I am using a Forerunner 920xt with a GSC 10 ANT+ speed and cadence sensor. I have been using the same devices for a few years with no trouble. On my ride two days ago I noticed the MPH would fluctuate greatly. On a stretch of road where I am usually at a constant 19 mph it would jump from that number to 37 mph, stay there for about 10 seconds or so and then go back to 19. It would do this over and over again for the entire ride. Today as soon as I started my ride it jumped up to 30+ mph and stayed there the entire time, never falling below 20 mph. My distance was also completely wrong-- the route is 25 miles exactly, and the total distance at the end of the ride was registered as over 50 miles.
Some other notes: I am not using glonass, my wheel size is set to manual (2121), and GPS signal is strong. None of the settings have recently changed. I am using an IQ app called "Pro Cycling" by RH-Sports. But again, I have been using this app for a while as well with no issues.
I plan to try changing the battery in the speed and cadence sensor, as well as trying a ride using the regular cycle selection on the 920xt instead of the IQ app. But are there any other known issues or tips people can relay that might help solve this issue?
Thanks!
