Dual recording power and Transparency

Dual recording power

Sadly Zwift power decided to remove uploading dual recorded power files for analysis due to technical/stability issues (as far as I understand).

I want to clarify that I’m not trying to put pressure on the people of ZP.
I’m thankful for their work, still a happy user and respect them very very much!

Could we get dual recording in Zwift? Let Zwift record 1 primary and 1 secondary power source. Have it let show a similarity score in %.

This way Transparant people like myself can show what we do is real. Not that I’m a pro or even in the A groups but still I like to back up my numbers with some proof of realness. (And I hate losing to people I know from IRL that couldn’t win even if they had their best day ever and I had my worst)

It could show double :zap::zap:︎ in green when between 100% - 97% (fine/acceptable)

in orange when between 97% - 95% (calibration needed/warning in races)

in red when below 95% (calibration needed/ DSQ in races?)

If already seen comments like:

“Only for the rich/pro’s”

But basically, it is the same as Zpower vs Real power.
There are people that ride non-smart trainers
There are people riding a Vortex/Rampa with power estimation that are very well known to overread.
Then there are people that ride the upper market trainers.
And we have people riding upper market trainers and having an on-bike power meter.

We could have:
Entry-level - Zpower
Moderate level - Real power
Advance level - Dual power

If Zwift would build my idea, ZP could maybe just show DP was recorded with a similarity score of X%.

Please build this!!!


agree with the above we have lost a very good step in the correct direction for transparency


It was a sad day when I heard that ZwiftPower.com had to discontinue this function. I really did enjoy it. It’s both a great validation of my true ability (or lack there of :joy:) at the moment and it was an even better way to keep racers honest.

One thing I will mention though is that you need to be careful with margin of errors. My Hammer has a ±2% and so does my spider based power meter. My spider power should be a fraction lower than someone’s power pedals but should always be higher than my trainer due to the drivetrain inefficiencies. If one has a race ready cleaned and waxed drive train they will achieve much better results on the trainer than someone that hasn’t cleaned their bike after a rainy ride, but should their power meter be in the cranks or pedals their power should remain the same since the measurement is closer to the output.


@Paul_Allen should this be switched to feature requests? Thanks!

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Placed in feature request!


At 300w 3% difference would be 291w lets say ons a 3 or 5 sec alg. these numbers would be pretty close.

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dont underestimate a 9 watt difference im using my P1 pedals for power (last race) they are approx 9 to 10 watts more than my neo; the race felt significantly easier and i had the energy to muster a decent sprint fine lines are the difference between a win or a loss

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This can’t be overstated enough I reckon. One source reading -2% held up against another reading +2%. They’re both perfectly legitimate measurements in themselves, but they create a 4% difference - and we’re still no closer to knowing which one is actually the more accurate.

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Reckon I should be able to pair up 2 or 3 power sources, and at any given moment Zwift should use whichever one is reporting the highest power. :smiley:

That’s without even starting to think about your new 10t cog, dirty chain, worn out bearings, etc.


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Just from the chain here are the quick losses that I could find estimates for:
12w clean chain
5w good chain
4w right length
3w cross chaining
2w chain tolerance
2w chain wear
1w deep clean
4-5w super lube

As always that is the responsibility of the rider I guess.

Yes, please.

If Zwift could support zwiftpower with more serverpower it could perhaps be switched on again?

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As seeing that in most races, I’m just trying to make it to the finish with the likes of Indoor Specialists, I’ll pick 300 watts over 291 watts EVERYTIME, if given the option. For me that would be 4.225 w/kg vs 4.099 w/kg, which looks to be just good enough to finish top 20 in most A races.

Personalty I think there is more to it than Server power. If you don’t have a secondary power meter you look like a cheat. That feel wrong.

Power meters all have aberration, so even on 1 source, you could have an over or under-read of ~0,5-3% depending on your meter. Dual power setup only shows that your primary source isn’t way off. Some wheel-on trainers have power est. instead of power meters, they are known for over-reading. My Elite Rampa ie did over-read by 15/20W. at 250W to my 4iiii power-meter, I now have a Direto II that is within ~3% of my 4iiii power meter.

I have seen people with a Vortex thinking they can hold 310W over 20min at a heart rate of 155bpm.
When in real life they struggle to ride (estimated by strava)150W at 150bpm.

I have ridden the same Zwift and IRL events as the person in this example.

What is suggesting is more for transparency, not for calling people cheats.
People who have a dual power setup could really benefit from the similarity score.
I love to know my numbers are real, this way there is less doubt.

That is not the the point Im trying to make.

Reasons for dual power for my are:

1.) Transparency in races to others (I Win/Lose transparant, not having Dual power isnt bad, having is just a plus)

2.1) Self control, are my numbers real? Self verification.

2.2) Calibrations alerts

Not having dual setup is just as looking like a cheat as riding with ZPower, no big deal.

First of all: Which protocol is the most accurate today or in other words which Powermeter unit is the most hightech? Cyclus2 or SRM i guess is still the line … and even here … I saw powermeters which show approx. 30 W lower over time because their strain gauge were less accurate (especially the case when heat or cold is involved - temperature drops/ups).
Pedals are different to crank spider measuring units. I’m pretty sure many Smarttrainers don’t show exact values by different temperature and higher wattage to each other. The point is: if you want it even more serious too much effort is involved to stabilize reliability.
Still the question of all question to this case is: Which is the most accurate powermeter?

I want a backup power source just so if one drops I don’t come to a standstill. Link my power meter and my trainer please - average then together if you want.