Bobby Valentine announced over the weekend that he’ll ride the Pan-Mass Challenge this year. He spent some of his Fenway Park time on Saturday hanging out with friends of Pan-Mass, including Tiffany Ortiz, Stacey Lucchino, and 12-year-old Tim Burke of South Boston, who is being treated for leukemia at the Jimmy Fund Clinic. Valentine has chosen a one-day Pan-Mass route from Wellesley to Bourne that will get him back to the team as quickly as possible. The Pan-Mass Challenge, which benefits the Jimmy Fund, is Aug. 4 and 5.