Not perfect but impressive none the less – Ride with GPS: Bike Navigation Review

Works well to provide turn by turn route navigation for your bike rides (with audio!). Just go to the RWGPS website to sign up for a monthly or yearly subscription. I can connect my iPhone to Bluetooth 4.0 bike sensors and a Wahoo RFLKT. The data fields on the RFLKT are the same as in the app. To select a different category to display, touch and hold the data field in the app. One small problem is that the GPS tracking has a snap to road tendency that is a bit too aggressive but if you stick to riding roads and not smaller bike trails then it won't be a problem.
Review by OneDaoist on Ride with GPS: Bike Navigation.