YBike and SF Bicycle Coalition present a Learn-to-Ride workshop, to help every child master the skill of riding a bicycle. YBike instructors assists new riders to get rolling, based on each child's ability. YBike also helps biking children improve their skills, by practicing turns, stops, and hand signals. Bikes of all sizes and equipment are provided (or bring your own bike). Helmet giveaway while supplies last!  A neighborhood family ride follows the workshop at 1:30PM. This Safe Routes to School-sponsored event is…