"It's a movement, not a moment." That's the mantra from Sam "Coach" Balto, a former school teacher from Portland, Oregon who quit his day job to stoke a revolution called the "bike bus" groups of kids and families cycling to school together. How did one person in a mid-sized American city turn a weekly bike ride into something of a phenomenon? He leaned on the power of social media. In the past two years his videos have been viewed by hundreds of millions of people. In Portland, a "bike train" movement kicked off in 2010 when a 24-year-old bike advocate named Kiel Johnson began organising what he referred to as "bike trains" at an elementary school, where riders would join a mass of cyclists at various stops along a route to school. It caught on and in just a few months Johnson had signed up six other schools, won a grant, and had been interviewed by a national television show. "When you joined one of the big bike trains it really felt like you were part of something," Johnson recalls. The children loved it, and why wouldn't they? It's good for children's health " mental and physical " and also has a ripple effect of advantages for the whole family, as any Dutch person will argue. Many of Balto's students say the best thing about the bike bus is that it's simply a cool thing to do with friends. In the past year alone, Balto's videos have been viewed more than 200m times. Balto, who now runs the nonprofit Bike Bus World, credits social media for building the movement.