I've riden in enough high crime areas (see south central LA) to know to leave sacrificial items on a parked bike. In 30 years I have had one cheap Cateye bike computer stolen (LA) and one tire slashed (Denver Federal Center). Let them steal the water bottles, I find new ones free on the road side. Like most others I lock the helmet along with the bike. The only dorks are cyclists without helmets. I avoid them like I avoid cars with three different colors of body panels.