Q factor and mismatching power meter/crank

I’ve been thinking about getting a 4iiii 105 left side power meter for my GRX crank, but because the GRX crankset has a wider q factor, the left side pedal will be closer than the right. I’m currently running Shimano SPD 540 pedals. Do you think this would present an issue (knee pain maybe?)

Would it make sense to shim the crank out a bit, and if so how far can I do that safely? Is there a way to move the pedals outboard a bit too?

I currently have a Stages GRX left side PM but have been having issues and working with Stages for a resolution. I’m just thinking ahead to plan B.


Pedal washers would be my vote. 2 of these would get what you need for offset.


But you need to make sure you still have 11mm of thread engagement with the washers installed.

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you can always throw a couple of these on the left side:

I’d be hesitant to use more than 2-3 as then you have 2-3mm less threading on that crankarm. But that, and or (maybe) moving your cleats in a bit, could make up the difference.

Side note, what’s the problem you’re having with the Stages Left Side GRX PM? I have the same one, and it’s been great.


hah, Chad beat me to it.


Thanks Chad!!!

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Thanks for the tips!

Using my Kickr as a baseline, I checked my 4iiii 105 power meter against the GRX. The 4iiii is within 3% of my Kickr, but the GRX is consistently 14% too high. I received a replacement from Stages and found the exact same issue. I’ve sent them a bunch of data and their engineering team is looking into it now.

I’ve never had an issue with dropouts or anything like that with the Stages PM, but I don’t trust it! Believe me…I wish my FTP was 14% higher haha.

Ah, I definitely would’ve noticed that kind of discrepancy (I’m absolutely not 14% higher :slight_smile: )