Shimano R8000 RD question

Triathlon Forum
1

Working on a bike build and just installed the shimano low profile ultegra RD, the R8000. In the past, I was more used to ‘traditional’ RDs, like the ultegra 6800 series.

So my question: the new RD-R8000 apparently (?) has no spring on the mounting screw or on the pivot adjoining to the mounting screw. But older RDs like the 6800 had two methods for maintaining spring tension: the spring on the mounting screw and the twisting action of the pulley cage. But the new R8000 RD has only one way of maintaining spring tension: the twisting action of the pulley cage.

Anybody have feedback as to how well these new RDs take up chain slack as you shift through your cassette and chainrings? The bike is not complete, so I have not tested it, but it sure seems like this is a step backward. But maybe I am wrong about this?

2

Exact one on my road bike. No issues. Never noticed any difference to other things I’ve used.

3

They are great.

4

Do they shift and maintain chain tension better than dual spring RDs ?

5

I have built at least 200 bikes with R8000 rear derailleurs and have never had a single problem.

6

Are they supposed to have a spring on the fixing bolt?

7

No.

8

I have put several seasons of cyclocross into the Shadow series derailleurs with zero problems. Chain retention is excellent.

9

Good to know.

This will be for a gravel application. What size chainrings are you running on that bike? What size cassette?

10

I’ve done R7000’s, R8000’s, M8000’s and M9000’s. They are all basically mechanically the same, all having that extra link.

They are so much better than the 5800, 6800 series derailleurs

11

This will be for a gravel application. What size chainrings are you running on that bike? What size cassette?

I have run the Ultegra DI2 (both with clutch and without) and currently run GRX DI2 shadow series on my gravel bike, again with minimal issues. I’m currently running 50/34 x 11/36 on that bike. CX bikes have been all over the map; Ultegra mechanical, UI2, DA mechanical, 2x, 1x, different chainring and cassette combinations. Suffice to say I’ve put the design through a significant ringer.

12

I was looking at my new partially-finished build the other day and was sure I had made a mistake. Thanks for the question.

Are you using direct mount?

13

I’ve done R7000’s, R8000’s, M8000’s and M9000’s. They are all basically mechanically the same, all having that extra link.

They are so much better than the 5800, 6800 series derailleurs
What exactly makes them better than 5800 or 6800 series RDs? I would think that the lack of that spring on the fixing bolt makes it harder for the R8000 RDs to take up chain slack?

14

No, using a conventional dropout on a thru axle gravel frame.

15

I really don’t know, they shift so much better that when I work on a bike with the older series derailleurs I nearly always replace it.

It might be that having the pivot point further back allows the chain to align better with each cog. Just spit-balling there.

16

Thanks for the input.

One more question, are the RD-R8000 and the RD-6800 fully interchangeable in terms of their cable pull with either ST-R8000 or ST-6800 shifters?

17

Yes.

18

Thanks for the input.

One more question, are the RD-R8000 and the RD-6800 fully interchangeable in terms of their cable pull with either ST-R8000 or ST-6800 shifters?

Yes, they are, even with the 5800 and R7000