# Will Dura Ace 11-28 work with 7800?



## mtaylor495

I'm getting a compact R-700 and want an extra gear in the back for some mountain rides. Will the 7900 series 11-28 work with my 7800 shifters/der.? I think I've read somewhere that it only works with 7900 series.

What is my other option for a larger cassette. I know IRD makes some huge cassetts, but I think I would have to switch the rear der to a long cage.


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## coasterbrake

No the 7800 derailleur doesn't have the capacity to run a 28.


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## loubnc

Here's another option:

I ran a DA7800 rear with a 11-27 cassette all last year with the R700 without any issues. Just some minor adjustments to the B-screw to clear everything. 

I basically made the cassette out of an Ultegra 12-27 by removing the 16T and adding an 11T and lockring. This makes an 11-12-13-14-15-17-19-21-24-27 cassette. The 11T and lockring were purchased from bikeparts.com.


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## mtaylor495

That's interesting. I might give that a try.


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## Corndog

The 28 will work just fine with a 7800 short cage. Shimano is very conservative with it's wrap capacity specs. You can actually get a 30T on there with out issues.


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## joeveg

I was also interested in running a DA 11-27 cassette with a 7800 DA rear der. However, I've found this statement attached to the DA 7900 cassettes on the mail order web sites:

"The 7900 cassette is compatible with the 7800 rear derailleur and chain, however, the 11-27 and 11-28 require the 7900 rear derailleur."

Is this correct about the 7900 11-27? 
I can understand why the 11-28 won't work, but I've read about several people here that run a custom made shimano 11-27 7800 cassette without problems. Why would a 7900 11-27 be any different?

Also, has anyone had any luck with a SRAM 11-26 with a DA 7800 rear der?

Thanks.


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## cpark

This compatibility chart might help.

http://www.cycleslambert.com/download.php/?folder=Documents&file=DURAACE7900.pdf


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## Corndog

Both the 11-27 and the 11-28 will work just fine with the 7800.


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## j-dogg

Here is the next question, where did you get a 28-11 Dura-Ace (or is it an XTR?)

Biggest DA range with 11t I saw was a 25-11 I think.


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## coasterbrake

Shimano makes a dura-ace 7900 cassette in 11-28 now.


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## maytown roadie

*7900 shimano*

I have all 7800 D.A. on my bike, just got 7900 chain and 7900 11-28 cass. everything
works fine, I have a short cage R.D..


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## HikenBike

Corndog said:


> Both the 11-27 and the 11-28 will work just fine with the 7800.


FWIW, I have a 12-27 Ultegra cassette with the 7800 group; no problems.


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## shaochieh

I got Ultegra SL with 7900 11-28 cass and using short cage R.D also. Everything seems to work all right so far.


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## rook

It works fine. Tried it on a friend's bike and his 53x28 worked fine. I agree with Corndog who said that Shimano is very conservative with their cog/derailler max capacity specs.


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## tombike

*With compact?*

To those who have used the 11-28 7900 with the short 7800 RD: Was this with a compact crankset (50-34)?


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## HikenBike

tombike said:


> To those who have used the 11-28 7900 with the short 7800 RD: Was this with a compact crankset (50-34)?


Yes. I recently replaced my 11-27 with a 11-28 with a compact crank (50/34). No problems with my 7800 group. I hope this helps.


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