Carbon Fiber Motorcycle Helmets are the strongest made helmets you can get. Technological updates that are constantly occurring are taking this material and making it better and better each time. Carbon fiber Motorcycle Helmets may cost more than their plastic or fiberglass counterparts, but they're worth the extra money. It's your head, your brain, so you make the choice which material you want wrapped around your head. However, the material used in helmet making is only as good as the the rest of the construction of the helmet. You can have a great material, but the manufacturer will wrap that material around the foam required for a DOT rating, and when all this comes together is when the helmet is complete and ready for the road. 

Carbon Fiber novelty helmets are made of this great material, but the carbon fiber alone does not make them safe for road use. The absence of the foam inside, which is typically replaced with a 4x4 piece of foam(for comfort purposes only) and then overlapped with a lining to make the helmet as comfortable as possible, but still by no means necessary, is it safe to ride with.