Euro cycle routes are supposed to chart simple, safe long distance routes for cyclotourists. This principle has escaped those that organise bike routes in the département of Maine et Loire.
The Loire à Vélo makes up the French end of European route 6, which goes from the Black Sea to the Atlantic. The Maine et Loire covers a significant section of the route extending from Saumur to St Florent le Vieil.
Their priority is not simplicity and comfort for the cyclist, rather it is to ensure he goes past as many tourist sites as possible. They think nothing of signposting a route that entails a 12% climb to go past some influential winegrower's vineyard. It escapes them that someone on a fully loaded touring bike is unlikely to be in the mood to appreciate it after the climb.
I strongly advise anyone thinking of cycling in that area to check on this, or similar sites, what the route proposed entails - to avoid bad surprises. An example : Saumur to Montsoreau - they propose going via the vineyards of Saumur Champigny (very good wine, no question). From Saumur you will find yourself on a section of 1 in 10 to get up to this paradis viticole. On the other hand, the D road out of Saumur to Montsoreau is flat, well maintained, and with very little traffic on it, and you can trundle along without any worry or wasted effort.