By popular demand, here is the City of Cyclists video showing bicyclists in Copenhagen!
Most cyclists in Copenhagen do not wear helmets, yet fatalities on a per rider basis are much lower than in the United States. The Danish are concerned that requiring bike helmets would only discourage cycling. In Copenhagen, 36% of all commuting trips are by bike. The more bicyclists there are, the more drivers learn to expect (and respect) them.
Unfortunately, the Maryland General Assembly is considering a bill that would require all cyclists to wear helmets. This would surely kill BikeShare in Montgomery County as well as reduce the level of bike use overall, especially trips to transit.