Control smart trainer's resistance with external power meter - important for Workout Mode

(Bogdan Urma) #1


A few months back, I submitted this request:

Now that Zwift has a workout mode, it’s more important than ever IMHO to implement such a feature, much like Trainerroad’s PowerMatch. Otherwise power numbers won’t mean that much, as trainer’s power is always different from power meter power, which is also used outside. If “Workout Mode” is to be a serious player, IMHO this feature needs to be implemented. If Zwift is telling me to hold 250watts for 1 minute, and sending a signal to my smart trainer to hold 250watts, that may be + or - 10-20 watts on my SRM meter, as they never agree. So it’s important to have it match. For general riding around, it’s not needed, but for “Workout Mode”, it is.




(Eric C. (Zwift HQ)) #2

It’s on our radar.

(Jeremy Smithers) #3

I’d love to see this too. My Wahoo Kickr Snap seems way off compared to my power meter :frowning:

(Mark Minn HPP) #4

This seems very important for anyone using a smart trainer in workout mode now that Erg has been disabled when a power meter is the power source.

(Mark Hewitt) #5

This was working ok for me on Tuesday with a Stages PM and a Tacx Bushido, even if it did feel a little ‘loose’ compared to the same setup with Trainer Road.


But now it’s been removed, very strange.

(Karissa Minn) #6

In the meantime, could people with smart trainers and power meters please be allowed to select ERG mode if it works for them? Not everyone was having the issues that caused it to be disabled in the update. It could be “off” by default, and checking the box could pop up a warning if needed.

I don’t know if this should be a separate suggestion or not…

(Bogdan Urma) #7

ERG mode should be enabled all the time except for FTP tests. External power meter or not.

(Steve Sullivan- RO4H) #8

An easy way to accomplish this would be to have a constant offset setting ( like some other programs ). This way you could take readings from your PM and from your smart trainer and see how many watts they differ by. Then you would simply put that number into your offset data field and apply. Then your wattage reported from your smart trainer would match your numbers from your power meter.

(Bogdan Urma) #9

The problem is that in my experience, constant offset is not reality. Offset starts to drift. 

(Rune Olofsson.100kg69y) #10

There is just one solution when using power meter and a smart trainer.

Get the power from the accurate source (PM) and adjust the smart trainer to hold the training power within limits.

(A rider) #11

Jeremy Smithers I have a Snap and power agrees between my V800, all my virtual cycling programs including Zwift.

Have you updated your firmware?

(Philip Amos) #12

This is a really important feature and I’m reluctant to use the Interval mode until its’s enabled as I notice a drift between my power meter and Kickr and like to have all my workouts recorded using the Power Meters for consistency.

Eric, you mention this is on the radar but are you able to give any indication on when we can expect this to be implemented?

(Fernando Jimenez 5656) #13

Another vote for this. Cannot for the life of me get my Vortex power to agree with my P2M

Until this feature is implemented, I (and I suspect many others) cannot realistically use Zwift as an efficient training tool.

For inspiration please look at PerfPro they have tackled this problem already to great effect. 

Eric, is there an estimate for when this feature will be delivered?

(Eric C. (Zwift HQ)) #14

We are looking into it but it will definitely take time. I’m generally not one to give out estimates until there is a solid plan of action because everyone just gets disappointed. No matter how nicely you ask me :slight_smile:

(Fernando Jimenez 5656) #15

Pretty pleeeeeeeeease! :slight_smile:

Thanks for the response Eric. I’ll switch to PerfPro for my structured workouts for the foreseeable future in that case


(Francesc Cruz PACK) #16

It’ a really important feature for Workout Mode. You should put it on highest priority.

(Bogdan Urma) #17

My original post/feature request was almost six months ago if you read the first post and the link in it. If Zwift were serious, it would have been done by now. I wouldn’t hold my breath. They are an entertainment package - use TRAINERROAD for workouts. 

(Fernando Jimenez 5656) #18

Unfortunately for anything longer than a one hour trainer session I need some form of entertainment or else I’m too likely to cut the session short.

I wouldn’t be so harsh on the Zwift guys though, they have been pretty busy getting the platform out there. While this issue is MAJOR for serious training, instability in the platform was also a deal breaker, and I’ve noticed things have become much more stable as of late. And the recent addition of custom workouts was also a requirement for serious training.

However, as you rightly say, as long as this feature is not implemented, it’s better to look elsewhere for a proper training tool.

To Zwift/Eric, please make sure you announce this feature once implemented!!


(A rider) #19

(Fernando Jimenez 5656) #20

Hi Eric

Yes, you’ve gone a bit off topic, but I think what Bogdan meant is that you cannot have a proper structured workout without this feature. Sure you can sweat like a pig and discover a new world of pain as things stand today, and sure you can get some training benefit out of that. But that’s no different from following unstructured training. It works, just not as effectively as a structured training plan

Personally if I want to have a unstructured and potentially eye balls out training session I rather ride outdoors (unless it’s snowing).