Q: Are there still TI centers in small german and austrian towns where local accomodation bookings can be arranged for stays of one night while biking along the Danube river?
A: Yes, tourist information centres in both Austria & Germany offer this service. Some charge a small fee but they are usually the best choice for finding you a last minute bed for the night.
Virtual Tour of Fish pond & flowers in Volksgarten,
Vienna,
Austria