When I graduate from university in a little over a month, I won't have the audacity to ask my parents for
anything as a graduation gift!! My parents have been more than generous throughout my university education, helping me out with some of my basic needs.
Instead of expecting your parents to pay for a trip, why not work a few months, earn the money, save the money, and go on your own. You don't need an organized trip to see France. France is a great place to visit without someone escorting you. France is very easy to get around, the people are incredibly friendly and helpful, and there is lots to see.
Check out the Touring Forum for further cycletouring suggestions:
http://www.bikeforums.net/forumdisplay.php?f=47