reason is that it's practically impossible to prove beyond a reasonable doubt what somebody did or didn't know, and when.

The BikeID idea is about as old as bike theft, but it's pretty difficult to enforce. If you care enough about not buying a stolen bike, the solution is simple: Ask for the original invoice. If not, you're not going to bother looking up the bike.

You could sweep parking areas, but you'd only return the bikes to their owners, at considerable cost to operate - and buying a stolen bike is still free of risk of punishment.

> Actually, purchasing stolen goods is illegal in most places, full stop.

In my state, the statute says "such person knowing or having reasonable grounds to believe the same to have been feloniously stolen or taken".

I doubt any state makes receiving stolen goods in complete ignorance a crime. However, the stolen goods are generally recoverable by the original owner, whether or not the person receiving them purchased them in good faith.

And the "reasonable" is in regard to the legal reasonable person, not to the individual in question, so "I just thought it sounded like a really good deal" isn't really a defence (that's how we spell it here) unless you had equally reasonable grounds to believe that the deal was square. If there's one really cheap bike at what appears to be a yard sale, you're probably okay, but if there are ten of them, well, you're legally expected to be at least a little suspicious.

>However, the stolen goods are generally recoverable by the original owner, whether or not the person receiving them purchased them in good faith.

This is good. Usually there is just a demand for bikes. With this system there will be a demand for non-stolen bikes. The prices for stolen bikes go down and so does stealing them.

> "The prices for stolen bikes go down and so does stealing them."

If the buyer did not know the bike was stolen, this will only punish the buyer and have no effect on the price of bicycles, since one cannot distinguish between a stolen vs. non-stolen bike (short of, say, suspiciously low prices, which has been called out elsewhere in this thread as a non-issue).

As usual, it's probably more complicated than that…

I wonder how much the "market price" for 2nd hand bikes is driven by the large(?) volume of stolen bikes in the market? Are legitimate bike sellers being forced into selling at lower-then-desired price points by a glut of stolen bikes being offered for 15 or 20% below "current prices", perhaps over time settling on unrealistically low market expectations? I wonder how big a percentage of the total demand for 2nd hand bikes is being met by the supply of stolen bikes? And what the effect of removing the stolen portion of the supply would be on the market price?

It's possible that if you raised barriers against selling stolen bikes, the prices of legitimate 2nd hand bike would rise, creating a "gap" where the time and money customizing/disguising stolen bikes became worthwhile.

Why would a purchaser, after paying, ever check a stolen registry? So they can add themselves to the list of victims as well?

Pre-transaction diligence is workable, post-transaction checks are a non-starter.

Just to avoid getting into legal trouble, for starters.