Bett & Bike is a German cycling association which lists 4.000 ADFC certified bicycle-friendly guest houses in Germany.
Bett & Bike translates to
Bed and Bike and each guest house fulfills more than the minimum requirements prescribed by the ADFC to cater for touring cyclists.
Whether they are a comfortable hotel or a cosy pension, they all welcome cyclists who only wish to stay for one night, offer secure accommodation for their cycles and also provide facilities for repairs. Provision is made for drying wet clothes and equipment and there is access to maps and timetables.
Finally, guests can expect to receive a hearty cyclist's breakfast (Radlerfruehstueck).
You can find listings, maps and links on the Bett & Bike site, allowing you to construct an independent tour.