Shimano 12s GRX RX820/RX822/RX610, cable pull actuation ratio 11s/12s compatibility

[robertbb]

Am I the only one that is disapointed that the 12-speed GRX is mechanical only?
Now I consider Ultegra Di2 for my new gravel bike instead of GRX.

Patience, child. Patience!


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We all know GRX Di2 is coming. The question is how patient we need to be

On the basis that we're just entering into Spring/Summer over here, and GRX Di2 is likely to cost a pretty penny when it eventually drops (even if it's imminent), I opted for 105 Di2 for all-road and light gravel duties for the next 12 months.

Anyway. GRX 12 mechanical is good in the sense that the cranks havn't changed. 11 speed groupsets tend to work nicer with 12 speed chains, so the ability to whack a new Shimano narrow/wide (now available in 38t) makes for a good improvement to existing 11 speed GRX builds. Very strange that there is no 165mm option in the 820 series though.

No HG cassette is the biggest bummer of all. I know it's not just me banging on about this. Seen similar sentiment on countless forums, youtube reviewers, youtube comments. Big opportunity missed here.

[DawnBat]

Sram is too tricky, before shimano released the new groupset, they filled the market by a expensive xplr 1231 cs.

[satanas]

So who's going to try the mid cage derailleur with that 11-44 ingrid and 2x 50-34?

If it was me, I'd try either:

1. The RX820 2x RD, or
2. The R8120 MTB 2x RD with a Wolftooth Tanpan, or
3. To fit the 8120 cage on the RX820 RD if the stock cage didn't work. (NB: I haven't seen the RX820 exploded diagrams yet so have no idea if this is possible.)

I have a Sunshine 11-42 12 speed to test once the stuff reaches Australia - maybe by 2025 or so? - and would be using somewhat smaller than 50x34 rings too, say 44x28 (available from TA for RX800).

[Omiar]

...

I don't know where you got your prices but I think you are comparing MSRP to sale price. Disappointing "rework" until we get di2, but it can't be more expensive than di2 ultegra

These are the public prices in Germany with some GRX 12spd parts already available. Availabilty has been decreasing with every minute of course with much of the popular parts being sold out quickly. I doubt the prices will drop any time soon.

1x12 full groupset, available to order
https://www.bike-discount.de/en/detail/ ... cle/259627

Individual 12spd parts https://www.bike-discount.de/en/brand/s ... 8&f=235893

Second source for pricing
https://www.bike24.com/search-result?se ... price_desc

To compare shifters + brakes

724.90 EUR for Shimano GRX ST-RX820+BR-RX820 2x12-speed Disc Brake Set
https://www.bike-discount.de/en/detail/ ... cle/256442

669.00 EUR Shimano ULTEGRA Di2 ST-R8170+BR-R8170 2x12-speed Disc Brake Set
https://www.bike-discount.de/en/shimano ... rake-set-2

449.00 EUR for Shimano 105 Di2 ST-R7170+BR-R7170 2x12-speed Disc Brake Set
https://www.bike-discount.de/en/shimano ... -brake-set

[CampagYOLO]

No HG cassette is the biggest bummer of all. I know it's not just me banging on about this. Seen similar sentiment on countless forums, youtube reviewers, youtube comments. Big opportunity missed here.

Garbaruk offer a 11-52 HG 12 speed cassette. That should work with new GRX and also would save some weight.

[DawnBat]

So who's going to try the mid cage derailleur with that 11-44 ingrid and 2x 50-34?

If it was me, I'd try either:

1. The RX820 2x RD, or
2. The R8120 MTB 2x RD with a Wolftooth Tanpan, or
3. To fit the 8120 cage on the RX820 RD if the stock cage didn't work. (NB: I haven't seen the RX820 exploded diagrams yet so have no idea if this is possible.)

I have a Sunshine 11-42 12 speed to test once the stuff reaches Australia - maybe by 2025 or so? - and would be using somewhat smaller than 50x34 rings too, say 44x28 (available from TA for RX800).

