Ultimate Rides is a fully offline, motorcycle optimised route planner for iPhone. When planning a route, secondary roads are preferred when outside of cities. When you are in a city, the route planner switches to preferring highways and trunk roads. This way you get the twisty roads when it makes sense to follow them, and artery roads when it doesn't.
GPX trails recommended by other riders can be imported and cropped. Combining this with the route planner allows you full control in creating your route, helping you to create your ultimate ride.