Kickr Flywheel Compensation

(Christian Wiedmann [X] 50) #1

I know this isn’t really a Zwift-specific issue, but I wanted to raise the issue of Kickr flywheel compensation because of its particularly significant impact in Zwift.

The issue: I am pretty sure that the Kickr’s power reporting does not take into account the energy going into or coming out of the flywheel. This means that when decelerating, power is overreported and when accelerating underreported. For example, whenever I hit the 1% grade going up the hill on the counter-clockwise loop, my power output spikes from 250 to 360 or more watts even if I keep constant pedal pressure or even soft-pedal. Conversely, I need to pedal really hard to stay over 200 watts when I crest the hill shortly after.

In Zwift, this means it is difficult to ride smoothly with someone who is not riding a Kickr, because I will tend to surge relative to them at the base of hills and lag at the top.

It would be really nice if Wahoo or Zwift added some kind of compensation (e.g. by looking at previous sample’s speed and current speed and doing a lookup of energy difference) to the power number reported to make the reported number more reflective of the actual amount of power that would be applied to the bike under these circumstances.

I’ve reported this issue to Wahoo, but I am not confident they will take action on a report such as this from an end user. I figured at the very least, Zwift might have more leverage with them. If they aren’t willing to fix the issue, it seems like it would be possible to do this on the application side as well.

The irony is that it’ seems like they are already doing a certain amount of processing of delta-v in order to detect coasting. It’s a shame they didn’t go one step further to deal with the flywheel issue in the same way.

(Sadao Ikebe) #2

+1 Exactly same happens on Real Turbo Muin. (with realvideo app). Is it possible to use KICKR as a resistance device but read power from power meter?

(lilmira koyotes) #3

I was thinking the same thing today and it explains why most people can drop me on the start of a descent. I wonder how that would work too if Zwift controls the resistance but takes the power reading from a separate power meter.

(Dave Dixon) #4

I put in a request with Wahoo to fix this flywheel-power issue yesterday, before I found your thread here:

Not sure if you’ll be able to see that, but the response so far is not particularly encouraging.


(Christian Wiedmann [X] 50) #5

I can’t read your request, but the news from Wahoo is actually good. Their latest beta firmware has a fix for this issue. Hopefully it will be released soon. Unfortunately the firmware is password-protected, but hopefully it’s just a matter of time now before the fix is available.

In the meantime I’ve been using the KICKR for resistance only with the power measurement coming from a Power2Max power meter.

(Dave Dixon) #6

Hey, that’s great! How do I get onto the Beta-team?  : )

Here’s my Wahoo conversation: