ZwiftHub vs Quarq DZero!

PLEASE HELP, this ■■■■ is driving me crazy…… :man_facepalming:

I’m seeing a 12% difference between the ZwiftHub power reading, and my Quarq DZero reading. This seems excessively large, and makes it tricky to switch from riding indoor, to riding outdoor, when following a training programme where zone accuracy is important.

I’ve done a ‘Spindown Calibration’ of the ZwiftHub (after minimum 10 mins warm-up, and not in erg mode), and also a ‘Zero Offset / Calibration’ of the Quarq DZero. (Offset was 664, and is consistently only +/- 10 points each time). I’ve also updated the firmware in the Quarq and rebooted it. I still get 12% difference in the power reading when riding.

The method I’m using when seeing this difference is by riding on Zwift with ZwiftHub connected (through AppleTV) as power-meter source. Simultaneously, I have my Quarq connected to my Wahoo Elemnt Bolt bike computer. When pushing 200w on Zwift, I see 224w (approx) on my Elemnt Bolt.

What am I missing here? Am I doing something wrong?

Without a 3rd reference point like power pedals, it’s almost impossible to know which one is more accurate.

Ok. Yeah, that’s what I was thinking.

I kinda think the ZwiftHub is the “cheaper” (read: lower quality) piece of tech. But the Quarq DZero is 7 years old, so it is older tech.

Should I just believe the Quarq because it’s better for my ego? :rofl::crazy_face::sweat_smile::man_facepalming:

If you dual-record and feed the data to the DCR analyzer that might give you some insight into how bad it is and whether it gets better or worse under different circumstances such as power level, flywheel speed (at different cadences), over time as the trainer warms up, or at different levels of battery charge in the crank based power meter. There have been some reports that the Hub power reporting changes as it heats up. You could also use the crank power meter as your paired power source in Zwift so it’s at least consistent between your indoor and outdoor rides.

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Thanks. I will try this.

I have a Quarq and it reads 3-10% higher than my Saris H3…Note that I seldom calibrate/spindown the H3 but do the Quarq prior to each ride. When I have spundown it makes no difference. I should start tracking the offset & slope of the Quarq that are generated.

The Quarq is never consistent in its level above the Saris…When within a few percentage points high, I have tried not calibrating and it just goes off even further.

I know the Quarq is high as i have P1s (powertap) and they were usually within 3% and consistent. I took them off to re-grease one of the spindles and have not gotten around to it.

the Quarq massages my ego so I live with it…I am not winning any races. When I do, likely when I am the only one in the race, I will figure out a remedy.

Thanks for the feedback. This is good info to know. :pray: