Head Unit Power Drastically Different Than Zwift

So I finally pulled the trigger on some pedal based power meters. I picked up the Assioma Duo’s and a Garmin head unit (Edge 820). I’m riding a Kinetic Smart trainer.

What I’ve noticed is that the readings displayed in Zwift are DRASTICALLY different from the numbers displayed on my head unit. For example, when doing the Tour of London, my head unit was displaying power 155 and Zwift was only showing around 65! Essentially, the power displayed in Zwift is anywhere from 50-75% off! That obviously can’t be right…

Is there something special I need to do to get these numbers to jive? I can’t believe they would be that far off from each other. I’ve done a calibration through the Kinetic app, but still seeing the major difference between power readings.

Thank you

When pairing your devices to zwift you can choose to use your Duos as the power input and the kinetic as the controllable trainer.

Yes…I know. That’s what I did. And the power displaying on the head unit is - as I mentioned - drastically different than what is displayed in Zwift.

Are you using Bluetooth or ANT+ , it sound like your pedals is only sending one side.

I’m using Ant+…

If they were only sending on side, then wouldn’t the head unit also reflect just one side being communicated to it?

No, you could have one connected to Zwift and both connected to your head unit. ANT+ would allow this.

The two pedals don’t broadcast independently of each other. The right pedal “pairs” with the left pedal and sends its data to the left pedal. The left pedal then connects to head unit, etc. and broadcasts all the data via Ant+.

That’s why when you connect, you ONLY see the Ant ID of the left pedal, even though both are “transmitting”.

Refer the following article:


Thanks, Nigel.

But does that article also apply to Ant+ with the Assiomas?

ANT+ should work. I’ve used mine on Zwift once without any issues.

I did a calibration through the Kinetic app, zero calibrated the pedals via the Assioma app, and made sure to use the Ant+ connection to Zwift.

So now, I’m not seeing the exaggerated readings I was seeing before, but I am seeing some occasional spikes in both directions. Sometimes it will suddenly drop to zero, then level out, then suddenly sometimes spike way above what the actual power is and then level out.


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