Scenic S0, flows on a steep road (S1?) To the Partnach.
However, it was extremely frequented by pedestrians (on a holiday Monday around noon). It was like that until Partenkirchen, whole busloads full.
The route between Elmau and Garmisch can easily be traveled on a mountain bike. Very scenic and varied. Only the descent from Graseck to Partnach is violent and not entirely safe. Do only with top brakes!