Originally Posted by
adamrice
One Achilles' heel for all bike-computer apps is altitude. From what I understand, Garmin's own devices don't do a great job on altitude, and use desktop software to apply after-the-fact corrections. I know of one iPhone app, GPSies, that does after-the-fact altitude correction via the GPSies website; I'm not clear on this, but I think there are a couple others that will do on-the-fly correction internally by referencing online sources.
GPS is inherently poor for altitude determination (It's designed to locate a spot on a idealized two-dimensional surface). GPS devices that do altitude "well" use a barometer.
Last edited by njkayaker; 01-18-10 at 02:52 PM.