Power mismatch -- Wahoo Kickr vs Stages Cranks

Ok, very quick customer service by Stages and I’m back in business. Took me a while to get set up properly though – I was trying to record both the Stages and Kickr power output on the Element Bolt, but the Bolt kept taking control of the Kickr from TrainerRoad. I didn’t select a workout in the Bolt, but I couldn’t figure out how to have it just record the power from the Kickr and not take control. So, I ended up unpairing the Kickr from the Bolt and just recording the Stages power output on the Bolt.

Then, I has a problem that I was only getting half the power reading from the Stages power meters. For example, if TrainerRoad requested 150 watts from the Kickr with power match on, it would settle on a power output reading or 75 watts. The Kickr output was at least 150 watts. After much finagling around, I found that having the gyroscope turned on on the right crank, was preventing the right crank from sending its power reading (or sending zeros). If I turned the gyroscope off, everything was back to normal.

It must have taken my 2 hours of experimentation before I finally got everything working properly. The pattern I had seen with my previous cranks was also present on these. In ERG mode on a TrainerRoad workout, the Stages power was 10% or more less than the Kickr power. In SIM mode, the two readings seemed quite a bit closer.

I deposited 5 .fit files in the Google drive folder shared with you. Three are associated with a TrainerRoad ERG mode workout (Monitor+1, which maybe wasn’t the best choice, but that’s what I had on tap for today). They should be labeled well enough for you to identify what they are. Of the 3 ERG mode files, the TrainerRoad file should have the Stages power, the Zwift file will have the Kickr power, the the Bolt file should also have the Stages power. (I included the Bolt file because I don’t know if the TrainerRoad file has the L/R % data in it.)

For the 2 SIM mode files, the Zwift file will have the Kickr power and the Bolt file will have the Stages power. It was difficult to hold a steady power/cadence on this ride as the terrain (NY central park loop) was very rolling. Then instead of concentrating on the task at hand, I got caught up in trading pulls with the red jersey holder to turn a good time and take 2nd on the loop. The second lap I tried to be more steady, but just like outside, that’s difficult to do in SIM mode. There are a couple of sprints in there as well.

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Update. New, interesting data after reading the thread on big vs. small ring (Big vs Small Chainring - Same Power (ERG Mode Gearing) - #241 by mcneese.chad).

I have been doing all my TrainerRoad ERG riding in the big ring. After reading that thread, I decided to try doing today’s workout (Antelope) in the small ring, except for the last interval, which I did in the big ring.

Well, guess what? The Kickr and Stages power levels seemed to match when doing the workout in the small ring. The big mismatch came back in the last interval, where I switched back to the big ring. I have uploaded the TrainerRoad file (Power match Stages power), Zwift file (Kickr power), and Wahoo Elemnt file (Stage power) for this workout.

Big ring was 53-14 or -15 and small ring was 39-17 or -19.

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I see similar things with my Kickr Core and Pioneer PM (left only). I train 99% in small ring now. If I get out of the saddle the power differences are even bigger

Arrgh, more riding and more “weirdness.” Using the small ring doesn’t result in the same power from both sources anymore. Don’t know why not, but the same old discrepancy has cropped up again. After re-watching your videos and all the supporting info, I tried use Right only, then Left only power from the Stages meters. As expected, the Right only power seemed more different than the Kickr power and included some larger drops in power of short durations (kind of erratic).

I was hoping that using the Left only Stages power would provide a better match with the Kickr, but no joy. It was still consistently off (lower) in ERG mode, though it seemed to match well in SIM mode on Zwift. I haven’t checked whether there is still any difference at all in the power level comparison when using the the large chainring.

I don’t really care for the larger fluctuations in power from the Stages power meters when using PowerMatch with Trainer Road. So, I think I will go back to using Kickr power in the future when it’s time for another FTP test.

I’m not sure if you have tried this yet, but I was have a similar issue with my Stages and Kickr and here’s what I did to fix it.

I pair my Stages and Stages only to Zwift.

