Garmin Edge and Zwift data difference

Hello all
Please help me!
I have Garmin Edge 830, Tacx Flux 2 and Zwift account.
I connected Tacx trainer as sensors to my Edge 830 and to Zwift.
While Zwift training I see different speed and distance on my Edge screen and Zwift screen.
I understand, that Garmin can’t see Zwift elevates, but it’s same sensor!
Which one is correct?
Please help

Hello @Yuri_Kaganovich, here is the explanation:

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Thank you!
So, which one is correct? :slight_smile:
Edge 830, or Zwift?

Technically they both are. Zwift is a fake virtual world, nothing in Zwift is “correct”, it is all your imagination. The Garmin is telling you how fast your wheel speed is, this is a real metric that is also “correct”.

Mind blown yet?

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Yes Mike :slight_smile:
It’s crazy… 40 km ride - 10 km difference… 20%

Easily explained however, Garmin doesn’t know what Zwift is doing in the virtual world so they will never match.


I think, that the Garmin data for speed and distance are more realistic

Yes, Zwift tends to be a little faster. No wind, no coasting, no stopping, etc.

Ride tempus fugit and you should be pretty close to them matching, but they never will be perfect.

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imagine putting your car on rollers and keeping to the same revs in the same gear and the car would say it had travelled X miles.

if you were to drive your car in real life and managed to keep the revs the same in the same gear you wouldn’t expect the distance to be the same. you’d slow down up hills, speed up down hills and slow down round corners etc

the “effort” the car did is the same in both scenarios but the number of times the wheels turned (i.e. the distance) would be very different and so the average speed would also be very different


Hi Mike,
my height, weight and heart rate are correct, watts should be too. :slightly_smiling_face:
Although, come to think of it, they could be a bit low :grinning:

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Of course, I was being facetious

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Wouldn’t this be explained by freewheeling in Zwift? If you’re going down hill, and freewheel, your physical wheel will slow down but Zwift will think you’re going considerably faster and therefore further.