Di2 RD Setup Issues

[RobJ]

I am having setup issues with my Di2 RD and looking to see if anyone has any tips or ideas. I haven't seen this before in other setups and running out of ideas, other than slogging down to the LBS.

It's a GRX 817 Di2 RD with the long cage for 11-42. Cassette is the Shimano 11-42. It's on my new Zank, so the hanger and frame are straight. RD is new too.

The issue is that the RD won't shift up into the two largest cogs and is overshifting past the smallest. I've setup the B-adjustment and while Di2 has low/high limit screws, they function differently than on mechanical RD's. But I futzed with them too. I tried some of the info in the Shimano Dealer's Manual too. When the shifters reach the 3rd largest cog, there aren't even any "clicks" left on the shifter. So it's not even trying to throw the chain up to the next cog. Similarly at the high end (smallest) there are "clicks" left that throw the chain past the last cog. It's almost as if the RD doesn't know the physical position of the 11 cogs. I was looking for a way to position the chain on a certain cog and tell the RD/shifters/software that that's where they are etc.. Hopefully that makes sense? Picture below is just for reference viisually of the setup. Any thoughts?

https://i.imgur.com/IA8YGgcl.jpg

[loxx0050]

Read this article. I think this might be your issue.

https://wheelsmfg.com/blog/standard-mount-vs-direct-mount-derailleur-hangers.html

[RobJ]

Read this article. I think this might be your issue.

https://wheelsmfg.com/blog/standard-mount-vs-direct-mount-derailleur-hangers.html


Thanks! That sounds like it. Because I thought the hanger looked different. It’s a direct mount it appears. And the RD has the extra pivot point (B-Link) which I didn’t understand too. Going to remove that link and try the setup etc.


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[RobJ]

WOOOHOO!!!

That was exactly it. Removed the B-Link pivot from the RD. Adjusted the B-screw and perfect shifting. Learned something new about the new RD hangers. This place rocks!

Thanks loxx0050 for the quick response!

[echappist]

I'm a bit late, but I had that exact problem and actually started a thread about it a few weeks ago (https://forums.thepaceline.net/showthread.php?t=254155).

Removal of the extension, which Shimano calls the "Axle Bracket" is what is needed on frames with direct mount hangers.

It was only after I had the issue that I understood the context of "direct mount", as my older 6870 GS RD also directly mounts to a "regular" hanger but does not need the axle bracket (whereas my 8050 GS RD would need the bracket on the same "regular" hanger)

[loxx0050]

I'm a bit late, but I had that exact problem and actually started a thread about it a few weeks ago (https://forums.thepaceline.net/showthread.php?t=254155).

Removal of the extension, which Shimano calls the "Axle Bracket" is what is needed on frames with direct mount hangers.

It was only after I had the issue that I understood the context of "direct mount", as my older 6870 GS RD also directly mounts to a "regular" hanger but does not need the axle bracket (whereas my 8050 GS RD would need the bracket on the same "regular" hanger)



Thanks to this guy is where it should be directed. I recall reading this thread and noticed it seemed like a similar issue.

[RobJ]

I'm a bit late, but I had that exact problem and actually started a thread about it a few weeks ago (https://forums.thepaceline.net/showthread.php?t=254155).

Removal of the extension, which Shimano calls the "Axle Bracket" is what is needed on frames with direct mount hangers.

It was only after I had the issue that I understood the context of "direct mount", as my older 6870 GS RD also directly mounts to a "regular" hanger but does not need the axle bracket (whereas my 8050 GS RD would need the bracket on the same "regular" hanger)


Wish I would have seen your thread. Like you could have saved me a few hours ;-). But looks like you were the contributor to the one who responded to my post, so grazie.


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[echappist]

Both of you are too kind; glad to help, but @loxx0050 is the one who gave the OP tangible help.


I just really wish all this stuff were made more clear. I think this was noted in the link @loxx0050 provided, but apparently Sram derailleurs are still "traditional", whereas Shimano has the axle bracket for the newer stuff at the 105 level and above (that is to say, 7000-, 8000-, 9100-, and GRX series derailleurs)


Also another fun tidbit, the axle bracket for mechanical RDs are not considered to be compatible with those on the Di2 RDs. All these standards are quite something for the home mechanic to keep up.