I've also found another good ap called "asking directions" for those occasions when you know you are off-route.

I've used Google map directions for my last four summers' 1000 mile tours and will continue to do so, but they aren't everyone's cup of tea. I don't have a smart phone or a GPS.

I print out the directions like a cue sheet (16 pages worth for last summer: Duluth, MN to Kingston, ON) after studying and tweaking them on the screen. I annotate the printed version where I think I need some extra info, with distances set to read in kilometers and my odometer set accordingly. Then when it tells me to take a left in 300 m I can tell by my odometer when I've gone .3 km much more easily than 984 feet.

Each successive page goes inside the map pocket on my handlebar bag. I like to see the progression taking place, though a single page may represent anywhere from 259 km (the MI U.P.) vs. 17.5 km (getting from the bus stop in Duluth to the outskirts of Superior, WI and the start of the Osaugie Trail). For the shorter legs (<10 km) it's easy to match the Google distances to the odometer but there is a margin for error that makes that more difficult for the longer legs. Sometimes the directions will only tell you to "turn toward" a certain named road when that turn is an unnamed bike path (which was the case with the Long-Hastings section of the Trans Canada Trail). If you don't have a pretty close fix on where to make the turn you can miss it.

Hence the back-up strategy of asking someone local for directions. It usually leads to a nice conversation about where I started and where I'm heading and can even result in kind offers of help and a place to stay for the night. I highly recommend it.