IME, everything--that is not SECURELY fastened down--will fly around the passenger compartment during a rollover, and it will seem afterwards that most of it hit you on the head. I don't have very much loose in the car, anymore. Where I can't get a good hookup with a seatbelt, I use 1" tubular webbing, and carabiners to hold my bag. As far as motorcycles go, if you're not willing to land on it, at speed, don't wear it.