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New Bike - Upgrading ChainRings (Techie Advise Needed)

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  • 08-05-2021 6:45pm
    #1
    TontoMurphy
    Registered Users Posts: 187 ✭✭


    Hi guys,

    Built up new bike from components onto a new frame.. The Ultegra crank that came with the groupset is a 50/34, too small for me. Want to upgrade to a 52/39 so am looking at just changing the chain rings - easiest option.

    Bike will be running Di2, so i can tell it i'm on a 52/39 to recalibrate shifting and gearing...

    I know that there are "suggested pairings" for chain rings; MA, MB, MD based on ring sizes. 53/39 being MD, 52/36 being MB. See link below.

    https://www.bike24.com/p293274.html

    Question is, can i run a 52/39. i.e. mixing the MD and MB rings. Bolt circle seems same. I don't "think" there would be an issue, just don't want to shell out and find they won't work.

    Cheers guys.


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    #2
    Daroxtar
    Registered Users Posts: 4,328 ✭✭✭Daroxtar


    Yes you can. Shimano reccomend 16 teeth or less of a difference between big and small chain rings so 52-39 is fine


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    #3
    TontoMurphy
    Registered Users Posts: 187 ✭✭TontoMurphy


    Thanks Daroxtar..

    No issue with the MD/MB carry on?


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    #4
    Tony04
    Registered Users Posts: 646 ✭✭✭Tony04


    Shouldnt be distance between chainrings are same so shifting isnt affected if anything better because there is less of a jump


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    #5
    Paul Kiernan
    Registered Users Posts: 2,161 ✭✭✭Paul Kiernan


    First dibs on your 50/34 rings if you're selling them ;)


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    #6
    TontoMurphy
    Registered Users Posts: 187 ✭✭TontoMurphy


    Paul Kiernan wrote: »
    First dibs on your 50/34 rings if you're selling them ;)

    Yep, you're first in line... Soon as i get them installed i'll let you know


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    #7
    Tony04
    Registered Users Posts: 646 ✭✭✭Tony04


    First dibs if youre selling your old frame and its a 56cm ;)
    Also would love to see pictures of your build


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