I don't know about where you live, but in Iowa about 80% of the bicyclists I see wear helmets, and about 5% of the motorcyclists I see wear helmets. On RAGBRAI, helmet use is more like 99%. When I consider which rider is at greater risk in case of an accident, it just seems nutty to me. My husband and I refer to them as smart motorcyclists (the few with helmets) vs. organ donors (those without). Iowa had a mandatory helmet law in the past, but big time lobbying from bikers got that changed. So, a part of the motorcycle culture in this state has to do with demonstrating their "freedom" to ride with a bare head. Personally, I'm glad that helmet use is cool for cyclists.