Bingo, we have a winner. Collectivists who put the interests of many ahead of the few put their 'stripes' on display for all to see. In defense of the country this would manifest itself in the form of a draft. However, during a time of national crisis, volunteers would be numerous enough to make forced enlistment unnecessary (and among a freedom enjoying populace, unthinkable). Think of cycle riders as mere draftees in the state's plan to institute their vision of a greater good. A win-win for the State, those who might have chosen to voluntarily wear a helmet may figure that the state has made this choice for them.
As is demonstrated ad nausium by the poster of this thread.