Then I pair the Kickr and Kickr only to TR in ERG mode.

So Zwift is getting readings from the Stages and TR is getting readings from the Kickr.

What I then did is opened up the Wahoo Fitness app and there’s a box where you can type in the ANT+ ID for your Stages power meter. After I did that, the Kickr seems to pull the power readings from my Stages and report those to TR as if it was the Kickrs power reading.

After I did that, the power I see on my TV for Zwift and the power I see on my phone for TR are dang near identical.

This is very interesting. You are not the first one that says the setting “control w/Ant+ Power Meter” in the Wahoo app works. I have had this setting turned on for a year now and I can say with certainty it doesn’t work for me. My power is off by over 5% to 6% at times and well within 1% at other times. It’s a huge frustration for me because I don’t like using power match. I wonder if the reason it doesn’t work for me is because I use TR with a laptop. Maybe the trick is using the same phone the Wahoo app is installed on to run TR. I will have to try this.

Here’s a comparison I did with my setup and there’s a slight lag that’s visible and I think the graphs are slightly misaligned. However, the key take away for me is that there’s a .25 watt difference between the file as reported from the Kickr and TrainerRoad vs as reported by Zwift and the Stages.

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It was inconsistent for me, so I gave up and went with TR’s PowerMatch. IMHO the side benefit is that PowerMatch feels more like riding outside. Even with PowerMatch on, the “larger power fluctuations” are actually “smaller power fluctuations versus outside” and so I’ll say to each their own.

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Actually you have a great point and I have thought about that. It’s those freakin times I’m already at my mental limit only to see my power is fluctuating 20 watts high :nauseated_face:. On longer intervals I do think I might give power match another try.

I did intervals outside before signing on to TrainerRoad, and so it all seems so much easier on the trainer. Without PowerMatch, Erg mode on my wheel-off Kickr 2017 felt unnatural and I hated it. Much rather have indoor training feel like outside, than make picture perfect interval graphs (and turn off Kickr power smoothing too!).

They ought to be dang near identical. You are pulling power from your stages PM for both Zwift and TR. I could see doing that if I believed that the Stages power was more “correct.” However, I don’t believe that is true.

You said you are using PowerMatch within the Kickr interface. Isn’t it then just effectively getting power from the Stages power meter? There may be a slight lag because of the PowerMatch and maybe also due to other timing differences, but you really aren’t comparing Kickr to Stages, you’re comparing Stages to Stages Power Match.

The power fluctuations outside are unavoidable due to changing terrain, wind, road surface, etc. That’s precisely why indoor training is advantageous – so you can better control with consistency the power level/cadence/etc. for targeting specific areas for improvement. If you’re just trying to match outside riding, go ahead and go for what you think feels best.

I agree that the large power fluctuations I was talking about are small compared to outside riding. They also aren’t that big a deal for hitting the goals of the workout. It’s mainly just a distraction/mental thing that makes me feel like I need to do something to even the power out even though “doing something” is usually detrimental because the fluctuations are random and not caused by fluctuations on my part.

To each their own. ERG mode feels essentially the same to me with or without PowerMatch. As I said before, it isn’t meant to match outside riding; it’s meant to consistently attain and hold a specified power level. If you want to better match outside riding, don’t use ERG mode at all!

I am more concerned with the accuracy of the Stages L/R power meters on Shimano cranks when riding in ERG mode, as reported by Shane (GPLama) and others, than in matching outside interval “feel” or even in the more variable power readings I am seeing on the Stages.

If I believed the Stages power was more accurate, that’s what I would go with (and what I dud switch to after first investigating the power level differences between Stages and Kickr. My decision was also influenced by wanting to have consistency between indoor training and outdoor riding. After further research, I now coming around to believing that in ERG mode, the Kickr power level is probably more accurate than the Stages power meters on Shimano cranks. That is why, in the next training block, I will be switching PowerMatch back off and going with the Kickr power level.

