Alternatively create a route in ridewithgps on PC (or upload your
cycle.travel gpx track into ridewithgps), download the ridewithgps app to your phone, find your route in the app and go "Ride this"*. Haven't tested this though.
*edit. to use route offline: go to route and press download (red arrow), get this:
OOI may test a ridewgps route nav on commute.
edit.edit. attempted to test at the w/e, alongside etrex, but gave it a miss after not working out what I was doing wrong.