&gt; Every cyclist I know has a story of unexpectedly ditching.<p>IIRC, the majority of injuries from cycling accidents are to the hands, arms and shoulders.<p>&gt; I personally have cracked a helmet and walked away.<p>Which of course means nothing regarding whether you would have injured your brain.  Our hair, scalps and skulls are remarkably good at protecting our brains.<p>&gt; as good as you are you don&#x27;t control many types of collisions (negligent&#x2F;distracted drivers)<p>True enough, and of course a strike from a two-ton vehicle travelling 20 mph faster than one will impart far more force on one&#x27;s body than a strike of a 180-pound body travelling at 18 mph will impart on the road.<p>Helmets are nothing more than magical safety hats; they&#x27;re placebos; they&#x27;re a triumph of marketing and emotion over reason and sense.  If you wear a bicycle helmet, then logically you should wear a driving helmet, a walking helmet and a sleeping helmet.