Originally Posted by diverguy

I've used both the iPhone (various cycle tracking apps) and a Garmin 800. I experienced all of the issues the others talked about -- low battery life (resolved by connecting an external battery), no heart rate or cadence monitor, etc -- however, there is one issue that hasn't been brought up yet. It may or may not be important to you; it was very important to me. The iPhone apps that display your GPS-tracked location on a map depend upon a data signal to render the map, otherwise you're just a got on a blank, gray grid. As I often do extended rides into unfamiliar areas that have no data signal (or any signal at all), the map would sometimes not render, leaving me effectively lost. It was for that reason that I switched to the Garmin with the internal maps.