If these are effective they would be great partnered with the urban bike share programs that don't include helmets. I love that the programs cut down on traffic and allow tourists to see a city or residents to bike for a portion of the day without riding a bike to and from work. But I hold my breath when I see bike sharers riding bare-headed, and I won't join because I'm not going to carry a helmet around. These could be rented with the bike if they are adjustable to different sizes. Interesting.