Not sure if this is an issue or not, but . . .
Since riding counterclockwise, I have found that the distance measured by Zwift is consistently and significantly shorter than distance measured by my Garmin. Did not have this problem when the direction was clockwise around the island.
Here are my constants:
dumb trainer (Kinetic Rock & Roll)
Quarq GXP power meter (it’s old, but has been reliable)
Generic HR strap paired with Garmin
Speed/cadence sensor (can’t recall the model)
When riding clockwise, I would find that distance in-game was periodically off from distance on Garmin, but it seemed plausible that this was due to the changing grade of the terrain in-game, while my trainer remained constantly flat. This was confirmed by watching the distance measures both in-game and on the Garmin. I’d find that during uphills, I’d slow down in game and get ahead in distance on the Garmin, but catch up on the downhills and flats. Results were that final distances were always pretty close – usually within .1 or .2 miles of each other.
When riding counterclockwise, the same phenomenon occurred (unsurprisingly); however, I was never able to “catch up” in-game. On a 7-lap ride, I would continue to slowly lose ground between in-game distance and distance measured on my Garmin. An hour-long ride usually ended with the Garmin showing between .6 and .9 more miles ridden than the game.
Wondering if this is a glitch in how speed is calculated in-game, or is it somehow due to the longer hill going counterclockwise? It seems to me that regardless of the hill, the distances should still even out in the end. Minor issue, but I’ve noticed it consistently since the switch to counterclockwise.