# 12-30 cassette question.



## Phatz85 (Sep 19, 2011)

Hello, I'm riding a 2011z85 and I'm planning on doing a very hilly century ride 9000 feet of climb with grades of 23%. I would like to switch out the 11-28 for a 12-30 cassette but was told the "stock" rear derIlieur wouldn't accommodate the 30 cassete. Does anyone know what rear deraileur I will need and do I have to adjust it every time I switch cassettes. Thanks for your help.


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## fun2none (Mar 16, 2010)

I would move this post to the "Components, Wrenching" forum for best advice.

The manufacturer's specifications for your rear derailleur (assuming it's an RD5700) state a maximum cog size of 28T. In practice, you can get away with the 12-30 cassette. Two extra teeth won't matter. The correct derailleur is the RD5700A, which is rated for 30T max cog. If you use a 9-sp mountain bike derailleur and longer chain, you can use an 11-32 cassette which should get you up any hill. See the picture below.










If you do install the 12-30 with your stock derailleur and chain, DO NOT to use the large-large gear (50-30) combination.


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## z85guy (Apr 25, 2011)

I have the 5700a RD and switched back to the 11-28 from the 12-30 with no problems.


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## .je (Aug 25, 2012)

This bike, as an example, comes with a 12-30t cassette on the same 5700 RD, from the factory.
http://www.diamondback.com/podium-3-pavement-road-endurance-road


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