I do exactly what Sachelis said. That seems the best to get to know roads before start. If you are in U.S. than Google maps offer you cycling routes also. Just pick it in the menu. For Europe I can't find that, so if anyone knows something about that, let me know.

P.S. I will open a thread with my routes (ridewithGPS.com) in Italy and France. It'll go from Trieste to Turin and from Lyon to Santiago de Compostela (Spain). So you can see there what we are talking about. Also, if someone knows better way that my or something to be seen in the neighbourhood, I'll correct it.