Alcal, Welcome to the forum. Trust me, you will never need a canopy if you choose the right tent for a bicycle tour. There are hundreds of tents out there that will stand up heavy rain. No tent will protect you against a very heavy storm or a tornado, but any decent tent will keep you dry under heavy rain. Plus canopies are way too heavy and bulky for a bike tour.
You may want to check this link, this is a guide containing several chapters with tips on how to choose a tent adapted to cycle toruing and advise on how to use and maintain a bike touring tent. There is even a part explaining how does the waterproof rating work. Enjoy!Guide for Choosing the Right Bike Touring Tent