Stages PM (and warranty replacement) consistently high

Hi everyone! I know there was another thread about GRX power meter options, but I was hoping I could get some input from folks who have already have a Stages GRX power meter or had similar issues with another left side PM.

Stages did a factory install in my GRX 810 48/31 crank. I decided recently to compare it to my Kickr and my 4iiii left side 105 power meter on my road bike to see how close they were (if at all!). I calibrated my Kickr Core by riding for 15 minutes then doing a spin down, then tried my 4iiii power meter on my road bike (Canyon Endurace) , the same power meter on my Cannondale Topstone, and then the GRX power meter on my Topstone. I recorded the Kickr Core output via TR to my tablet and the power meters to my Wahoo Elemnt.

The 4iiii was consistently 3% over the Kickr Core when installed on both bikes. The GRX power meter was 14% higher than the Kickr Core so 11% higher than the 4iiii.

Stages sent me a warranty replacement and I have the same issue. I just let them know this, along with sending the .fit files so they could see the raw data again. Stages support has been great so far so please don’t interpret anything here as bashing the company!!

Has anyone run into something like this? The tests I did a few weeks ago were pretty similar to today’s results, so it seems everything is reading consistently if not 100% accurately. I’m not crazy thinking the Stages is too far off right?

The Stages that I owned was consistently high (outside the expected norms) and constantly got power spikes that could never be resolved through talking with Stages.

This is my own personal opinion, but I’ll likely never own a crank arm based power meter ever again. The spider based units are definitely heavier, but they’ve been way more consistent for me.

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