Outdoor PM versus Trainer PM

Hi all,

Since a few days I am the lucky owner of an Stages 105 powermeter for my outdoor bike.
Did some rides and concluded that the power measured is approx 50Watt lower than at the same effort on my indoor Trainer.

Just wondering how Xert is coping with that. Does Xert recognise that there are 2 powermeters with different measurements and compensates for that?
Just wondering.

Gr Johan B

No. Your indoor trainer is? And as I said before, some of the difference can be due to L/R imbalance, but not likely 50 Watts. In my case, it would be ~8 Watts on 100 Watts.

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How did you come up with the 50 watt figure?
Do you feel that number is valid across the full range of watts you generate or is that a top end estimate?
Try a short punchy ERG workout (ex. ‘12 minute workout’) on your trainer with Powermatch enabled (will use Stages meter to apply resistance) versus the same workout without Powermatch (trainer power meter).
How do the two workouts compare?
To use Powermatch pair the Stages device as a power source, then enable Powermatch under the trainer sensor settings (will disable power data from the trainer).

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Thanks all for your replies.
The 50 watt is a rough estimate.
I will try your test but need some time for that.
At this moment I have a dedicated bike on my trainer and the Stages PM is on the outdoor bike.
So I think I will mount the Stages PM on the Trainer bike when I find time for it and perform the test you mentioned.
Keep you posted.

This is why I have pedals, as they are so easy to swap :joy: My old P1’s are on the trainer bike and the Assioma’s on the road bikes; either swap in under two minutes. I sometimes use the P1’s on my spin bike, to calibrate power from that.

Remind me again which indoor trainer you have? I have a Neo, which is so accurate, that I have calibrated my Assioma’s to it. Obviously, in your case, not knowing IF you have a L/R imbalance (unless you have a Neo too) and how much difference that makes, it will be harder to correct.

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I do have a Wahoo Kickr Core.
I don’t believe it is possible to see the different power on each pedal.

I think it isn’t. Re the difference, maybe this may be of interest to you: https://www.trainerroad.com/forum/t/help-diagnosing-stagesl-vs-kickr-power-differences/15564/9 (obviously, there are more topics on this)

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Interesting tread, thanks!
What I understand from it that my feeling that the left pedal Stages seeing differences compared to my trainer is not an incident. Well, I guess I have to buy the Stages right pedal crank also to decrease the differences :slight_smile:

You may first want to find out if that’s worth the investment. You may not even have a L/R imbalance, although it’s quite common. But 49/51 is not really that much of an influence on the average.

Your Kickr Core is maybe not the most accurate, but it’s pretty good, so I would take that as your benchmark. Remember there’s a ~2% accuracy on either device, so a difference of 4-5% is theoretically possible.

Also, riding outdoors frequently leads to a bit lower averages than indoors, because of the (lack of) consistency in power output. You may still feel (RPE) just as tired, but the numbers are lower.

Note that for some people it’s actually the other way around, though less frequently: they just have a hard time because of cooling and hydrating problems, or suffer from the rigidness of the setup.

I have the same problem but with Favero Assioma pedals. These pedals have the ability to incorporate a scale factor into the reported power to bring them in line with other PM’s or trainers. Problem is the Assioma is single sided and my left leg is stronger at low powers but they equalise as the power ramps up and/or I fatigue. This shows my trace of the 2 PMs from the DC rainmaker analyser…

I know stages do not have the facility to incorporate a scale factor. It would be great if someone could write a Garmin IQ field to do that and write the corrected power to the .fit file. Any chance @xertedbrain ? Just like you do on the IOS app

I do not see a solution to that, other than make your Uno a Duo…