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Post mount disc calipers

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  • January 26, 2017 at 2:05 pm #26713
    fullers1979

    Having just bought a Cannondale Caad12 disc frame I now need a post mount front caliper. Up until a week ago the Shimano rs785’s were in plentiful supply but they have seemingly all disappeared! 

    Then I got to thinking…..as the rs785 are apparently just rebadged XT’s why couldn’t I use another MTB caliper from Shimano? Having never ridden a MTB to any kind of standard I have no clue when it comes to any compatibility issues. Most of them are described as being post mount but equally they suggest 160mm rotors or above. Are some going to be too powerful for a road bike? Has anyone got any successful recommendations? 

    Please help!!!!!! 

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  • January 27, 2017 at 6:47 am #885861
    0
    TypeVertigo

    I remember BikeRadar also had

    I remember BikeRadar also had coverage of the 2016 Bespoked bike show where one of the custom builders, Rusby Cycles, paired a Deore XT M785 caliper with R(S)785 STI levers.

    Check out images 32-36 on this gallery.

    http://www.bikeradar.com/news/article/bespoked-ukhbs-2016-gallery-46819/

    January 26, 2017 at 4:33 pm #885859
    0
    fullers1979

    I’m not overly fussed by

    I’m not overly fussed by 160mm rotors as at 6’4″ and 85kg I’m not small!! 

    I’m now having to work out whether my OCD can cope with a different caliper on the front compared to the back! Front is post mount but rear is flat mount. So either different calipers or an adapter on the back. Hmm…….

    January 26, 2017 at 4:24 pm #885857
    0
    tom_w

    One of the local bike shops

    One of the local bike shops round here used to regularly match XTR calipers to DI2 hydraulic levers for a (very slightly) lighter weight set up.  

    However, whilst they are compatible, the rs785 calipers don’t have a banjo anymore, where as I think XT calipers still do.  No real functional difference, it just gets you a tiny bit more heel clearance  apparently.

    January 26, 2017 at 3:45 pm #885855
    0
    SingleSpeed

    All calipers are designed

    “All calipers are designed around 140mm discs”

    Nope that bit is wrong…Post mount with no adapter is 160mm

    The 140mm is a Roadie thing (and very very old MTB)

    January 26, 2017 at 3:39 pm #885853
    0
    part_robot

    I have a used one if you want

    I have a used one if you want to buy it off me đŸ™‚

    Good bike shops can get hold of them (new design but still post mount) though.

    January 26, 2017 at 2:58 pm #885851
    0
    kev-s

    Yep as above pretty much any

    Yep as above pretty much any shimano caliper can be used as long as your hose connection matches the connection on the caliper, even then if it dosent its just a case of buying the correct fitting hose

     

    I used to run xt calipers on my road bike before changing to a frame that has flat mounts, all calipers are designed around 140mm discs and then use adaptors to fit bigger discs

    January 26, 2017 at 2:42 pm #885849
    0
    TypeVertigo

    It’s actually been done

    It’s actually been done already. For the Dirty Kanza 200 mile gravel race, Amanda Nauman mounted XTR M987 brake calipers and matched it to RS785 STI levers.

    http://www.bikeradar.com/road/gear/article/amanda-nauman-dirty-kanza-200-niner-bsb-9-rdo-pro-bike-47224/

     

    Apparently there are no incompatibilities between Shimano’s road and MTB hydraulic disc brakes. And yes, the BR-R785 is really just a roadgoing variant of the Deore XT BR-M785 brake caliper. The later BR-RS785 model effectively just eliminated the banjo fitting.

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