Sorry for the late response, but I had to leave home early yesterday to join a ride; and I returned home exhausted and sweaty. Body and brain have now partly recovered, and so I'm ready to experiment. The phone got my .gpx file into the device, and the device shows that yes it has the .gpx file. I don't know how to display the .gpx file, but maybe that's because there's no signal where I am, indoors. And I'm indoors because (i) it's bucketing down outdoors and (ii) I'm a wimp. The bike's going in for servicing later today (and I shall get thoroughly wet), and I'll get it back on Monday. First priority: turning off the noisy beeping!

I wonder how long it will take me to remember the functions of all six of the buttons on this device. Oh well, this system perhaps beats that of a touchscreen non-operated by sweaty fingers and operated by raindrops.