Congrats for the app! Great stuff! I was trying to find someone to develop a similar app but it would cost much more than 20 bucks ;)
To prevent the odo counting when stopped can't you simply didn't count any move below 2 mph? 95% of the false moves are below this speed even with very low signal. And... I think no one will run below 2 mph at more than 10 meter each rally stage.
Cap is displaying accurate values when stopped? I would prefer to disconect Iphone compass output and have only gps heading values, again not displaying any value given by a movement lets say below 3 or 4 mph. This way rider knows that the value displayed is the last heading he did moving.
Again, congrats, very good job!