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Thread: Which IS/Post brake adaptor?

  1. #1
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    Default Which IS/Post brake adaptor?

    Could you please help me understand IS to Post mount adapters?

    I recently pickup up last year's SC Tallboy 3 frame which has an IS style mount for the rear brake. I am planning to use a SRAM post mount brake caliper with a 160mm rotor. What IS/post adapter do I need to ensure that the caliper and rotor position correctly? The included manual doesn't discuss the requirement.

    I see this one which seems to be a for a sram adapter for 160 rear rotors.
    F-180mm/R-160mm / 74mm / 51mm / Fork/Frame (20 IS)

    More generally, is the assumption that IS mounts are positioned the same distance relative to the axle for all bikes, such that one can assume that a bracket having a certain amount of offset will always work for a specific rotor size?
    Steve Park

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    Default Re: Which IS/Post brake adaptor?

    The caliper itself has the in/out adjustment built in (a slightly slotted bolt hole). So given the correct +20 IS/post adapter for the caliper (they're not universal in their fit-up to the caliper), you'll be good.
    DT

    http://www.mjolnircycles.com/

    Some are born to move the world to live their fantasies...

    "the fun outweighs the suck, and the suck hasn't killed me yet." -- chasea

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    Default Re: Which IS/Post brake adaptor?

    Quote Originally Posted by David Tollefson View Post
    The caliper itself has the in/out adjustment built in (a slightly slotted bolt hole). So given the correct +20 IS/post adapter for the caliper (they're not universal in their fit-up to the caliper), you'll be good.
    Got it with respect to the slotted bolt hole for minor adjustments.

    ...assuming away any brand specific fit-up of the caliper.
    Are rear IS holes always positioned on the frame at +0 for 140 as an industry standard? In other words, does one always use a +20 IS/Post adapter to mount for a 160 rear?
    Or is the position of rear IS holes not a standardized thing?
    Steve Park

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    Default Re: Which IS/Post brake adaptor?

    Quote Originally Posted by sparky33 View Post
    Are rear IS holes always positioned on the frame at +0 for 140 as an industry standard?
    Yes.
    DT

    http://www.mjolnircycles.com/

    Some are born to move the world to live their fantasies...

    "the fun outweighs the suck, and the suck hasn't killed me yet." -- chasea

    "Sometimes, as good as it feels to speak out, silence is the only way to rise above the morass. The high road is generally a quiet route." -- echelon_john

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    Default Re: Which IS/Post brake adaptor?

    I learned something today.
    Thank you!
    Steve Park

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