[junglejim86]

Can I mix and match ultegra r8000 and GRX crank arms? I know I CAN but is there a difference in offset on the non drive side? I've been googling for a bit now and can't find exactly what I'm looking for.

thx

 

[jrob300]

I use a 105 Stages PM left arm with my GRX crank. IIRC, the Q factor on the 105/Ultegra is 6mm narrower (3mm/side), so I put a few Wheels Mfg. spacers under the arm before installing. It doesn't make up the whole 3mm, but works great.

 

[jimoii]

I use a 105 Stages PM left arm with my GRX crank. IIRC, the Q factor on the 105/Ultegra is 6mm narrower (3mm/side), so I put a few Wheels Mfg. spacers under the arm before installing. It doesn't make up the whole 3mm, but works great.
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[jimoii]

Thank you, all useful information for me

 

[Pipeliner]

I’ve got a 4iiii power meter 105 crank arm on my GRX 600 crankset with no spacers. Clears the frame by a couple mm. Works like a champ. If you have a GRX 800 crankset, the Ultegra crank arm will balance better because they are lighter.

 

[jrob300]

If you have a GRX 800 crankset, the Ultegra crank arm will balance better because they are lighter.

Using the Stages 105 left arm saved me well over half the weight increase from Ultegra 8000 to GRX. I could not believe how heavy that GRX left arm was.