shimano grx

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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clynch
Posts: 13
Joined: Sat Feb 11, 2017 4:59 am

by clynch

pemo wrote:
Wed Aug 28, 2019 8:30 pm
I am planning to get a 1x11 di2 groupset but I can only find full groupset with RX817 RD (instead of RX815) which is designed for a min. 40 low sprocket.
Do you known if it may work with a 36 or a 32 sprocket ? I do not understand why it would not work since it also work with a 11 top sprocket.
Thanks for your help
I don’t think it will. The GRX derailleurs are specified for 1x and 2x. The reason it wouldn’t work would be that the 817 has a longer cage and won’t keep the correct tension for a cassette that only goes to 32 or 36.
2019 Lynskey GR270, 2016 Specialized Allez DSW, 2015 Niner BSB 9 RDO, 2014 Trek Domane 5.2

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ultimobici
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by ultimobici

clynch wrote:
pemo wrote:
Wed Aug 28, 2019 8:30 pm
I am planning to get a 1x11 di2 groupset but I can only find full groupset with RX817 RD (instead of RX815) which is designed for a min. 40 low sprocket.
Do you known if it may work with a 36 or a 32 sprocket ? I do not understand why it would not work since it also work with a 11 top sprocket.
Thanks for your help
I don’t think it will. The GRX derailleurs are specified for 1x and 2x. The reason it wouldn’t work would be that the 817 has a longer cage and won’t keep the correct tension for a cassette that only goes to 32 or 36.
The other thing to bear in mind is that the mech is likely designed to follow the wider ratio cassette. So, if you mate it with a cassette that is closer ratio, the mech may be too far away from the larger sprockets giving a vague shift on lower gears.


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Curious George
Posts: 265
Joined: Fri Sep 08, 2006 11:48 am

by Curious George

Curious George wrote:
Thu Aug 08, 2019 9:01 am
Shimano has confirmed the GRX Di2 levers will not have the additional buttons as per the current generation of Di2 levers for those interested.
Apologies, this advice from Shimano Australia is incorrect (Not surprised they care about the fishing side more).
The levers do have the additional button. Watch Gravelcyclist's youtube video of a walkthrough of the groupset.

TurboKoo
Posts: 568
Joined: Wed Oct 29, 2008 7:55 pm

by TurboKoo

That’s correct. Additional buttons are on the inside of the hoods, not on top. Feels like they are nicely reachable.
Scott Foil
Shimano 9150
Shimano FCR-9100-P
Shimano C60 tubulars

Aeo
Posts: 147
Joined: Wed May 25, 2016 2:06 am

by Aeo

Feels like this is a good maiden effort.
This groupset will really shine after Shimano makes their full switch to 12sp:

  • Servowave brake levers also on mechanical
  • Hyperglide+ cassette and chain
  • viable 1x with 12 gears / 10T low sprocket
  • Direct mount 1x crankset

I imagine they need more space for Servowave, so only in a Di2 lever. Probably possible on the left shifter on a 1x system but that might be too weird.

TurboKoo
Posts: 568
Joined: Wed Oct 29, 2008 7:55 pm

by TurboKoo

Aeo wrote:Feels like this is a good maiden effort.
This groupset will really shine after Shimano makes their full switch to 12sp:

  • Servowave brake levers also on mechanical
  • Hyperglide+ cassette and chain
  • viable 1x with 12 gears / 10T low sprocket
  • Direct mount 1x crankset

I imagine they need more space for Servowave, so only in a Di2 lever. Probably possible on the left shifter on a 1x system but that might be too weird.
Servowave also on 800-series mechanical, not on 600-series.
Scott Foil
Shimano 9150
Shimano FCR-9100-P
Shimano C60 tubulars

Aeo
Posts: 147
Joined: Wed May 25, 2016 2:06 am

by Aeo

TurboKoo wrote:
Mon Oct 21, 2019 10:05 am
Aeo wrote:Feels like this is a good maiden effort.
This groupset will really shine after Shimano makes their full switch to 12sp:

