I like the implanted chip idea, but I predict it won't take the "bums on bikes" long to figure out where they are and disable them. The impromptu chop shops that line our back streets with dead RV's will spray paint them for ten bucks, courtesy of sign holders that many of us sympathetic types hand money to.  And I predict that persons renting them won't lock them up, since they have no skin in the game.  They will all be stolen in a month, spray-painted with primer, and eventually, tossed into the Amazon Canal, along with all the shopping carts. I hope I'm wrong, but remember, Donald Trump is now ahead! Ours is a nation of trash, both material and human.