Phoenix law currently requires helmets for under-18s.

Let's make sure a Bike Share program doesn't require helmets of over-18s.

Here's an argument why, from the cited article: "“Pushing helmets really kills cycling and bike-sharing in particular because it promotes a sense of danger that just isn’t justified — in fact, cycling has many health benefits,” says Piet de Jong, a professor in the department of applied finance and actuarial studies at Macquarie University in Sydney. He studied the issue with mathematical modeling, and concludes that the benefits may outweigh the risks by 20 to 1."