Well, I didnt do that particular route in such a way but the whole region. Five amazing days of biking non stop til the end of daylight. It was August and little traffic was found in the way, any. I stayed in Muggenbrunn and most of the roads from there southbound were enjoyed. Buy a Regional Map and get lost!!! I repeated a couple of roads just to re-enjoy them again, theyre that good. Also easy to find b&b at a reasonable price, same apply to restaurants... all good quality. And some tourism to do too if you like green, forest, and the lot. Not specially indicated if you like monuments or similars. Ill get there again, sure. Watch out some cows in the middle of the road though.
A real surprise, quite narrow but very twisty and enjoyable. There wasnt much traffic when we did it. Visibility is not great due to the trees, but its an excellent cross country route.
Leave Mullheim heading east and head towards Belchen and on towards Bernau and Sankt Blasien. The route rises and twist to about 1414 metres. Well worth a look