We all know there are tons of iPhone apps that will track your bike ride using the GPS sensor and plot it out on the map. But what if you want to map out a route first, and then have the app tell you when to turn at various streets, etc?

I use RideWithGPS all the time to map out various routes, but they don't have a smartphone app, surprisingly. iPhone 5 with iOS 6 Maps does turn-by-turn navigation, but it's pretty much impossible to plot out your own route on there. Is there anything that will do it?