Replace Shimano Dura Ace RD-7900 carbon rear derailleur cage...

[albee]

I am looking to replace the toasted carbon rear derailleur cage on my Shimano RD-7900 derailleur that is in otherwise excellent condition. I was thinking of trying to replace it w/ an aluminum cage from an Ultegra RD-6700. To buy another carbon cage is too cost prohibitive - I would be better off just paying for another slightly used complete derailleur. Does anyone know if the cages are interchangeable?

 

[alfeng]

FWIW. I cannot speak directly to Shimano's latest-and-greatest, but the rear derailleur cages on ALMOST ALL prior Shimano rear derailleurs were interchangeable ...

Here is an Ultegra rear derailleur which I mated with an XT rear cage ...

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You only need to be moderately handy to make the change ...

Allow between 5 minutes AND 5 hours (!?!) ...

You probably don't need to remove the pulley wheels & inner cage, but I do ...

BUT, if you aren't handy OR if you are easily frustrated, then you may not want to undertake the task

 

[albee]

Thanks for this....I'll check into it and see what I can tie together.

 

[albee]

I was checking out trying to find the lowest end road rear derailleur cage that bolts onto the derailleur chassis and I think the lowest I can go is Ultegra, b/c 105's look like the cage is permanently mounted - no allen key hole.

 

[alfeng]

Originally Posted by albee
I was checking out trying to find the lowest end road rear derailleur cage that bolts onto the derailleur chassis and I think the lowest I can go is Ultegra, b/c 105's look like the cage is permanently mounted - no allen key hole.

I do NOT know which Shimano rear derailleurs have a (¿)hidden(?) Allen Key Hole to preclude access to the small bolt which secures the rear pulley cage's pivot shaft ...

Consequently, because it is mostly a cosmetic issue (IMO), if you do not want a long cage (that is, one which appears to be long) AND you can live with a steel cage, then you can possibly opt for the cage from a Shimano ALTUS (RD-M310) rear derailleur which I think has a 13t upper & a 15t (!!!) lower pulley whose cage I presume is secured in the same manner as with most other Shimano rear derailleurs ...

If you are truly handy, then you can re-sculpt the cage to some extent.by removing some of excess material from the steel cages ...

The weight penalty of a steel cage will be small ...

OR, simply get an older generation, USED Shimano rear derailleur whose cage has the general appearance suits which your aesthetic sensibilities ...

 

[albee]

Thanks for the detailed suggested option. The esthetics is relatively irrelevant - function over form is the primary consideration. A short cage bolt-on set of inner & outer plates that match up enough w/ the design of the RD-7900 to do the job is all I need..