Noctilux.95

Currently running mechanical Ultegra 8020 Hydro drivetrain on my Revolt Advanced 0. I would like to upgrade to Di2 and wondering if there is any advantage going with GRX instead of Ultegra? My crank will be an Easton EC90SL with 46-30 with an 11-34 cassette. So it comes down to front and rear derailleurs, and of course, shifters.

Marcus_Ti

A)The Ultegra RD won't have a clutched RD, useful for maintaining chain tension and preventing slap off-pavement.

B) The shifters have very different ergonomics/shapes from the road parts. Whether that is a good thing or bad no one knows--AFAIK there are no in-the-wild reviews/photos yet: https://bike.shimano.com/en-US/produ...t/grx-di2.html

C) FD is made for the new crank spacing...how much it matters IRL, I don't know.

OTOH I doubt the GRX parts will be consumer available for another month at least.

TimothyH

The RD-RX805 is an Ultegra Di2 derailleur with clutch.

https://bike.shimano.com/en-EU/produ...-RX805-GS.html


-Tim-

shoota 

I'd get Ultegra based solely on the fact that GRX is fugly.

tyrion

Just got an email that said GRX will allegedly start shipping in August.

chas58

I don't have any issues with chain on a short cage ultegra. With a long cage - it might be more of an issue.

Koyote

The real question is: why do you want to upgrade to Di2? What is the mechanical groupset lacking that you think you will gain from electronic shifting?

The reason I ask: I have Di2 on a new bike… And aside from the “gee whiz“ factor of electronic shifting, I can’t say that it really works any better than my 105 bike. But it sure did cost a lot more money. .

Wilmingtech

This for sure.

When I travel I rent bikes when I can to try out different bikes and the last 2 times I had Di2 it was ok but there were some minor issues.

One would always drop to the small ring up front when cross chaining which was annoying especially when it was for a very small distance over the top of a hill. I'm sure this can be turned off in the settings and if it was my bike I'd have it dialed in.

I didnt really like the feel of Di2. Granted this was some 1st edition wired Di2 setup and probably a bit used.

That being said, 2 different guys in our group had Di2 issues over the past 6 months that required a visit to the LBS for them. No issues with mechanical for the rest of us.

Would I put Di2 on my bike or buy one with it? Absolutely. Would I spend twice as much as a mechanical group for it? Absolutely not.

I know this isnt anywhere near the answers you were looking for... so back to the topic.

If budget is not an issue and I didnt want to wait I would go with Ultegra including the clutched RD and obviously hydro brakes.

When the GRX group becomes available (if ever) I would then check it out and see if any items were worth swapping out on my bike. I'm curious about the brifters on the new groupset. Your already committed to an Easton Crank so not sure there is a benefit to swapping to a GRX one. And then the derailleur but not sure it will be a better performer than an Ultegra Clutched derailleur.

My 2 cents from the monkey bench.

-Sean

Metieval

he already has that! LOL

TimothyH

It remains to be seen whether GRX Di2 will work with road Di2 components. It isn't a given.

Shimano lists MTB, road and gravel as different series. We know that Di2 components from the MTB and road series can't be used together - it is blocked in software and the system dies.

If Shimano continues this behavior then Di2 from gravel and road series will not function together.

Once the tinkering starts, we may find that running one GRX Di2 component might require that all Di2 components also be GRX just like we are required to run all road or all MTB today.


-Tim-

Marcus_Ti

They do have the GRX parts added to the Di2 compatibility chart now (v3.4.3). Note the asterisk next to RX817 specifying 1X only.

TimothyH

OK. There you have it. It no longer remains to be seen and I withdraw post number 10. Thanks Marcus!

That RD-RX817 is interesting and if you are thinking what I'm thinking, man, I'd like to get my hands on one and try it with a 2x system and 42 tooth cassette.


-Tim-

Metieval

that is crazy, on Shimano's part.

MTB RD coupled with di2 road levers would be a SRAM killer. for 1x gravel builds

Marcus_Ti

Great minds, mi amigo

TimothyH

The asterisk on the compatibility chart is like an invitation.


-Tim-

Bryan C. 

I haven't tried this personally but I do know the S-Works Diverge uses DA road Di2 levers with an XTR derailleur.

I almost bought a lower end Diverge and swapped in something similar with Ultegra and XT components. Both shops I was dealing with didn't see this as a problem.

???

https://www.specialized.com/us/en/me...=239529-154308

Metaluna

I could be wrong, but I believe the rule is that Di2 shifters will work with anything, but what you can't do is mix MTB and Road derailleurs, e.g. a road FD and mountain RD won't work together in the same network. But if you swapped in a mountain FD, the road shifters would then work fine (I'm not sure how well the mountain FDs work with road cranksets though). Since a 1x drivetrain has no FD, that apparently satisfies the no-mixing rule.

redlude97

Does the current Di2 RX RD not work with a 42T? I'm running the mechanical RX RD with a 50/34 11-40 2x setup with some room to spare still

Bryan C. 

Ok, I heard the same thing about mixing derailers too. 1x with Di2 would be a nice set up depending on the cassette.

I'm still on the fence about the 1x on my Diverge. Cassette is too gappy, I may just swap in a 2x system. I'm looking into the GRX Di2 kit to see if I want to go that way.

Marcus_Ti

A $320USD invitation. 15% more expensive than the RX805 it supersedes. Ooof. Would royally suck to spend the money only to have it be firmware blocked from working. Product pics it looks like the RX815 and RX817 use different idler pulleys--RX817 uses a tooth-ier pulley unlike the rest of their "road" products.

Metieval

good to know!

MY 90's hybrid flat bar is set up with XT saint and XT 11-36 10s. with a wolftooth 130 bcd 42T chainring.

it is super smooth! as in it makes SRAM 1x stuff not very desirable at all.

Thus for a Gravel bike 1x, and to stay with Shimano. then Di2 is where it is at but only by mixing MTB RD with Road levers.

blazin

I can confirm this is accurate. I run DA shifters 1x with XTR RD. Works like a dream.

TimothyH

@blazin and @Bryan C., thank you.

I stand corrected and educated.


-Tim-

blazin

Here's an outdated but still useful article on Gravel Cyclist about Di2 compatibility issues:

https://gravelcyclist.com/bicycle-te...road-shifters/

Two years ago, the inability to mix MTB RD with road FD was a missed opportunity. With only compact cranks available and most road RDs limited to 32 or 34 cassettes max, there were few if any ways to assemble a 2x, Di2 system with gearing below 1:1.

Today, with the availability of the RX and now GRX groups, as well as the growing number of "adventure" sub-compact chainrings/cranksets, you should be able to put together a 2x drivetrain with a below 1:1 low-end pretty easily.

Interestingly, SRAM etap AXS also makes this mistake. The road cassettes top out at 33 and the Eagle RD cannot be run with the road FD. You'd think they would have learned. (Not to mention that the road FD's battery eats into tire clearance.)

I believe that electronic shifting is a great solution for gravel riding. No more worrying about gunking up shift cables. It just works. In all conditions. I've submerged my Di2 RD, run it through mud, had it coated in ice and it's handled it all. But, thus far, component makers haven't really understood the unique requirements for gravel drivetrains. Hopefully, GRX Di2 will be a step in the right direction.

Koyote

FYI: That is just a shift mode called Synchro. A couple button pushes (on a junction box) will switch it to semi-synchro or the full manual control. I prefer full manual.