Speed higher than sensor data


(Yves Ferland (mtl)) #1

Hi all,

I just performed my first test with Zwift… Wow, I like this platform, will definitively subscribe once live in production.

I’ve been ridding for a long time with Trainerroad and I noticed that TR gets power and cadence data from my Stages power meter. Whereas speed data is feed from my regular Garmin speed sensor on my rear wheel.

On Zwift however, I noticed that there is no way to capture speed data from the Garmin sensor. Once I select my power meter, I get both power and cadence from my Stage PM which is perfect, but speed seems to be ‘calculated’ by Zwift from the power data…? Am I getting this right?

So, during my first test drive with Zwift I noticed that my power and cadence were 100% acurate with source data, but speed was significantly faster than I was really ridding. For exemple, on the begining of the Richmond route, no hills, my real 28 km/h ridding was displaying 34 36ish km/h… like if I had a tail wind helping me…

Is this normal? Like, Zwift simmulates tail and front winds or is it just the speed calculation being a bit generous…?

Thanks in advance and keep up the amazing job - this platform rocks !

Yves


(Yves Ferland (mtl)) #2

Hi all, sorry for my ignorance ! I just read some posts here explaining Zwift derives speed from power data and also calculates winds etc for real-life experience. I’m impressed. Please ignore my question on speed :slight_smile:


(Mark Hewitt) #3

You got it. The *only* input which Zwift is taking into consideration is the numbers from your power meter. The cadence is just to show on the graphics and the heart rate is just for your own reference. 

It then takes the power numbers and transposes it onto the virtual environment to generate a speed.