To plan the trip, I used:

the website Loire à Vélo  (see: http://www.loireavelo.fr/), which has detailed information on the cycle trails along the river,

Loire à vélo

Google Maps and Google Street-view,

John Higginson’s little guide, Cycling the River Loire published by Cicerone (Milnthorpe 2003), even though the author is somewhat opposed to the cycle trails,

 

the Topo France maps for the Garmin GPS devices (essentially the IGN 1:25000 maps of France) – absolutely essential for finding one’s way down the little lanes which provide some of he pleasantest cycling imaginable,

 

Garmin Topo France Cartes et accessoires navigateur route planner vélo

 

and sundry websites advertising the various chambres d’hôte at which I stayed,
e.g
http://www.chambresdhotes.org/ ;  
http://www.likhom.com/ ; 
http://www.oudormir.com/ ; 
http://www.charme-traditions.com/ ; 
http://www.clevacances.com/FR/.

But there are others.