Beathard will start Thursday's preseason game against the Chargers, Tom Pelissero of NFL.com reports.
Jimmy Garoppolo will wear street clothes during the exhibition finale. Beathard is the clear-cut No. 2 QB in San Francisco, and he'll mostly play against and with depth players Thursday. The 23-year-old is still a project for the Niners after he played seven games last year, completing 55 percent of his passes for 1,430 yards, four touchdowns and six interceptions.