Well that’s exactly the point. Using the kickr as the power source would be a bad idea as it’s not an option while riding outside. By using the stages as the power source inside and out I’m getting accurate comparable data that I can review. If I was comparing my outdoor rides with the stages to my indoor rides in my kickr the data points would be meaningless.

To say which is more accurate representation of a watt is kind of a useless point. At the end of the day all that really matters is that I’m training to the same power source all the time so that I can see changes in my fitness overtime. I really could care less how my power figures compare to others.


Not exactly. As I said, in SIM mode or Resistance mode, the two power levels match pretty closely. It in only in ERG mode that the power levels differ significantly. (Note: this is with the battery removed from the R side Stages meter based on GPLama’s work showing issues with measuring power on Shimano right side crank arms). So, I believe I do have consistent power levels inside to outside, much more consistent than if I used Stages power in ERG mode inside.

Trying to use a “more accurate representation of a watt” isn’t entirely useless. It isn’t useless for people with different power meters on different bikes, or migrating to different power meters over time. And it isn’t useless if you want to have a more accurate representation of yourself in online races and rides, such as on Zwift.

Please forgive me ahead of time here for the length of post.

From my prospective, my training and progression was going well using TR, then just after a Ramp test with a 220 result, I got my KICKR and all has gone out the window and my legs are beat just trying to figure out how to make it work and be consistent and have good training sessions.

I’ve been using a PowerTap wheel and a Stages L only and those are relatively close and easy enough to adjust between trainer and outside if I went outside.

With the new KICKR, it is so far out to lunch it is ridiculous !!! especially as compared to previous results.

In PowerMatch auto, I cannot complete a workout with any real Threshold or SS load, my rpm drops too much and the spiral is unstoppable. If I then switch to resistance mode, I am able to put out or at least really close the suggested watts and rpm to finish the interval or workout, as long as I use my Stages output watts reading, but the KICKR will be reading at least 20-30 watts less in the Threshold range and more in the SS range.

I tried lowering my FTP by 15% and that was not nearly enough. On the last FTP test, I’d just gotten a 10% gain after 5 weeks of SS MV p1 with a lot of extra endurance hours giving me 21 to 22 hours a week on the trainer.

Even in resistance mode the Stages L is 10 to 30 watts higher than KICKR indicates

Thanks for letting me vent some!

The replacement KICKR got to me and it seems to work better at least at low power and upper level endurance efforts. Still more testing to go. With this KICKR in ERG Auto, it was much easier to bring the cadence back up after some low cadence standing efforts, but could not get it below 60 rpm very well standing in ERG Auto.

The replacement KICKR needed a firmware update. Calibration would work on TR but I had a hard time getting calibration to work using Wahoo App, but it finally worked.

I had nothing but problems with my 2018 Kickr and Stages power cranks. I tired to have Stages dictate the Kickr resistance but found a lot of drifting power as the Kickr warmed up. Whoever decided that smart trainers don’t need thermal compensation should be fired. Putting 200-300W into a trainer turns into heat in the resistance system. You can calibrate a Kickr after “warming it up” but it assumes a consistent input. Ended up selling the Kickr after a few months and going back to my eMotion rollers and Stages power.

:scream: I have just picked up a new Kickr18 on Friday and seem to be experiencing the same issue. After two rides it just doesn’t feel right compared to my old Tacx I-Genius wheel on trainer. I tested it today against my 4iiii Powermeter on my outside bike and it was a good 30-35 watts less when riding around 235-240w. I’m a bigger rider with a current FTP of 310w (although doubting this now :grimacing:) so normally 235w both inside and outside is a walk in the park, but it was a struggle.

Question is do I suck it up and re test on TR with Kickr and that becomes my baseline for training and TR workouts and know that external rides won’t be the same Or is it a dud unit and send it back for a replacement?

@tonyrg I would be interested to know how you have got on with your replacement and how much convincing to had to do to get one out of Wahoo? I’ve seen references that the support leaves a bit to be desired.

I love the Wahoo brand but in the back of my mind I’m wondering whether I should just return it and go for a Tacx Neo.

Thanks in advance