How long does it take to get to Beijing Stone Flower Cave if I take the 917 bus?

Tianqiao bus station is in the street opposite Nature Museum at the west gate of the Temple of Heaven. I doubt if there is direct 917 bus to the Stone Flower Gate right now. The bus has changed to No. 832. You should take that bus to Liangxiang Beiguan (良乡北关), then change to bus 833 to Shihuadong Lukou Station. Then perhaps take a locali minis bus about 5-10 minutes to the entrance of the sight. As I know, there are shuttle bus at Pingguoyuan Subway Station of Line 1 to your destination directly, at 9am.