&gt; <i>my helmet was cracked by this fall (hit the side of my head on the cement)</i><p>I&#x27;m not sure whether helmets really work, and just to be on the safe side I almost always wear one, but I seem to remember one European biking site -- possibly mentioned here in HN... I forget -- where the author argued that helmets are <i>designed</i> to crack so that it seems they work. But, he argued, whether they crack or not bears no relation to protecting from head injuries; the crack simply leaves you satisfied that the helmet &quot;saved&quot; your life.<p>The article seemed convincing. Sadly I cannot remember where I read it.