Thanks. It's looking better. I just discovered that GermanWings will take bicycles as sports equipment in the hold. They only require a bike bag, not a bike box. They also do Rail & Fly bookings and the DB transport bikes too. I may be able to get to some of the routes I have earmarked in one of the three books I bought, The Best River Bicycle Routes in Germany, The 50 Best Long Distance Routes in Germany and The Best Bicycle Routes on Disused Railway Lines.
I like the look of the 300km Mosel river route from Trier to Koblenz and, although it is downhill all the way, I shall have to get fitter!