Speed issues

(Dave Redmond KISS(C)) #1

I am currently running the following set up:

Tacx Vortex Smart

Garmin 510

Garmin Ant+ dongle


The problem is that I have is speed on my garmin 510. Does not match with on my computer screen there is a 10 to 15 km difference. Is it possible that computer is running is in miles an hour and my garmin 510 it is in kilometres

Please help Dave

(Noel Nunkovich *USMES*) #2

This is standard practice for Zwift. Your speed “in game” is calculated by the game engine based upon your weight, your current power, and the internal physics engine of the software (comprised of things like current grade of the virtual road, virtual air pressure, etc). Your speed on your Garmin is purely a factor of rear wheel revolutions and is controlled primarily by gear selection. Your speed in Zwift has absolutely no connection to your rear wheel speed on your trainer. If the two ever match it’s a complete coincidence. Don’t worry about it, use the speed on the Zwift screen and ignore your Garmin.