As someone that has crashed a few motorcycles, and also worked in a physical therapy in-patient rehab ward, I would be concerned about a head injury, NOT a body injury. The thing is though, motorcycle helmets are infinitely safer than bike helmets. In fact, your usual bean bucket style of bike helmet is not much protection at all, and offers no protection for the back of your head. My feeling on this is that I will never, ever "take the lane" on a bicycle because it's suicidal (people on their cell phones texting and talking are not "there"), and I ride on the sidewalk and stick to low traffic residential streets. Better to pay a citation than be killed needlessly. So I ride very defensively with full understanding of what happens when a bicyclist meets a car. Usually it's death (if you're lucky) no matter what you're wearing or where you're wearing it. Keep in mind that a motorcycle type helmet will cut down on your ability to hear quite a bit too, and on a bike you need all of your senses to avoid a wreck in the first place.