Originally Posted by
Dr. Banzai
iMapMyRide is GPS based and is accurate over 40kms to 100m compared to my VDO computer which I measured the tire precisely. I use my bike computer to see my speed at a glance. If I want to see where I went I use iMapMyRide.
Smartphone GPS works just fine.
Forerunner==GPS. It's an Edge device in watch form (or, more accurately, the Edge series are improved bike specific versions of the original Forerunner units)