I use Runtastic "Road Bike Pro". It does what I need it to do. Actually, it does a lot more than I need it to do. When I compare the mileage from ANY GPS app that I've tried ( I've tried 4 so far) to my Cat Eye computer it comes out to be about 7-10% less than the computer reads. I just figured that since the GPS is performing a running string of point to point measurements which are straight lines. Some corners and turns are shaved a bit. Whereas my Cat Eye represents a direct linear record.