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Front derailleur rubs crankarm

Old 03-31-21, 06:18 PM
  #1  
JohnUSA
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Front derailleur rubs crankarm

I put a Power2Max edition gravel power meter crankset on my 2021 giant revolt. It was advertised as a drop in replacement for my GRX crank.

However, Iím running into problems. The GRX front derailleur rubs against the inside of the power2max crankarm when the front derailleur is in the big ring.

Iím a fairly experienced mechanic and know how to adjust front derailleur. Itís set for the right height, itís aligned properly, etc.

If I adjust the front derailleur so thereís no chain rub on the front derailleur when in the hardest gear (in my case 46x11), the front derailleur cage rubs against the crank slightly.

Likewise, if I adjust the front derailleur to clear the crankarm, I get chain rub when in 46x11.

To be clear, I tried a 105 front derailleur as well and I have the same issue, so it isnít a GRX-Crankset incompatibility issue.

My best guess is that the clearance between chainring and crankarm isnít large enough. Is there a way to put a spacer between drive side crankarm and chainring? Itís a rotor crankset, so both crankarms come off the spindle and the chainring spider fits on splines on the spindle.

What should I do?

Thanks,

John
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Old 04-01-21, 09:40 AM
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freeranger
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I don't know much (anything) about GRX, but I was curious after reading your post. I found this, don't know if it will help or not, but thought I'd offer it up: "You do have to be careful about front derailleur and crankset compatibility though – GRX uses a +2.5mm chainline, so Shimano says you need to run the GRX front derailleurs with GRX cranksets, and road front derailleurs with road cranksets."
I found that here:
Shimano GRX component series is the first dedicated gravel group w/ 10 & 11 speed options - Bikerumor
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Old 04-01-21, 09:42 AM
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Funny but this seems like an ideal post for the 'bicycle mechanics' section of the forum, not GD.
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