  • Servowave brake levers also on mechanical
  • Hyperglide+ cassette and chain
  • viable 1x with 12 gears / 10T low sprocket
  • Direct mount 1x crankset

I imagine they need more space for Servowave, so only in a Di2 lever. Probably possible on the left shifter on a 1x system but that might be too weird.
Servowave also on 800-series mechanical, not on 600-series.
Is that 100%? I have seen conflicting information

ooo
Posts: 894
Joined: Sat May 21, 2016 12:59 pm

by ooo

ST-RX815, ST-R785 - servo-wave levers with extra leverage (di2 only)
ST-RX810, Dura-Ace, Ultegra - servo-wave levers
ST-RX600, 105, Tiagra - non servo-wave levers
'

TurboKoo
Posts: 568
Joined: Wed Oct 29, 2008 7:55 pm

by TurboKoo

ooo wrote:ST-RX815, ST-R785 - servo-wave levers with extra leverage (di2 only)
ST-RX810, Dura-Ace, Ultegra - servo-wave levers
ST-RX600, 105, Tiagra - non servo-wave levers
Only on mechanical versions of Ultegra and DURA ACE have servowave, not on Di2.

Image
https://productinfo.shimano.com/#/spec/ ... c%20brake)
Scott Foil
Shimano 9150
Shimano FCR-9100-P
Shimano C60 tubulars

cunn1n9
Posts: 155
Joined: Sat Jan 15, 2011 1:24 am

by cunn1n9

Is it possible to use the 1x RD with a FD on the grx di2 or does shimano “protect” us by preventing in the firmware? Would like to be able to to run a 52/36 or 50/34 front chainring but (when needed run a 42 tooth cassette out back). This gives enormous range.

Any one tried it?


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ooo
Posts: 894
Joined: Sat May 21, 2016 12:59 pm

by ooo

Use mtb di2 3x11 setup with 48-36-26 crankset (instead of recomended 40-30-22), and change to 1x when needed
'

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TonyM
Posts: 3282
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by TonyM

ooo wrote:
Thu Oct 24, 2019 9:30 am
Use mtb di2 3x11 setup with 48-36-26 crankset (instead of recomended 40-30-22), and change to 1x when needed
but you would have a greater q factor.

ooo
Posts: 894
Joined: Sat May 21, 2016 12:59 pm

by ooo

if he is ok with 167.5 mm q-factor, this option is good (with 48-36 chainrings):
Sram X0 3.3 BB30 carbon cranks with (removable) 104-64 spider (ebay)

Image
'

cycleboyco
Posts: 74
Joined: Sat Jan 30, 2010 1:19 am

by cycleboyco

Finx wrote:
Thu Jun 20, 2019 6:55 am
The chainline changes because they moved the front derailleur out 2.5mm for better tire clearance to the derailleur. You have to use the GRX FD and Crankset together. None of the other components matter. you can mix and match all you want within the Shimano 11 speed family (and within the limits of the individual components).
Looking to get some lower gearing. Currently have Ultegra Di2 set-up with a 50-34 crank (Pioneer dual-sided PM, so can't switch out the chainrings to Absolute black chainrings) and 11-34 cassette and think the RX-810 48-31 will be perfect, keeping most of the top end and providing a few extra gears on the low end. I think the response above confirms this, but wanted to specifically confirm that all I would need to do is swap out the FD and crank so that the chainlines will match-I can still use the Ultegra RX805 RD and Ultegra 8070 shifters I currently have. Thanks.

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markdjr
Posts: 109
Joined: Sun Sep 17, 2017 10:21 pm

by markdjr

cunn1n9 wrote:
Thu Oct 24, 2019 7:06 am
Is it possible to use the 1x RD with a FD on the grx di2 or does shimano “protect” us by preventing in the firmware? Would like to be able to to run a 52/36 or 50/34 front chainring but (when needed run a 42 tooth cassette out back). This gives enormous range.

Any one tried it?


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It works great. Running mine with D/A 9000 di2 Front Derailleur and a way too big cassette. That being said, I bet the 2x version would work with a 42t cassette in most applications.

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