This ride is over.

I think what I should do is take the Zumo XT, a Zumo 550, the Garmin InReach, and a phone running the app and another tracking app and compare distance results between all of them.

GPS tracked 167.5 miles. The App tracked 165.10 miles on the bike and 1.28 walking. 

1.4% discrepancy. 

Then after a stop and restart, it's now 155.34, so there is clearly a bug. 

Bad Object Decode Error - {'type':'member','context':'inline','guid':'137'} - - Syntax error, malformed JSON is home safe.

This ride is now underway.

GPS 82.7 All 81.4

Gas stop 172.2 miles 3.881 gallons = 44.37 mpg

Bad Object Decode Error - {'type':'member','context':'inline','guid':'143'} - - Syntax error, malformed JSON is going on Bad Object Decode Error - {'type':'object','context':'inline','guid':'39838'} - - Syntax error, malformed JSON.

Bad Object Decode Error - {'type':'member','context':'inline','guid':'137'} - - Syntax error, malformed JSON is going on Bad Object Decode Error - {'type':'object','context':'inline','guid':'39847'} - - Syntax error, malformed JSON.