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GRX RD-RX810 Max cassette in 1x?

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GRX RD-RX810 Max cassette in 1x?

Old 02-06-20, 02:09 PM
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ChinookTx
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GRX RD-RX810 Max cassette in 1x?

Does anyone know what is the max cassette size that can be run with a Shimano GRX RX810 rear derailleur in 1x?

I'm considering a bike for my son that comes with 2x GRX, but might toy with changing it to 1x. I already have a 40T cassette and a wolftooth single chain ring on a bike I'm not using much.

Shimano docs say "Low sprocket: Max. 34T/Min. 30T", and "Total capacity: 40T". Whatever that means. Is the 40T capacity the difference between big chain ring up front and small cog in the back? I guess it's a moot point if the largest cog in the back is only 34?

Thanks!
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Old 02-06-20, 02:14 PM
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dsbrantjr
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Total capacity is (front big - front small) + (rear big-rear small) it is the total amount of links the derailleur can take up without the chain going tight or slack.
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Old 02-06-20, 02:30 PM
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ChinookTx
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So for 1x the front is 0? Front Big - Front Small = 0, then say an 11-40 would be 29T?
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Old 02-06-20, 02:33 PM
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capacity is not the issue, clearance to the 40t is the only hangup. I got an rx800 to work with a 11-40 though so I bet the rx810 would too with the b-screw all the way in
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Old 02-06-20, 02:47 PM
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I emailed Wolftooth to see if their Roadlink DM will work with this specific model. I'll post the answer here.
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Old 02-06-20, 04:22 PM
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Originally Posted by ChinookTx View Post
So for 1x the front is 0? Front Big - Front Small = 0, then say an 11-40 would be 29T?
Yes, the derailleur would need to accommodate 29 teeth. It will still have a large cog limit, you need to satisfy both.
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