I suppose Google Maps has its uses but in my experience it can stumble badly when it comes to the bicycle option, I'd guess the data base that drives it in insufficient when it comes to specific local conditions.
Plot a route across my city and half the time it will route you down major highway access roads and such with no roadside clearance for bicycles. Otherwise on cross-country routes it will send you out of your way to official "bicycle trail" routes which may or may not be worth it.
The clincher for me was day three and 170 miles into my TX-NY trip where it routed me down an eight mile backroad that first turned from pavement to gravel, and finally to three miles of unrideable loose sand. A passing thunderstorm right before that didn't help it any....
...neither did the Texas sun in June and the complete lack of shade.
...nor the slip on sandals I was wearing, or the hills.
...and guess what a 33 pound bike with forty pounds of gear and water on it weighs.
IIRC that three miles took me two hours
And even before that stretch, the road names listed on google maps for the turns I needed often did not match what the signs read at those intersections. Especially true on backroads where what appears to be the same road on a map can be called on the ground by different names for different sections.
Anyhow, after that sand experience I mostly used Google Maps to calculate mileage after the fact, dragging the route on the screen to the one I had followed.
I will say though that paper maps en route are getting durned hard to find in this age when everybody navigates by iphone.
Mike