An invisible bike helmet sounds like yet another cool concept. But this is actually a real product you can buy today. Two women took their idea from their master thesis and worked on it over 7 years. The Hövding (English: Chieftain) is a collar for bikers, worn around the neck. The collar contains a folded up airbag that you'll only see if you happen to have an accident.
The airbag is shaped like a hood, surrounding and protecting the bicyclist's head. The trigger mechanism is controlled by sensors which pick up the abnormal movements of a bicyclist in an accident.
The invisible bike helmet sets you back 3998 SEK (~$600). I am not sure if the invisible bike helmet will take off. You still have the wear this big collar.