Putting Ultegra Medium cage derailleur on DI2 9070

[cunn1n9]

I have a di2 9070 rear derailleur and I also have a mechanical ultegra 6800 rear derailleur with the long GS cage. Is it possible to move the GS cage from the Ultegra into the Dura ace di2 derailleur?

Many thanks


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[coolman2001]

It will work but probably won't work well at all..

[coolman2001]

See this topic:

viewtopic.php?f=3&t=123000

[PinaF8]

I have a di2 9070 rear derailleur and I also have a mechanical ultegra 6800 rear derailleur with the long GS cage. Is it possible to move the GS cage from the Ultegra into the Dura ace di2 derailleur?

Many thanks


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Will not work due to the differences in the stopper screw location.

[pdlpsher1]

I'm using an Ultegra 8050 GS RD. It works great and I really like the new Shimano shadow design. If you plan to run big cassettes you'd be better off with the 8050. I'm using the 8050 along with 9150 shifters and FD.

[naylor343]

Have you tried the derailleur and desired sprocket in its current form without modification? I am sure you probably have, so can ignore my advice. If you have not you should try it first.

A lot of what can and cannot work is governed by the geometry of the derailleur hanger.

Due to geographical location I need very low gears to allow for easy and steady days on the bike. I am on a 2011 TCR adv sl and due to geometry at the rear am able to run a 32 sprocket easily with the b screw adjusted by only a few turns and can even run a 34 sprocket with the b screw almost fully in, including large-large. I obviously do not use large-large but it is possible therefore preventing damage. This is all using a short cage 6870 derailleur.

[MayhemSWE]

I have a di2 9070 rear derailleur and I also have a mechanical ultegra 6800 rear derailleur with the long GS cage. Is it possible to move the GS cage from the Ultegra into the Dura ace di2 derailleur?

Cage can be easily moved but won't do you much good. While the derailleur would be able to take up more chain slack, the angle of the parallellogram remains the same and thus won't be able to clear any larger cassette cogs. In fact I found clearance actually became worse as the upper pulley wheel is located a tiny bit further up on the GS cage.

[cunn1n9]

Interesting and thanks for the help. I have a 30 on my short cage but thought that was the limit as Shimano says 28. I’ll try a 32 and see. Thought the longer cage was the thing but seems like it is not really important.

I have heard of a product by Wolf Tooth called RoadLink that installs onto hanger and drops it down a bit so that might be a better option if needed. Any experience with that?


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[pdlpsher1]

The cage does serve a purpose. Otherwise everyone RD will have a short cage. The cage allows for a higher chain wrap capacity. It takes away the chain slack when you are running a very large cassette. It ensures that any chain slack is removed. If you dare to not give it enough chain length and you accidentally shift into the big-big gear combo, catastrophic result may happen (i.e. your RD and RD hanger are ripped off the frame).

I have used a RoadLink on my tandem which allowed me to use an Ultegra GS RD (6000 series) on a 11-40 cassette. It worked wonderfully. I have since switched to a 8000 GS RD which makes the RoadLink redundant. So I'm using the 8000 GS RD and 11-34 without the RoadLink. The 8000 GS RD also has long enough of a cage to handle the chain wrap capacity of the 11-40 cassette. I'm not an advocate of using the B screw adjustment to make a RD 'work' because I'm afraid of catastrophic frame damage when a shift 'accident' occurs. That's why I'm using the 8050 GS RD. There are some YouTube videos out showing that a 9150 RD can work with a 11-36. I've decided to get the proper equipment for the proper job, and not try to force something to work.

[IrrelevantD]

I have a di2 9070 rear derailleur and I also have a mechanical ultegra 6800 rear derailleur with the long GS cage. Is it possible to move the GS cage from the Ultegra into the Dura ace di2 derailleur?

I can't speak to differences between 9000 series and 6800 series, but I can say that I have successfully swapped cages between a 6870-GS and a 6800-SS and both work fine. Di2 still recognizes it as a 6870-GS, but there are no functional issues on either bike.

Assuming the cages between the 9000 series and 6800 series are the same design it should work. That being said, looking at the EV docs on si.shimano.com, they do appear to be at least slightly different. As both the 6800-SS and the 9000-SS have the same max cog and capacity, I'm going to assume the parallelogram size is the same as is the cage length... but we all know what assumptions are the mother of.

(edit): After reading what @PinaF8 said and the other thread, I'm guessing there's more differences in the derailleur body and mounting between the 9000 and 6800. Looks like a YMMV and AYOR situation.

[Braavos]

CeramicSpeed makes an oversized pulley/jockey cage for all kinds of RD. The stuff is of the top line with performance and price but you always can find the similar things in aftermarket made by Taiwan brands. It will make it happen if I got you right.