Best route planning app for iPhone

[JQ]

I generally cycle close to home, so have never needed to use route planning apps, but next week I'm providing bicycle support for a charity event and will need to cycle from Coventry to Northampton on my own after the event, an area completely unknown to me. No doubt the car based sat nav apps I have currently on my phone will take me on major roads which I'm keen to avoid. What's the best cycling app to enable me to plan my route and use it as a Sat Nav whilst attached to my handlebars?

Cheers

Rich

[JQ]

Cheers for the help. Google Maps seems to provide a decent option, so will likely give it a go.