This is interesting! I don’t know (yet) if I have an imbalance, but the calculation seems pretty straightforward.
The issue with that compensation formula is it assumes your imbalance stays constant day to day and more importantly at different intensities. This could be close enough to the truth, but very unlikely.
I’m actually fairly consistent with a 46-48/54-52 imbalance regardless of intensity, but I know others who are 45/55 at lower intensity and 50/50 at threshold! So your z2 could be much different than your threshold sessions if you were working off a % of FTP for example.
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Right. Many people think that L/R balance is constant, and it’s not. Here’s a plot where we recorded a single-sided PM and a crank spider PM (i.e., dual-sided). The average power was something like 3% different, so the left panel shows what the data would look like if the SS was constantly off by 3% (I actually don’t remember whether the SS was on the x-axis or the y-axis, but for this purpose it doesn’t matter). The right panel shows the actual second-by-second comparison.
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Your 4iiii power meters have software that allows you to make them all agree. That is the easiest step.
Lots of recommendations for dual sided. When you buy dual power meter pedals, how do you know that they measure equally on both sides? How do you know when just one is faulty or gets banged up and goes out of spec?
I know they can be scaled…but to which value? There’s a big spread between the 2 4iiii meters and the Kickr is somewhere in between 
And the rabbit hole goes deeper…
If you do most of your training on your road bike and you train indoors on your road bike, I’d only use the road bike for most power recordings. Never use the Kickr’s power. Make the gravel bike agree with the road bike.
In the end, I don’t think it matters as long as you have them close enough.
FWIW, I have a Stages and have had much better luck with more expensive retail pack batteries. Previously I was buying cheap oem 10 packs of batteries on Amazon and results were inconsistent. With some fresh retail Duracells, my Stages has been spot on with it’s calibration and it has been more consistent with temperature swings.
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This has crossed my mind with my assioma duos. Like I mentioned above, I’m consistently 46-48/54-52. How do I know one of the pedals isn’t out of calibration that artificially creates the imbalance? Short of actually testing each of them, I’ve noticed when I stand when pedalling my power has to be applied equally and it’s actually hard to not have 50-50. So…I’m not sure if this just happens to work for me, but seems to make sense - my pedals always show 50-50 when standing unless I try to do some wonky movements to create an imbalance. Could be n=1 with no scientific basis….
Correct. My imbalance alters with cadence, intensity, fatigue and the phase of the moon for all I know. After driving myself crazy by constantly altering by a percent here and there I settled on the adjustment which dealt with it at the intensity I ride at the most ie top Z1 through to low Z3. Seems to work for me.
Ditto n=2 - we ought to publish a paper on it 
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Lol. Better than some stuff I’ve read!
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N=1, but I’ve found left side cranks are consistently higher power readings compared to my trainers. I finally gave up on them and got some power pedals and now I’m getting almost perfect parity between my bike and my trainer. It was a significant difference, like 30 watts. Had to swallow my pride and accept they’d been lying to me :).
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At least with Assiomas, you can do a static weight test to see if they are properly calibrated. Also, if you check your L/R balance regularly you should notice if there’s suddenly a significant change, indicating one of the pedals is out of spec.
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Check the pinch bolt torque on the crankarm. When it’s too loose, the numbers will be off.
If that doesn’t work, I’d just use the 4iiiiii App to get the number to match the trainer. That will give you a common calibration even if one of them is more right than the other.
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35 posts in and no one has said the correct answer - use the one that gives you the highest numbers. Your self-worth is directly tied to your FTP…take the biggest number you can!!
You guys are slipping!
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Yes you can. You need a new bike to test out your theory about the imbalance 
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Crank that pinch bolt down a bit more and check the PM again.
Just in case anyone was following along or runs into a simlar issue…
I picked up Assioma Duo Shi pedals and did a quick test ride today, comparing Assioma vs my Kickr Core. They were very close, but my L/R balance is apparently a mess. I guess that’s why the left side 4iiii power meters were reading high vs the Kickr.
This is just a quick section of my ride, but you get the idea 
. I guess I have to knock my FTP down a bit and rely on the Kickr and Assiomas. 4iiii’s might be headed for ebay 
Garmin FIT file is the Assiomas…
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I think you can adjust the 4iiii to match your balance. I only have that and a left sided Favero though :-/