7900 dura ace rear mech

Discuss light weight issues concerning road bikes & parts.
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by mec287

Hi, I was reading a recent review of dura ace 9000 which said 'and the rear mech can now take a 28T rear cassette'. I have a 2012 S-Works Tarmac SL4 with dura ace 7900 throughout and am hoping to swap out my stock 12T-25T dura ace cassette for an 11-28T one (i'm going to the alps later in the year). Can anyone shed any light on whether this will work OK?
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by HillRPete

Yes, the RD-7900 is spec'd for 28t max, there's also a cassette to go with.

(Personally I'm using the 7900 with the 11-28 SRAM Red cassette)

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by eric

Shimano's spec is conservative, both for max cog size and for chain wrap. I've gotten a 7900 to handle a 30t cog. How far you can go depends on the geometry of your frame's derailleur hanger.

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