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Can I use an 12-30 rear cassette with my current set up

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  • January 2, 2015 at 4:53 pm #22946
    Sensible

    I currently have Ultegra 6700 kit on my bike. I have compact front chainrings 50/34 and a rear cassette 11-28.
    I can’t find any model numbers on the rear deraillier but it is metallic grey on a 2012 bike.

    My chain is in need of replacement and probably need to change the cassette. I have just ordered an Ultegra rear cassette 12-30 and am now having second thoughts as to whether it will fit.

    Having looked at a grey 6700 RD on the net it states the max number of teeth is 33. Now I am not 100% confident about this but if I understand it correctly, 53-34 =16 and 28-11=17, 16+17 =33, which means I am currently on my limits. If I go to a 12-30 then I exceed the number of teeth by one (53-34 =16 and 30-12=18, 16+18 =34)

    HAve any of you used an 12-30 with this set up. Will it work or will I have problems?

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Viewing 7 replies - 16 through 22 (of 22 total)
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  • January 2, 2015 at 11:26 pm #824925
    0
    Sensible

    I have just found the tech
    I have just found the tech spec sheet on the net for the RD-6800. On all counts is has the SS max size sprocket as 28T and total capacity as 33 teeth. That would rule out a 12-30.

    Strangely it shows the GS also having the max size sprocket as 28T but with an overall capacity of 39 teeth.

    It seems that the bigger sprockets may fit but Shimano do not recommend it.

    January 2, 2015 at 10:23 pm #824923
    0
    Stratman

    It would certainly work with
    It would certainly work with a GS

    I’ve an 11-32 with this rear mech

    January 2, 2015 at 10:11 pm #824921
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    LondonDynaslow

    Yes.
    I’ve used 12-30
    Yes.

    I’ve used 12-30 Ultegra cassette with Ultegra short cage RD on a Roubaix and it’s fine. I just have to screw in the B-tension slightly so that the jockey wheels don’t hit the 30t sprocket when it’s on 34×30.

    The proviso is that some bikes will have slightly shorter mech hangers.

    January 2, 2015 at 10:03 pm #824919
    0
    Sensible

    CXR94Di2

    CXR94Di2 wrote:
    https://www.google.co.uk/url?sa=t&source=web&rct=j&ei=JwmnVLbPIMz4UILDgLgL&url=http://si.shimano.com/php/download.php%3Ffile%3Dpdf/ev/EV-RD-5701-3297A.pdf&ved=0CFkQFjAF&usg=AFQjCNGCXruO4Du2Vf7qEpv9fKdks8fJeQ&sig2=XNHfUI5oxsAKakd3xQNyYQ

    This shimano pdf list part numbers. Carefully check, but I would bet that you have a ss rear derailleur.

    That link id for the 105 RD-5700, but I have managed to find the same thing fot an Ultegra RD-6700. Finding the parr number on the rear mech is a different matter though.

    January 2, 2015 at 9:13 pm #824917
    0
    CXR94Di2

    https://www.google.co.uk/url?
    https://www.google.co.uk/url?sa=t&source=web&rct=j&ei=JwmnVLbPIMz4UILDgLgL&url=http://si.shimano.com/php/download.php%3Ffile%3Dpdf/ev/EV-RD-5701-3297A.pdf&ved=0CFkQFjAF&usg=AFQjCNGCXruO4Du2Vf7qEpv9fKdks8fJeQ&sig2=XNHfUI5oxsAKakd3xQNyYQ

    This shimano pdf list part numbers. Carefully check, but I would bet that you have a ss rear derailleur.

    January 2, 2015 at 6:07 pm #824915
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    Sensible

    Not sure if mine is an SS or
    Not sure if mine is an SS or a GS. I suspect it is an SS. Does anyone know the difference in measurement of the cage as I can’t find any model markings on it.

    January 2, 2015 at 5:04 pm #824913
    0
    CXR94Di2

    Change your rd to gs model
    Change your rd to gs model and then you can fit upto 32T.

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