I don't quite understand why this device solves the fundamental problem, which is the fact that the hard drive is spinning up after 20 minutes, and, if you are bouncing too much at the time, the unit can crash or simply take a lot more time to read the data. I can tell you this from a LOT of experience running for MANY hours with an iPod (I'm an ultrarunner and often run 3-6 hours at a time): On my desk, an iPod will play for 8 hours (I have the original 5 GB unit). When I run with it, it gets 2.5 hours TOPS, 2 hours much more typical. I take this to mean that it uses up much more power because when it is reading the disk it gets misreads and has to therefore spend more time and more power rereading the disk. If anyone has a better explanation, I'd love to hear it. My DATA is reliable, but my explanation is just a guess. I run with the iPod in an old Handspring visor neoprene case, which works just fine.
Three Pieces of Good News from Cupertino
Review: iSport, Run With Your iPod