Powermatch and actual trainer mode

So to clarify what powermatch is doing:

Which of the following is true?
In either manual or auto powermatch modes

  1. power meter data used to drive the smart trainer in RESISTANCE mode (ERG control law in the TR app)
  2. power meter data used to drive the smart trainer in ERG mode (ERG control law in the smart trainer)

I get that powermatch either derives the power offset (auto) or uses a constant offset (manual) from the on-bike power meter compared to the smart trainer power meter, but from my Wahoo Kickr’s perspective, is it in erg mode or resistance mode when using power match?

Thanks!
Collin

Full TR info in this post:

To your questions:

  1. Power meter data doesn’t “drive” anything other than the display when you are using Resistance Mode on a smart trainer.
  2. Yes, this is correct.
  3. Your Kickr is in ERG mode if you have TR set to ERG mode. It is a direct connection.
    • The variation from PowerMatch is which device TR uses for power data (Trainer vs Power Meter).

PowerMatch only applies to the trainer in ERG Mode use.
PowerMatch is not used in Resistance Mode in any way.

1 Like

Hopefully a TR engineer can chime in.

To clarify:

When doing a workout in TR using powermatch in TR erg mode with a stages power meter and kickr trainer, from the trainer’s point of view, is it in resistance mode being continually changed by the TR app to hold power based on stages data?

Or

Is the kickr in erg mode and the target power being continually changed by the TR app to hold stages power?

I think it’s the first scenario.

Thanks!

Not a TR engineer….

When in ERG mode, the Kickr resistance is being changed so that the power source (i.e. Stages) matches the target power.

No! Target power is target power. Target power is fixed according to the workout you choose.

Hey, TR agent here :slight_smile:

Resistance mode is by definition a fixed mode. When using Resistance Mode, you are fixed to a set percentage of resistance, and any increases or decreases in resistance require manual input from the user (gear or RPM changes).

PowerMatch works by creating an offset between your power meter and electronic trainer. This offset dictates how much resistance is provided by the electronic trainer to meet the target power. In other words, it does exactly what ERG mode does, but with a second set of logic (the offset) that adapts what the trainer “thinks” is the power, to what the power meter “knows” is the current power. This is used to more accurately adhere to the Target Power of the workout.

As a general rule, if the trainer is adapting to the Target Power without the user needing to shift, this is ERG mode. Every other mode leaves the user to make changes (RPM or gearing) to match the Target Power.

I hope that clears things up a bit :+1:.

1 Like

Hey @Bryce,

Thank you for the insight here. I’m having a related knowledge issue and haven’t found anything that directly addresses it; I’m just seeking knowledge here. I’ve been using a Wahoo Kickr for about 1.5yrs. I added a Gen 3 Stage (L) PM within the last couple of weeks and am still utilizing ERG mode. I’ve been feeling better, but maybe not as much as the increased performance I’ve been perceiving. When adding a PM, should one re-assess using a ramp test? I did a spin down and have been calibrating the PM before each workout, but my PE seems a little lower. At first I thought I was just crushing the workouts, then I realized it could be a discrepancy due to an equipment change. Can you confirm or refute my hypothesis?

Thank you!

  • Yes. Any time that you change your power measuring device, you should retest with that new device.

The reason is that despite manufacturer claims to precision, there are distinct differences in power measurement between most power devices (power meters and trainers included).

It is common for people to feel that that workouts are “easier” or “harder” after adding a new power device, when they have not reassessed their FTP with the new device. This happens because their new device reads higher or lower than the prior one.

Using PowerMatch helps set the trainer to the right power target to match the reading of your power meter, but it does nothing to actually “fix” the differential from your prior workouts/tests from the older device.

  • Say that trainer gave you and FTP of 200w.

    • You do workouts at that level and everything is fine.
  • Then you add a power meter, and lets say it reads at 210w when your trainer is at 200w.

    • If you use it with PowerMatch, the trainer will be reading 190w when the power meter says 200w.
    • As such, you are getting a 10w easier resistance when compared to the power from the trainer only, at your 200w FTP.

That is an over-simplified example, but actually quite typical. The differences can be higher or lower, so the “feel” to the rider will vary based on that difference.

To reiterate, you should always retest whenever you get a new power measuring device.

1 Like

@mcneese.chad, Thank you! So does this mean I will likely see a different FTP for a fresh assessment with the new device, rather than there being a calibration synchronization?

1 Like

Yes, assuming everything else being equal (and based on your comments about the feel) I expect you will have a “different” FTP when you retest.

I italicized the word above because if you test on one device (your trainer) and also record on a second device (power meter), you will most likely get some difference between the measurements. In some cases they match within the device tolerances, but it almost seems to be the exception.

So, retest, see what your “new” FTP is and use that for your training needs.

  • Keep in mind, that your FTP may not have actually “changed”.
  • What really changed is the “tape measure” you are using to read Watts.
1 Like

Going to piggy back off this response…I have a similar query in a different topic and haven’t got any response yet. Would be great to get your view on it! :slight_smile:

Basically, I’ve done a new FTP test using Tacx Vortex to record the power but also recorded the power from Assioma pedals on Garmin head unit (did not use Powermatch during test).

I got different results for each (higher power from the pedals) and unsure which FTP to use for next training block. I’m thinking I should use the higher one (given your response above which implies that using PowerMatch will make my sessions easier than they should be). Is that the correct way of thinking about it??

You should use the results of the Power Source that you will use for your workouts going forward. If you pair both your Vortex and your Assiomas to TrainerRoad, your Assiomas will default as your power source, so use the results from the pedals.

The only time you would want to use the readings from your Vortex is if you were not going to pair your Assiomas to TrainerRoad during your next training block for one reason or another.

I hope that clears things up :ok_hand: .

4 Likes

Perfect…that’s great Bryce. Exactly the clarity I was hoping for!

1 Like

Hi

I have maybe a stupid question but, if you want to use powermatch in manual mode, do you still need to have your PM and your trainer connected to TR? I have a Direto smart trainer and two bikes, in my tri bike I do have a P2Max PM, but in my road bike I use a PT hub.

Last days I tried to use powermatch in manual mode using my phone, I didn´t connect the PM, and it seamed not to be working. I clarify again, as the offset is constant, I´m using powermatch in manual mode.

Thanks in advance!

PowerMatch only works when both your power meter and your trainer are connected, and ERG mode is enabled. There is no way to use PowerMatch in manual mode, even if the offset is constant because the code it uses does not adjust the power reading, but rather it constantly adjusts ERG commands so that that the resistance matches the set target power.

When you are in manual mode, there is nothing for PowerMatch to do since there are no ERG commands to adjust. We simply display the power readings of the power device with the highest priority. A physical power meter is of higher priority than your trainer, so if both are paired, your power meter will be the primary power source that is displayed on screen and recorded.

I hope this clears things up a bit!

1 Like