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Discussion Starter · #1 ·
Hi all,

I have a 10 spd Ultegra Di2 rear derailleur (bike from 2012) with a short cage that was originally used for a 11-25 cassette. I replaced it with a 11-28 cassette under the assumption that the short cage would handle the larger cassette.

After installing the new cassette there was a slight noise when in the 28 tooth ring which I unfortunately ignored for too long. The upper jockey wheel bearing finally broke on a climb and bent the short cage slightly in the process.

Now for the questions...

1. Can I repair this without changing the complete derailleur?

2. Can I put a medium cage from a 105 or ultegra groupset on my rear derailleur to provide enough clearance for the 11-28 cassette?

3. Any other thoughts on how I should proceed with fixing the bike?

Thanks in advance.
 

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'brifter' is f'ing stupid
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Hi all,

I have a 10 spd Ultegra Di2 rear derailleur (bike from 2012) with a short cage that was originally used for a 11-25 cassette. I replaced it with a 11-28 cassette under the assumption that the short cage would handle the larger cassette.

After installing the new cassette there was a slight noise when in the 28 tooth ring which I unfortunately ignored for too long. The upper jockey wheel bearing finally broke on a climb and bent the short cage slightly in the process.

Now for the questions...

1. Can I repair this without changing the complete derailleur?

2. Can I put a medium cage from a 105 or ultegra groupset on my rear derailleur to provide enough clearance for the 11-28 cassette?

3. Any other thoughts on how I should proceed with fixing the bike?

Thanks in advance.
1) Yes, you can get replacement cages/pulleys.
2) This will do NOTHING to make your derailleur work better w/ a 28. It should be fine already, you probably didn't adjust the b-tension screw properly.
3) It can be repaired so get the parts and fix it. For future reference, a long cage does absolutely nothing to allow the use of larger cogs. The ONLY thing a longer cage does is wrap more chain. That is it. The newer medium cage road derailleurs have different geometry than the short cage, so the pulleys move at a steeper angle when compared to a short cage.
 

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Discussion Starter · #3 ·
Thanks for the reply. Where can I get replacement cages? I have not seen them on sites such as wiggle etc. Thanks for correcting me on the long vs short cage issue...

Regarding the B-screw, I had it screwed all the way in. Btw, the chainset is a 34-50 compact. Any other adjustment I can then make other than the b-screw?
 

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Discussion Starter · #4 ·
regarding the replacement cage. Can i buy a used Ultegra RD-6700 mechanical rear derailleur and take the cage and pullys from it and install on my Ultegra Di2 RD-6770? Both 10 speed of course.
 

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'brifter' is f'ing stupid
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Any bike shop can order it from Shimano. Might be the same part# as the non-Di2 derailleur, can't remember.

eta:

The cages are not the same. You need the following part #'s which any bike shop should be able to order from Shimano.

6770 Inner pulley cage: Y5XW08000
6770 Outer pulley cage w/ stopper pin: Y5XW98030
6770 Tension & guide pulley set: Y5X998080

In this case I am mistaken and the body for both SS and GS is the same, the only difference is the cage. The upper pulley location is different on the GS cage in relationship to the pivot and this is what provides the clearance for the larger cog.
 

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Discussion Starter · #6 ·
Any bike shop can order it from Shimano. Might be the same part# as the non-Di2 derailleur, can't remember.

eta:

The cages are not the same. You need the following part #'s which any bike shop should be able to order from Shimano.

6770 Inner pulley cage: Y5XW08000
6770 Outer pulley cage w/ stopper pin: Y5XW98030
6770 Tension & guide pulley set: Y5X998080

In this case I am mistaken and the body for both SS and GS is the same, the only difference is the cage. The upper pulley location is different on the GS cage in relationship to the pivot and this is what provides the clearance for the larger cog.
These are the part numbers for the short cage if I am not mistaken? I was unable to find the long cage version on the shimano site. Do you have a link / part numbers to share?
 

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'brifter' is f'ing stupid
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These are the part numbers for the short cage if I am not mistaken? I was unable to find the long cage version on the shimano site. Do you have a link / part numbers to share?
There isn't a GS (medium) cage for the 6770.
 

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Maybe out of left field but I've enjoyed VCRC ceramic pulleys on my road bike or for a more budget option, KCNC pulleys on my XO1 equipped mtb. I feel like the metal pulleys should last longer but I haven't had them on through any really muddy rides yet to see if they disintegrate like the plastic XO1 pulleys did.
 

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Discussion Starter · #13 ·
Thanks for the hint. Just ordered the replacement part from them. Then hopefully I can fix the derailleur and adjust it to fit my 11-28 cassette.

Any hints on possible adjustments? Is it only the b-screw? And also, I have heard that the b-screw should not be screwed all the way in, even to accommodate an 11-28 cassette.
 

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'brifter' is f'ing stupid
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Thanks for the hint. Just ordered the replacement part from them. Then hopefully I can fix the derailleur and adjust it to fit my 11-28 cassette.

Any hints on possible adjustments? Is it only the b-screw? And also, I have heard that the b-screw should not be screwed all the way in, even to accommodate an 11-28 cassette.
I've never seen anything that says to not screw it in all the way. I have seen it cause problems on short hangers or hangers w/ small tabs where the screw reaches an angle where it won't bear on the tab and you lose all the adjustment you made if you go all the way in. In cases like these I've seen B tension screws reversed in the derailleur so the head bears on the tab and that can help. It's hard for me to imagine a hanger that's so short that you can't run a 28 w/ an SS derailleur. This is something that would be very rare...
 

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As CXwrench said, this was an adjustment issue and nothing more. Fix the RD back to stock conditions and adjust the B screw per Shimano's instructions.

I have an Ultegra Di2 system that is running 11-28 on the rear and it has no issue at all, neither does my mechanical Ultegra system that uses 11-28, both RD's are short cages.
 

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Discussion Starter · #16 ·
Thanks guys, looking forward to putting this together once the parts come in. Good to hear that the 11-28 cassette should work. Definitely need the 28t ring for the hills here :)
 
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