I have hotel reservations in Lindau for the first and last night of a planned bike trip around the Bodensee in late May. Do I need to make reservations for the 3 in-between nights, or will I be able to easily find a room each night? I have no idea how busy late May is in that area; I'm not sure exactly where I'll be each night, but could probably work that out if I have to. Would appreciate any thoughts/help in making my decision.

Probably not. It may get a little crowded between May 25 and 27, because it is a long weekend in Germany.
The best idea is if you ask your hotel receptionist in the morning before leaving for a recommendation for the next night. They also can help with a reservation.
Pre-booking on a bike trip can be hard, because you never know what happens, how far you will come, how the weather will be etc.

t1959 -- And that's exactly when I'll be there (23-27)-- is it Pfingsten (sp)?
Thanks for the good suggestion to ask the hotel receptionist.

It's Himmelfahrt (Ascension Day) and it will be crowded. I highly recommend to book in advance.

It's the one area of Germany that we had some difficulty finding a room without a reservation. We did find a room but we had to drive farther than we had planned.

Well, that settles it. I'll work at figuring out how far I'll bike each day and make reservations. Thanks all!

Well, I'm glad I asked, and I'm glad I made reservations. I made at least 10 phone calls before I got the rooms; 2 nights in Konstanz and one night in Immenstaad. Emails were not being answered, and many hotels are completely booked during that holiday week. Thank you all, especially Ingo.