Are GRX 810 and 820 cranksets the same?

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zachspeed
Posts: 23
Joined: Wed Feb 13, 2013 9:54 am

by zachspeed

Are GRX 810 (11-speed) and GRX 820 (12-speed) the same? Will GRX 810 work with the GRX 825 12-speed group?

harblhat
Posts: 201
Joined: Mon Jul 18, 2011 12:18 am

by harblhat

Arms are virtually the same, chainring spacing is different. 12s rings are closer together. 810 crankset (ie 11s rings) will work with 825 FD but shifting will not be perfect.

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zachspeed
Posts: 23
Joined: Wed Feb 13, 2013 9:54 am

by zachspeed

harblhat wrote:
Tue Jun 11, 2024 2:06 pm
Arms are virtually the same, chainring spacing is different. 12s rings are closer together. 810 crankset (ie 11s rings) will work with 825 FD but shifting will not be perfect.
Thanks. That is what I thought

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pdlpsher1
Posts: 4165
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Location: CO

by pdlpsher1

The chainring spacing difference is 0.35mm, with the difference made on the big ring (less machined cutout such that the big ring sits 0.35mm closer to the small ring).

LainOTN
Posts: 85
Joined: Sat Feb 15, 2020 3:01 pm

by LainOTN

Adding to the comments below, I asked a powermeter brand about availability of dual sided FC-RX820 and the answer was:
We are currently not fitting a double sided one on the RX820 but the RX810 due to the gears being a little thicker and hooking up to our measurement

wannabefast
Posts: 89
Joined: Thu Mar 04, 2010 6:50 pm

by wannabefast

Actually the arms are just virtually the same, they are exactly the same. Even has the same part number. The chainrings spacing are slightly different, though, as others have stated.

zachspeed
Posts: 23
Joined: Wed Feb 13, 2013 9:54 am

by zachspeed

wannabefast wrote:
Thu Jun 13, 2024 2:37 pm
Actually the arms are just virtually the same, they are exactly the same. Even has the same part number. The chainrings spacing are slightly different, though, as others have stated.
Does that mean, that if you take the 810 arms and put on 820 chainrings, you have an exact 820 crankset?

Nomadmax
Posts: 15
Joined: Wed Nov 01, 2006 12:41 pm

by Nomadmax

Can you use the new 12 speed double crankset on an otherwise 11 speed GRX drivetrain?

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pdlpsher1
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by pdlpsher1

zachspeed wrote:
Fri Jun 14, 2024 9:56 am
wannabefast wrote:
Thu Jun 13, 2024 2:37 pm
Actually the arms are just virtually the same, they are exactly the same. Even has the same part number. The chainrings spacing are slightly different, though, as others have stated.
Does that mean, that if you take the 810 arms and put on 820 chainrings, you have an exact 820 crankset?
Yes.

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pdlpsher1
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by pdlpsher1

Nomadmax wrote:
Fri Jun 14, 2024 10:29 am
Can you use the new 12 speed double crankset on an otherwise 11 speed GRX drivetrain?
Yes.

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Nomadmax
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Joined: Wed Nov 01, 2006 12:41 pm

by Nomadmax

Thank you!

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