Speed/distance inaccurate

I’m trying Zwift free right now and am trying to work through major issues with inaccurate speed and distance within Zwift. I’m using a dumb trainer with a wheel sensor (i’ve tried two a Wahoo Blue SC and a Wahoo Speed) and the data inside Zwift is WAY off. Like 1/2 to 1/3 compared to Garmin. Is there anything I can do to resolve this MAJOR issue.

Hi @John_Galea

Welcome to the forum.

See if this help.
How Does Zwift Determine My Speed?


So if I understand right, there is no solution to this issue of 1/2 to 1/3 actual wheel speed?

You can’t compare your actual wheel speed with the speed that Zwift calculates. It’ll very rarely be the same, if ever.

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Sadly this makes zwift useless for my use case but thanks for letting me know so I stop wasting time finding a solution.

It actually makes the Garmin useless. The Garmin doesn’t know if you go up or down or if you are in the draft or not.


Hi @John_Galea, you need to wrap your head around the fact that within the virtual world of Zwift there are many factors that effect your speed, it is not just how fast your actual wheel is traveling. You will see how this works in the post that Gerrie pointed you to.

Also, make sure you are selecting the correct wheel on trainer from the pairing screen, do you have one that is listed or are you choosing the “unlisted” trainer? That can also be an issue, if Zwift doesn’t support your trainer then they are guessing what power curve to use and it could be way off.


What are the details of your use case?

Because I am using a dumb trainer with no feedback to Zwift other than wheel sensor and heart rate monitor the concepts of wind, drafting, hills and the like are in no way relevant. What I was hoping for was a simple animation, a sort of augmented reality, that takes in account what I’m doing on the bike.

So if you had a smart trainer that changes resistance automatically, then you would like Zwift?

You can change gears to simulate the incline and decline in the game.

In real life there are factors that alter your speed. Road resistance, wind, hills, drafting, weight of equipment, etc. Why should it be different in the game?

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