Power mismatch -- Wahoo Kickr vs Stages Cranks

It’s not a TR issue, or whatever software is in use. As you say, you tell the hardware to do ‘the thing’, it does ‘the thing’. It’s up to the hardware to be correct.

Having said that…

Shimano Left/Right cranksets are COMPLETE POWER POTATOES.

I’m going to start screaming that even louder now I have a Quarq DZero tested under the same protocols that passed with flying colours, first time, no messing about.

The sooner Shimano redesign their cranks and/or stop others slapping gauges on them the better.

@GPLama As I understand the Shimano problem, left-only 6700/6800 generation cranks are ‘OK’ since they are a more symmetrical design. They avoid both the asymmetric crank arm and the right side spider issues that cause the problems with the current gen L/R. Is this (at least close to) correct?

I have no issues (well, less issues) with quality LEFT only Shimano power cranks. For my rides/testing protocol they give more accurate overall data when lined up against other known-good power sources (AssiomaDUO, P1/P2, V3, Neo, etc). It’s not how it should be at all. Dual L/R should be more accurate… but when the right is a root vegetable, there’s problems.

*This is particularly evident in steady-state ERG where almost everything is constant. Outside and sim mode rides have enough randomness in them to smooth this issue over somewhat… on most meters. I have a few that are RIGHT wrong no matter where I take them.

It’s not that easy. I love my Di2. It’s awesome. I also love the numbers I saw yesterday from the Quarq after MONTHS of junk from other meters.

Edit: Oops, I guess I can’t upload the files here. Hopefully, the link at the bottom will work…

Ok, here are some workout files. I did 2 different rides. First, I warmed up for 15 minutes, then did a Wahoo Kickr spindown, followed by a zero reset for each of the Stages meters. (I thought I used to be able to zero reset both L/R meters from the left one, but it doesn’t work that way anymore. I think I unlinked them (or tried to) a while back to pair the right meter to TrainerRoad for cadence for some reason. I can’t link them back – both meters show as a right side crank. I don’t know if that’s correct, but just letting you know in case separate L/R data are not showing up in these files.)

The first ride was done on Zwift (London course) in SIM mode with the Wahoo Kickr power controlled by Zwift. The file “11_06_19.tcx” was recorded by the Wahoo Fitness app with power from the Stages pedals. The “2019-11-06-11-54-06.fit” file is the file from Zwift with the Wahoo Kickr power.

The second ride was the “Carter” workout (with a higher power section added since this is a lower power aerobic workout) with TrainerRoad controlling power in ERG mode in PowerMatch (using the Stages pedals for power). The file “Carter.fit” is from TrainerRoad with power from the Stages pedals. The file “2019-11-06-12-25-52.fit” is from Zwift during that ride with power (not controlled by Zwift) from the Wahoo Kickr.

In today’s rides, it seemed to me that the offset I was describing previously also occurred during the Zwift controlled SIM mode activity, but was even more pronounced during the TrainerRoad controlled ERG mode activity.


(Attachment 11_06_19.tcx is missing)

(Attachment 2019-11-06-11-54-06.fit is missing)

(Attachment 2019-11-06-12-25-52.fit is missing)

(Attachment Carter.fit is missing)https://drive.google.com/drive/folders/1qYSVB0cF078XpsUaCDsZrufqxZdZggtp

The last Trek Emonda I picked up, I had it configured with Quarq Dzero crank and dura ace di2 drive train. Got the best of both worlds.

Hmmm… Those files from Zwift don’t split out the L/R at all, so they’re not of much use to deep dive into. If you can record all power sources with a Garmin or Wahoo unit, that’s preferred. If not then the Kickr with Zwift/Trainer Road and the Stages L/R crank with an Garmin/Wahoo. This is a pain in the arse, I know. It’s my daily grind.

I use a stages gen2 as part of a 6800 Ultegra arm, but my crank and other components are 8000 Ultegra. Haven’t noticed any problems with fit or offset or anything

Can you use the .tcx file I recorded with the Wahoo Elemnt Bolt? It has the Stages power. If you can use it, does it split out the L/R? I just added a second .tcx file to the shared Google Drive directory. That one matches the ERG mode 2nd ride where the Zwift file has the Wahoo Kickr power data. Note: I started the Element Bolt a bit later than the start of the ride, but I assume you will be able to match them up.

What does the ‘controllable’ box do? Should this box be left unchecked/used if using your stages for power while riding in zwift - doing a structured workout or race, etc?
I have a kicker as well. Just curious.

When mixing TR and Z, you want the Z device Controlled to be empty. That means Z wont be trying to control the train as the same time as TR via your ERG workout.

You only want me app with control access at any time. You just want Z to read power to move your avatar in the game.

The ‘controllable’ tells Zwift you have a smart trainer that Zwift can ‘control.’ If you select your trainer as ‘controllable,’ then Zwift will change the resistance of your trainer to fit the course that are on riding on in Zwift. You can use either your smart trainer or your stages as the power source (your choice).

So, if you are just riding on Zwift, doing a structured workout, a race, or just riding, you want the smart trainer selected in the ‘controllable’ box. If you are doing a TrainerRoad workout, you want TrainerRoad to control your trainer, not Zwift. So you need to leave the ‘controllable’ box in Zwift unchecked in that case.

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It doesn’t look like it. Use the Wahoo Elemnt App to share/export the FIT file. Those are the best when it comes to analysis (that I’ve come across).

Done. The 105 file should be the match to the first ride and the 106 to the second. Still concerned that it may not have L/R date for some reason…

Hmmm. The ANT+ IDs are now there in the BOLT FIT files… but I’m not seeing a L/R split. It is a real Stages Dual L/R crank as per your original post? It’s looking to me like a Stages LEFT only… but I could be wrong. Could the right be missing/flat battery/unlinked?

Arh… wait… I’ve just scanned your reply above. I suspect this is the issue, it’s a single sided power meter at the moment for some reason.

Alright, I was afraid of that. I will try to fix it. If you have any ideas, let me know! FYI, it is a Stages L/R crank with Ultegra R8000 cranks.

*Totally unofficial ideas…

  • Remove both batteries.
  • Short the terminals carefully from +/- for a few seconds… a screwdriver or even the battery can do this. At your own risk.
  • Install two new batteries.
  • Spin the cranks 5 times.
  • Open the Stages Power app.
  • Connect to them / make sure they’re linked / zero them.
  • Check for firmware updates. Do them if there are any.

If nothing works from above, contact Stages Support.

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No joy. Guess I’ll be contacting Stages support. Thanks.
Edit: I just opened a support ticket.

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I heard back from Stages. They don’t have an in-field fix for my power meter issues. They are issuing a warranty replacement – good on them! I’ll try to get the data you requested once I have them installed. In the meantime, although I know you are really interested in the Stages L/R differences, is there anything yo can say about the Kickr/Stages power differences in SIM vs ERG mode from the data I provided?

Thanks Shane!

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Good news on the replacement. Nothing much I can do without a clean/clear set of data with both the L/R split.