By Martyn Herman LEEDS England (Reuters) - Sprint king Mark Cavendish has warned that nothing is guaranteed in cycling after being installed as hot favorite to claim the yellow jersey after the opening stage of the Tour de France in Harrogate on Saturday. The 29-year-old, third on the all-time list for stage wins in the Tour de France, has never worn the leader's jersey despite enjoying 25 victories that have helped make him a household name. "There are always things that go right and wrong in the Tour de France - success is not a given," he told reporters. Everyone would like to win the yellow jersey. More...