in the motorcycle industry they used to have a disc lock that was an alarm as well. since the bicycles are using disc brakes, something like this may come in handy. when the locks are moved around the alarm goes off. i don't know it they are still being made, but if they are, it might be something to check in to just to prevent situations like this from happening. sorry to hear about the bad luck, hope all the bikes return home safely

nojzilla- your comment about the brain still moving is spot on. 10 years ago I wrecked my motorcycle. Ended up breaking C2, and my helmet came over and busted my left collar bone. Anyways, on the top of my helmet, there is a dent. Not a scratch, but a dent. No marks on the top of my head, but on my CT scans at the hospital, there was a nice big black spot on my brain. Neuro doctor informed me that was a bruise my brain suffered due to impact with the top of my skull.

they say that it's the edges of the full face around the bottom. in certain situations it can add pressure when your neck is trying to bend or compress. there are/were actually groups of people trying to get rid of (motorcycle) helmet laws because they say it increases the chance of spinal injury. i was wearing my full face when i wrecked my motorcycle. ended up with a broken neck AND traumatic brain injury. a helmet can't stop everything, but i'd be dead if it weren't for mine. ironically, i still can't get my oldest son to wear a helmet when he's riding his skateboard/bicycle. wife says it his choice, even after 2 concussions and once knocked out in the middle of the street.