Wonderful detour from B42 between Königswinter and Linz. L331 up from Königswinter to Margaretenhöhe is smooth like a race track with several very intersting curves. If there are no cars slowing the progress, it is good fun to go up and down a few times. L253 winds down through the forest into Linz town.
In Linz, have ice cream at Ciao Ciao Gelato, next to the ferry terminal.
Königswinter is where you can show off your bike on the promenade and have your Apfelkuchen at one of the many riverfront cafes on Rheinallee.
Beautiful road along the Sieg River. Nice curves and mostly smooth surface. Rast at Bikers Rast Dattenfeld or Burg Blankenberg. At the Eastern end, you can connect to B256 Northwards and loop back West on B478.
Beautiful scenery - B256 through the forest, B478 along the river between farms. Curvy road with good to excellent surface.
Wide and winding along the Mosel river
Beautiful scenery and sweeping curves along the Sava river. Great visibility most of the time. Road surface generally good. Ride around Lake Bled, go for a swim in Lake Bohinj or the river, take the Vogel cable car up to 1540 meter.
This really twists and turns alongside the river Wied and is great. The map is not very clear but take the L255 north from Neuwied towards the No. 3 Autobahn and under that to Neustadt. Enjoy.