There are lots of local cycle routes which are generally well signposted. If you go to any of the local Tourist Information Offices they will be able to provide maps and advice. I'm sure an internet search will provide information on tour companies but can't comment on any of them as I prefer to make my own tours up as I go along.
Amboise is a very nice town to use as a base, plenty of nice shops and cafes and some really nice cycle routes. The Chateau Chambord is spectacular and, again, lots of really nice local cycle routes.