A bicyclist who collapsed in San Geronimo Valley after developing a heart condition on Sunday was helped by an anonymous person who performed CPR, according to the Marin County Sheriff’s Office. Lt. Doug Pittman said the man, whose name was not released, was in improved condition and being treated in the intensive care unit at Marin General Hospital this week. Officials said the 53-year-old Sacramento-area man was traveling with his 14-year-old son, who bicycled ahead…