great biking around the town of Freiberg in the south wet near the borders of France/Switzerland. as in really great biking! it appears that over half the population ride… bikes everywhere.
again the area near Titisee (lit. Lake Tit) is nice and as some good riding. a friend works (or at least did last time i heard from him) at the bike hire centre there.
but Bavaria is better for riding, walking, beer and there are loads of lakes that sit at the foot of the alps…. look up Walchensee, Tegernsee, Cheimsee and Neuschwanstein Castle (there is a nice campingplatz on the lake there). is is another 3,5 hours further than the Balck Forest, although that may not make any difference to you if you are coming from the north.