By Martyn Herman LONDON, March 4 (Reuters) - Sarah Hammer was racing around velodromes when her U.S. pursuit team mates were still on tricycles and she used all that experience to guide them to world championship gold on Friday. The 32-year-old had already slipped on the rainbow jersey seven times in a dazzling individual career, but at the London velodrome she had some company on the podium. Kelly Catlin, 20, Chloe Dygert, 19, and 21-year-old Jennifer Valente all produced brilliant rides too against Canada as the U.S. celebrated a first world title in women's team pursuit. More...