Does Your Power Meter Work With ERG?

My setup: Wahoo Kickr V4, ATV 4K, 4iiii crank based power meter, ZCA (all on the latest firmware / version).

The issue: ERG won’t engage when the power meter is paired as power source but will engage when trainer is selected. Obviously in both instances controllable is set to the trainer. Sim mode is fine with either PM or trainer selected as power. Tried connecting through ZCA & direct to ATV (without HR so not to go over the BT limit on ATV) with the same result.

I’ve raised a support ticket & the upshot is they say it’s not recommended to use the PM as power source in ERG “because of major inconsistencies in programming for various BLE signals from a myriad of different devices”. Additionally “power matching is quite unreliable as to when it will work on your trainer, but not on someone else’s even if it’s the same model. We aren’t even saying that because it doesn’t work now it might not work the next time”. The upshot is it might work, it might not & basically that’s the way it is & it’s not being looked at as a “bug”.

They also suggested I should come on here & see if anyone else has this issue & what (if any) workarounds there are.

The obvious one is to use the trainer as power source instead of PM but to me that’s not the answer. I’m no expert but I honestly don’t understand why it doesn’t work & their response as to why is just poor TBH.

Anyone else use their PM as power source in ERG? If so does it work all the time & what is your setup? Obviously particularly keen to hear from anyone with a setup similar to mine.

I think Trainerroad can do what you want to work as they have a feature called power match - Im not sure if something similar has ever been present in Zwift as I have always just run with the trainer in erg mode.

Not much help there… Sorry :slight_smile:

One of the replies support sent to me mentioned Zwift has power match but clearly doesn’t work in the same way as TR.

why buy a £1000 trainer only to not use the power meter on it???

I use the bike outside as well so the Kickr power meter isn’t much use there.

Both my wife and i use a Stages crank based power meter for power readings and Tacx Flux for resistance. We regularly use ERG mode and have no issues, however we do connect over ANT+ protocol in to a Windows machine.

If you use the 4iiii for power readings in SIM mode and there is no issue then i see no reason why this would not work in ERG mode. The power meter is essentially doing the same job, simply advising Zwift of it’s output. Zwift then tells the trainer to ease/ increase resistance.

Have you asked a question of Zwift support?

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I don’t see why not either but for whatever reason it doesn’t work. Maybe it’s because I’m using ATV rather than a Windows OS? I don’t know.

I’ve quoted some of the Zwift support replies in the OP but essentially they are saying that they can’t be responsible for making every BLE smart trainer & power meter on the market compatible with the platform.

Summary - It might work, it might not.

It may work 1 day, it may not the next.

It is what it is.

Tough basically.

Their last answer was actually to ask on here hence the post.

Not happy at all with their repsonse. This is something that should be worked on for future releases to ensure major power meter brands such as 4iiii, Stages, Shimano etc are compatible with the platform no matter what the brand of trainer is.

Poor from Zwift IMO.

do you pair the trainer in the controllable section when you pair your power meter for power?

I use my pedals for power and it works fine for erg mode, the reason I do is that my trainers power reading is terrible (elite zumo or tacx flow both are equally bad!)

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Yeah trainer is paired as controllable, PM as power / cadence & HR monitor = ERG not working.

As soon as the trainer is selected for power it works.

I’m thinking it must be something to do with iOS & it isn’t getting fixed anytime soon (or at all) judging by Zwift support responses.

I have never used ATV before but can’t you only pair 2 different bluetooth devices?
so if you have trainer, heart rate and power meter that would be doable would it? maybe one isn’t paired correctly?

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Ordinarily yes, you can only pair 2 devices but you can pair them all through ZCA as this combines them all to 1 BT slot.

I’ve tried both that way & pairing direct to ATV (omitting HR strap so as not to exceed the number of slots available) but PM doesn’t work ERG either way.

Zwift acknowledge it is a practice that’s “not recommended” so they are clearly aware of the issue the just seem unwilling / unable to rectify it.

That was going to be my next suggestion.

The Kickr is generally regarded as having pretty accurate power, have you compared it to the power readings from your power meter? could you use the Kickrs power for zwift if they are similar? or make adjustments if it reads higher or lower when you use erg mode?

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TBH I haven’t no. I’ve only just run into this as I’ve only had the PM a few days. I just (wrongly) presumed I could use it both inside & outside.

Obviously it’s not a dealbreaker as I can use the trainer for ERG so all is not lost but my real frustration is that the responses I’ve had from Zwift are unhelpful at best, completely disinterested at worst.

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yeah, i can see how that would be frustrating.

If you have a bike computer connect your power meter to that and see if the power readings match what zwift is saying. If they aren’t then maybe adjust the watts for the erg mode accordingly.

Not ideal.

Either that or just buy a cheap windows PC! haha

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A work around would be to do some testing by dual logging a ride on zwift and bike Garmin/ Wahoo etc. Pair your trainer to zwift and your PM to the computer.

It’s probably not as simple as working out a percentage difference but you could do that and then adjust the workout difficulty accordingly when using ERG.

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That was basically what I was saying

Yeah I think that’s what I’m gonna have to do.

I can’t believe I’m the only one to run into this problem though.

I don’t think they really care that much about the training part of Zwift. All other training platforms can easily deal with this combination.

I use a similar combo, but not in erg mode on Zwift. I use erg on TR (often with Zwift as an output, using the power meter as power source in Zwift), or I ride in Zwift (again using the power meter as power source, trainer controllable).

Because you want a single source of power for indoors and outdoors. Because there are a lot of other trainer features you are still using. Because even in powermatch, the trainer still uses its internal power meter.

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Zwift on PC, Tacx Neo.
Tested Neo controllable + P2M NgEco for power + cadence, no problems (Erg & Sim modes).

Power Neo is spot on with P2M (± 2%).

Edit - Zwift support has no idea what they say.
Why should it be a problem for the software? Zwift is just receiving the data transmitted by powermeter - and which one, BLE or ANT+, does not matter. It is the same “problem” as “red colored frame can be responsible for issues”.

By the way - I tested both BLE ana ANT+, double recording with free Jepster app (on the mobile phone running ZCA) - no issues.

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Thanks for all the replies. Much more helpful than Zwift support who I was really disappointed with for the 1st time I have to say. Every other time I’ve dealt with them they’ve been fine but not on this occasion it seems.

Did another ride yesterday & had a play around with it but still won’t work. ERG mode will just not engage with PM as power source no matter what I do.

Frustrating but it is what it is I guess. I can still do workouts but as the above poster said I really wanted the same source of power indoors & outdoors.

Looks like it’s not to be.