We will be in the Loire in June for a week, staying in Vallieres-les-grandes (outside Amboise) and are hoping to do some biking. I have checked the loire a velo site and also the amboise TI site because we would like to do some biking around to the Chateaux. At first, I thought we would get bikes delivered to our accomodations for a week, but then, I am not sure if that is worth the expense. We have an 11 and 13 year old and have determined that about 15 miles per day is our limit. I have searched far and wide on the internet for people who have done the Bike thing themsleves in the Loire, but all roads seem to lead to guided tours. We booked a week at one place because we do best with a "home base" and touring out from there. We will also have a car, but any input or experiences with biking in the Loire are greatly appreciated. I do have the RS "Loire snapshot" book.
I'd check Detours de Loire, which is a bike rental company with many offices and drop-off points. You could bike one-way to a chateau and then take the train or shuttle bus back to Amboise. Or you can rent bikes by the day or week.