# Ultegra long cage on dura ace 9070 di2 rear deraileur?



## SwiftSolo (Jun 7, 2008)

Getting old but my passion for long steep climbs remains. I currently have new dura ace di2 (hydro disc) 9070 rear deraileur which has a 28 tooth limit. Can I simply change the cage to a new long cage ultegra di2 (32 tooth limit) of do I need to change the entire deraileur?


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## rowcache (Jul 7, 2014)

SwiftSolo said:


> Getting old but my passion for long steep climbs remains. I currently have new dura ace di2 (hydro disc) 9070 rear deraileur which has a 28 tooth limit. Can I simply change the cage to a new long cage ultegra di2 (32 tooth limit) of do I need to change the entire deraileur?



I think you should be able to just change the cage, see this link. The answer is a few questions down.

Technical FAQ: Flying with Di2, combining components, and more - VeloNews.com


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## MMsRepBike (Apr 1, 2014)

A longer cage won't make you able to get to any bigger cogs. It'll just wrap more chain, like if you had a triple and needed that done. The correct way to do this is to get a 6870 gs rear derailleur. 

What will help you is a long or "properly" shaped rear derailleur hanger which is out of your control, that's up to the frame manufacturer. You may get lucky. Some frames can run big cogs easy and some simply cannot without the correct geometry derailleur.


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## cxwrench (Nov 9, 2004)

MMsRepBike said:


> A longer cage won't make you able to get to any bigger cogs. It'll just wrap more chain, like if you had a triple and needed that done. The correct way to do this is to get a 6870 gs rear derailleur.
> 
> What will help you is a long or "properly" shaped rear derailleur hanger which is out of your control, that's up to the frame manufacturer. You may get lucky. Some frames can run big cogs easy and some simply cannot without the correct geometry derailleur.


While this is typically the case, I think w/ the 6800 stuff the body of the derailleur is the same, and the upper pulley is offset w/ the longer GS cage. This is how K-Edge make it work w/ their Ki-2 conversion pulley cage. I need to take a look at one when I get to work, but pretty sure that's the case w/ new Ultegra. 
I seem to remember trying the Ultegra/Dura Ace cage swap at some point and I don't think it worked but I could be wrong.


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## SwiftSolo (Jun 7, 2008)

I look forward to hearing what you find. I appreciate the help.


cxwrench said:


> While this is typically the case, I think w/ the 6800 stuff the body of the derailleur is the same, and the upper pulley is offset w/ the longer GS cage. This is how K-Edge make it work w/ their Ki-2 conversion pulley cage. I need to take a look at one when I get to work, but pretty sure that's the case w/ new Ultegra.
> I seem to remember trying the Ultegra/Dura Ace cage swap at some point and I don't think it worked but I could be wrong.


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## MMsRepBike (Apr 1, 2014)

cxwrench said:


> While this is typically the case, I think w/ the 6800 stuff the body of the derailleur is the same, and the upper pulley is offset w/ the longer GS cage. This is how K-Edge make it work w/ their Ki-2 conversion pulley cage. I need to take a look at one when I get to work, but pretty sure that's the case w/ new Ultegra.
> I seem to remember trying the Ultegra/Dura Ace cage swap at some point and I don't think it worked but I could be wrong.


The RD-6700-SS and RD-6700-GS are identical except for the cage length. so yes, it's possible to put a GS cage on a RD-6700-SS. What this will do is give you the ability to wrap a longer chain. 


It will not give you a bigger max cog size. Both RD-6700-SS and RD-6700-GS are rated to a 30 T max cog size. The difference is the total capacity, because the GS version was intended for use with the road triple crank that was offered in the 6700 series Ultegra group.

The above is standard for most all older groups, but like I said before, things have changed:


The RD-6800 and RD-6870 series depart from the tradition of using identical bodies with the cage length being the only difference. The slant angles of the parallelograms are different, and the dimensions of the P knuckles are different.


These dimensional differences are tailored to match the slope of 11 speed tight-ratio cassettes vs wide-ratio cassettes. This was done due to the industry shift away from road triples + 11-28 to compact cranks + 11-32


RD-6800-GS moves the top jockey pulley along a steeper slope because it's designed to be used with an 11-32. 
RD-6800-SS moves the top jockey pulley along a shallower slope, to match an 11-28 or smaller max cog.
The Di2 versions, RD-6870-SS and RD-6870-GS, follow this same design.

So basically my first comment is correct here and the OP should follow my advice.


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## cxwrench (Nov 9, 2004)

Yep, looks like you're right this time.


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## SwiftSolo (Jun 7, 2008)

Thanks to both of you guys. 

I think the answer may be to lose another 10 lbs and stick with the 28. 

I may try my campy 11 speed 29 tooth cogset from my sl3 just to see if it works (it's a non disc 303 wheel so I can't actually ride it but I could likely change the freehub on my Enve's to campy if it shifts right).


cxwrench said:


> Yep, looks like you're right this time.


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## spdntrxi (Jul 25, 2013)

how about SRAM XG-1190 11-30 Cassette.. would that cassette work


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## slowdave (Nov 29, 2005)

Quick thread hijack, I think I have bent the cage on my 9070 rear mech, both hangers I have seem to have jockey wheels slightly out. And in the 25 the mech goes in then after 10-15 seconds drops back to the 23. With no diagnostic box at lbs, I think cage has been bent am I able to replace just the cage? And if so what do I need, no need for gears greater than 28, no wind is that strong on the gippsland plains
Again sorry for the hijack


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## SwiftSolo (Jun 7, 2008)

That may be worth a try. Now that I think about it my sl3 wheel is 130 and I think my hi-mod disc is 135 so it would not work even to try the shifting.


spdntrxi said:


> how about SRAM XG-1190 11-30 Cassette.. would that cassette work


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## CliffordK (Jun 6, 2014)

Here is a good page on Derailleurs.
Park Tool Co. » ParkTool Blog » Rear Derailleur Overhaul

You're probably fine with either the medium or long cage for a 25/28T cassette, and not too radical of chain rings.

I think the cage should be absolutely parallel to the axis of the tire. You should be able to check it with a straight edge... somehow. 

Mine was angled more or less parallel to the spokes on my old rear wheel, and worked fine for years. Then when I changed to a rear wheel with more dishing, I can't get to the last cog without throwing the derailleur into the spokes. It turns out that I think I bent my derailleur hanger 30 years ago. Anyway, notes indicate that one can make a jig to both test that the hanger is parallel to the rim, as well as straightening it, but you could probably verify that it is not bent with a straight edge and tape.

Here is a great page about home checking and straightening a derailleur hanger. Other pages on the web might suggest using the official Park tool.

I am a little suspicious about your setup that seems to be shifting properly, then drops back after a few seconds. I suppose it never hurts to first check the cage and derailleur hanger. But, it sounds like either a derailleur adjustment problem, or perhaps something failing with the derailleur or shifter levers.


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## rcb78 (Jun 15, 2008)

I've actually tried this for a customer that insisted I at least try for him,, his money. The pulleys ARE offset on the cage like the K-edge version, but not as much, AND the body is different too. So depending on how close you are currently, it may or may not be enough to make it work. Some hangers hold the derailleur out further than others. YMMV


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