Any Stages 3 dual-sided users seeing one side inaccurate?

I have had a few power meters - A set of Assioma Duo-shis, two Quarqs, Flux 2 trainer, Neo 2T trainer, 4iii left side meter and they’ve all agreed within 1-2%.

I recently got a new bike with Shimano and opted for Stages dual sided R8100 cranks based on the excellent @GPLama review.

I’ve found they are a good 8-10% over all the other power meters I have, with the left reading significantly higher than the right. Which is funny, because even in the review video GPLama mentions having to “mess around” a bit to get them reading properly, without alluding to what was done.

I’ve refitted to spec twice, updated firmware, zero’d countless times, changed batteries three times and even reached out to Stages support with no response since November.

I thought I’d reach out on a few forums to see if anyone else had experienced similar and found a solution?

Is the left crank installed to spec with a torque wrench? (12-14Nm from memory. Tightening both sides evenly until they reach correct torque).

Now for the left field and likely problem…. What % charge are the batteries reporting on each side? Can you test with batteries that report between 40-85% capacity?


Yep, 12Nm was the figure I used, from memory.

I’ve tested with various batteries, because I’d read that voltage heavily effects the output. Nothing used though.

I’ve just put two new Duracells in there with nearly identical voltage. Interestingly the same issue straight away after just a zero, then unpairing Left and Right, repairing and re-zeroing seemed to improve matters vastly - reducing the average discrepancy over a few minutes from 8% down to 2.5%

Old Batteries were reporting over 90%. I’ll see if I can put a load on them to get that down a bit and see what happens.

Thank you, I appreciate the suggestions!

Ok, found some more depleted batteries from other devices - 67 and 76% respectively.

No change;

After repairing, but 100% battery:

67 and 76% battery:

Within 2.5% seems tolerable compared to the 10% I started at, assuming that sticks. Possibly the best I can hope for?

Left still seems to be reading high, perhaps I’ll put the lower power battery in the left and see if that levels up.

What a faf! I wish Quarq/SRAM would make a 160mm 8 bolt crank so I could fit a Quarq PM.

Interestingly, I had a thought today about 2mm pedal spacers that a bike fitter fitted last year and despite having longer axle pedals anyway, wondered if the washers may have a significant impact on how torque is applied to the arm.

Hoping it’s not just a one off, but removing them has been a huge improvement. Difference was <2%, which is much closer to my other meters when compared wit hthe trainer.

Left is still reading higher, but at least the total power is aligned. Left battery is fairly low, I just hope this doesn’t all unravel again when I change the battery :joy:


I have the same problem. I have Stages dual sided PM Ultegra R8000. It worked fine for 4 years, now over night the calibration value on the R side changed fron 890 to 850 and my L/R balance changed from 49%/51% to 43%/57% in favour of R side. The R side is obviously reading too high. My bike might have fallen in the garage on the R hand side, because my rear derailleur hanger was bent. Could this be the reason for inacuracy and how to fix it?

Many thanks for the answers.

I’ve posted this in several topics over the last few years as a PSA.

The performance and reliability of my Stages gen 2 improved dramatically after I started using fresh, retail pack batteries (Duracell, Engizer, Panasonic). It has to be a retail pack and not an oem pack.

I had been previously buying inexpensive 10-20 packs off of Amazon on the theory that all CR2032 batteries are mostly the same. I guess they aren’t! I even had some oem Energizers that were some of the worst. Maybe fake Energizers?

The retail pack batteries seem to last twice as long so the cost is not much different.

The cheap batteries still work find in all my other devices (sensors, HR monitor, etc).

In sum, try quality batteries and a factory reset on the Stages.

Thanks for your quick answer. I allready did a factory reset and put in a new batery (VARTA), nothing has changed still R side is reading high.

What about removing the whole crank set and reinstalling it? Does it make any sense, regarding the impact on the R side of a drive train when the rear derailleur hanger was bent?

Since it’s a Shimano hollowtech crank it might be worth getting it looked at to see if it’s started to delaminate?

Will do that, it’s a good idea.

I took of the crank set and inspected it. It’s in a perfect condition no signs of delamination. I put it back on using the torque wrench and R Stages power meter stil reading too high.
I took the batery out an now I’m using the L PM only.

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