Here in Santa Cruz where meth and heroin are big issues, bikes are a sort of "currency". Most bikes when stolen are mostly parted out and the scrap metal sold or parts sold -- this is at the low to mid-range. For hire end bikes, they are often collected and shipped out of the city (and often times state/country).

While I do a lot to advocate for registering bikes here in town (a group of volunteers I am part of has registered about 300 bikes), the reality is registering doesn't dissuade anything. Here, it gives the cops a tool in case they do find one of the local tweakers with another persons bike.