And the rx812 RD with m8000 sgs cage mod, it can take on 46t CS maxmium, maybe new 12s STI and old 11s RD is compatible.
RX822 sgs and gs is nearly the same as m8100 sgs and gs, but is different from m8120, and m8120 has the longest cage of all 3 m8100 RD.
Pull ratio is really annoyed.

[pdlpsher1]

There’s no doubt that a non-Shimano cassette would shift worse than a genuine Shimano cassette.


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[CampagYOLO]

There’s no doubt that a non-Shimano cassette would shift worse than a genuine Shimano cassette.


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Agreed. However, for some wheelsets Microspline isn't an option.

[ooo]

Will the GRX 12-speed rear derailleur work with a Shimano 12-speed mountain bike shifter?

Sorry, but the answer to that is a hard no. When we were setting up this drivetrain, I happened to have an XT shifter freshly pulled from another bike, so we tried it before hooking up the GRX levers. It took all of five shifts to realize that the pull ratio was off.

[Kubackjeee]

NGL they are out of their mind with those prices for a mechanical groupset (which I actually prefer). At least we gonna get even better prices for slightly used 11s components

[satanas]

There’s no doubt that a non-Shimano cassette would shift worse than a genuine Shimano cassette.

True, but reports online suggest those Garbaruk cassettes shift okay.

Unfortunately Shimano haven't seen fit to offer a wider range 2x HG cassette either. 11-36 is IMHO too small and with some nasty gaps, and 10-45 would be even worse on the road, though okay for MTB use. JOM at gravelcyclist.com apparently asked at the launch why there wasn't something like an 11-40 option, and IIRC the answer was that they ran out of time and resources so maybe there might be something later, but recent Shimano behaviour - like the cancelled 11-28 Dura-Ace 9200 cassette - suggests not.

This RD...

https://www.somafabshop.com/shop/590839 ... rear#attr=

...might be a good option for very wide range 2x, assuming that Shimano haven't changed the pull ratio between 11 & 12 speeds. Rumour has it things are the same for their MTB 10, 11 & 12 so fingers crossed...

[robertbb]

I think the 11-36 ratio from Shimano is actually great.

11-12-13-14-15-17-19-21-24-28-32-36

The Campagnolo 12 speed cassettes (ending in over 30t) both have a horrible 19-22 jump:

11-12-13-14-15-16-17-19-22-25-28-32 T
11-12-13-14-15-16-17-19-22-25-29-34 T

I'd rather forgo the 16t in favour of the Shimano progression, that's for sure. I had a Potenza 11 cassette back in the day that had the same 19-22 and didn't really pay attention to the progressions. When I started riding it I noticed one particular jump just pissed me the f*ck off and when I investigated that was the one.

I'm yet to ride my new 105 Di2 setup because I'm waiting on some final bits and bobs to get the build and bleed done, so havn't ridden the 11-36 yet but I have high expectations.

One thing Shimano could have done is just add a 36t to the top of their 11 speed 11-32 cassette:

11-12-13-14-16-18-20-22-25-28-32-36 T

This would have been pretty sweet.

[pdlpsher1]

It really depends on your local gravel terrain. The HG700 11-36 would be horrible for the terrain that I ride on. The gradient here is always changing very fast. I don’t want a cassette with only a one tooth jump. The two tooth gaps on the HG800 11-34 are even too small. For my terrain the 11-speed 11-40 cassette is perfect. It has big gaps and they minimize the number of shifts when dealing with fast changing gradients. If I lived in a different part of the country then I might prefer a cassette with smaller gaps.


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[satanas]

^ The 11-40 is okay for more mountain bikey things but IME it's a PITA if you're on a flat road with crosswinds. I found myself frequently switching between 21 & 24T - too high or too low; the 11-34x11 is way better in this situation, and the 11-36 12 speed would be even worse.

My preference would have been something like...

11,12,13,15,17,19,21,23,25,28,32,37

...as this would have closed the annoying 11-13 gap and given a bit more range. That plus the Ingrid 44T11 would handle just about everything (with 2x). Sigh.

[DawnBat]

duplicate, plz delete this one. sorry.