Speed and distance discrepancies Xert/Garmin vs. Zwift

I’ve been doing my Xert workouts using my Garmin 530 and connecting with Zwift. It works well and helps keep things engaging. However, I get significant discrepancies in mileage and speed between Zwift and Garmin. Today I did Lucy in the Sky. According to Zwift, 36 miles on a pretty flat route. According to Garmin, 40 miles. Zwift uses your power to estimate speed given the terrain. What is different with Garmin?

What is the correct distance? If you ride on zwift you should be able to find it back from the course. It would help to pin point the potential issue

The way Garmin calculates your speed. It will be based on power only, as you are not actually moving, but depending on your setup, wheel rotations may be a factor too.

Zwift’s own ‘distance’ is determined by the course, but it will never be the same when compared to your Garmin, as there will be some change in terrain.

Export your Zwift ride, i.e. download to your PC and do not connect Zwift with Garmin, because then it won’t sync with Xert. Upload the file to Garmin and the distances will match AND it will upload to Xert, provided you already have that link established…

But, depending on the course, you will have a time zone problem. You will also have a duplicate, so you would need to remove the Xert app recording.

If you want the ‘correct’ Zwift distance to sync, try this next time. At the end of the day, it doesn’t really matter, at least not for Xert.