Wide range 2x GRX

9 replies · 683 views

wanderer
32 posts
#1Jun 6, 2023, 5:07 PM
Is there a Shimano GRX di2 RD that is capable of 11-42 with stock chainring?
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Angstrom
181 posts
#2Jun 7, 2023, 8:54 AM
https://bike.shimano.com/en-US/product/component/grx-di2/RD-RX817.html
Looks like the RD-RX817
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TimmyR
147 posts
#3Jun 7, 2023, 9:15 AM
Angstrom wrote:
<a href="https://bike.shimano.com/en-US/product/component/grx-di2/RD-RX817.html" target="_blank">https://bike.shimano.com/en-US/product/component/grx-di2/RD-RX817.html</a>
Looks like the RD-RX817
RD-RX817 is technically for 1X up front according to Shimano. The standard 2X counterpart is the RX-815. If you are trying to max it out beyond Shimano's recommendations, check out the videos on the subject by Jom...The Gravel Cyclist. I am pretty sure he's shown the ability for it to get to 11-40. I do not recall if you can get 11-42 or not. I think the key is to then limit the shifting to ensure you do not go to the extremes (large chainring-large cassette or small chainring-small cassette)
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RideWithPride
96 posts
#4Jun 7, 2023, 9:45 AM
11-40t easily works on a 2x grx(di2 or regular) while 11-42t according to a few sites said shifting was tricky to get to the 42t. Shifts a hair better with a roadlink.
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wanderer
32 posts
#5Jun 7, 2023, 10:55 AM
Thank you all. I recall seeing a video on this but could not remember where. And, being outside of Shimano's recommendation, nothing on their site. I have 11-36 cassette now but fully loaded on challenging climbs it sure wicked help to have a couple of more teeth in the back!
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RideWithPride
96 posts
#6Jun 7, 2023, 11:21 AM
3rd party cassettes like garbaruk and sunrace would have options. Alternatively you could go with smaller chainring setup like 46/30 or 44/28.
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TimmyR
147 posts
#7Jun 7, 2023, 12:35 PM
wanderer wrote:
Thank you all. I recall seeing a video on this but could not remember where. And, being outside of Shimano's recommendation, nothing on their site. I have 11-36 cassette now but fully loaded on challenging climbs it sure wicked help to have a couple of more teeth in the back!
I don't think I'd ever be unhappy to have more gears. I'm just now running GRX Di2 with 48-32 in front and 11-34 in the back. Once I get thru this year, I ask going to explore a wider cassette range. I am still getting used to the Di2 upgrade on my Diverge.
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ccand51997
265 posts
#8Jun 7, 2023, 5:36 PM
I run an XT di2 rear to easily get that size. I have to run an XT front, of course, but it handles the 16 tooth jump I use, though going up is a bit rough. I don't run a 48, though. I've read that plenty of folks use the 817 di2 1x in a 2x set up and it will do everything but run full synchro. I've run 46x42 with mech derailleurs, but that requires a lot of chain and limits your small chainring options to about half the cassette.
My climbing road bike with big tires also has an XT rear di2 but I just run a front cabled derailleur.
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Pipeliner
129 posts
#9Sep 7, 2023, 11:54 AM
I ride a 2x GRX with a 36t SRAM cassette. Much better gearing than the Shimano 11-34. Better spacing and better low end.
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Zurichman
1,526 posts
#10Oct 23, 2023, 3:51 PMedited
Shimano is conservative in their cassette ratings. I have been running the 11-40 on the rear of the GRX 810(mechanical) for about 3-4 years. The only gear it doesn't like is the high ring low gear as it grinds or makes a little noise there when you upshift. Shifting is clean though and I don't stay there long. I have also stayed there for some time as I have a hearing loss. lol

Zman
0

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