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  1. #1
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    IS to 203mm PM adapter ?

    I have old school four-pot XT calipers, they are IS mount. I just bought a Magura Wotan that has 203mm post mounts. Does anyone know if there is an adapter available that allow fitment of IS calipers to PM forks without increasing rotor size? Every thing that I can find requires at least a 10mm increase in rotor size, and I have spent quite a bit of time looking. I love these brakes and I really don't want to replace them if I don't have to.

    Thanks

  2. #2
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  3. #3
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    oops
    Last edited by SasquatchSC; 09-13-2010 at 07:00 PM.
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  4. #4
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    I can't tell for sure, but that one looks like it goes from 160mm PM to 203mm IS. The Wotan requires a 203 rotor minimum, and has direct post mounts for that size. I think basically I need a 160mmPM to 160mmIS adapter.

  5. #5
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    That one is the same as posted above.

  6. #6
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    oops part deux
    Last edited by SasquatchSC; 09-13-2010 at 07:00 PM.
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  7. #7
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    Indeed they don't, but the radius from the center of the axel to the mount face changes by 21.5mm between post mounts for a 160mm rotor and post mounts for a 203mm rotor. A post mount caliper bolts directly to the posts on my fork and requires a 203mm rotor.

  8. #8
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    It appears that Shimano part #ISMMAF160PSA should do the trick, but a second opinion would be good. It's Part #18669-7389 on Universal Cycles, but there is no picture of it.

    Edit: Here is a link to it, I'm pretty sure this the one. http://www.bti-usa.com/public/item/SH65570. Thanks for the help fellas.

    Edit again: Perhaps it is not the correct after all, it sounds right according to the description on Universal Cycles, but the part number returns IS mount to PM caliper everywhere else.
    Last edited by Zacsquatch; 09-13-2010 at 06:26 PM.

  9. #9
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    oops part 3: the search for spock
    Last edited by SasquatchSC; 09-13-2010 at 07:00 PM.
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  10. #10
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    If I used the F203S/P, then I would need a 246mm rotor. The post mounts on this fork require a 203 mm rotor with the caliper directly mounted on the fork. I need an adapter that goes from post mount to international standard with out increasing the rotor size.

    The pic shows it as it is mounted right now. This is a 203 rotor with a 170mm adapter attached to the posts. Note that I only have ~5mm of pad on the rotors braking surface. Basically I need a 160mm PM fork to 160mm IS caliper adapter.


  11. #11
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    ok now i see!! the fork's post mounts are already set for 203mm(as you said originally, but i somehow ignored completely!!!)

    my bad man! i'll delete my other posts so as not to confuse others!
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  12. #12
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    No worries man, a picture is worth 1000 words right? Good choice of monicer by the way.

  13. #13
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    There are no adapters that preserve the rotor size that I know of.

    Formula used to have some from Formula, but they worked only with some of their calipers that were really small, giving the adapter enough clearance.

    Seeme like you would need to siwtch to a PM caliper or go for a 220mm rotor (Formula makes one IIRC)

  14. #14
    rebmem rbtm
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    Quote Originally Posted by Zacsquatch
    Basically I need a 160mm PM fork to 160mm IS caliper adapter.
    KCNC have a 160mm adapter for IS brakes to PM forks that might be worth trying .

    http://clee-cycles.co.uk/cc/catalog/...roducts_id/989
    http://www.xcracer.com/shop/viewprod...?productid=103

    KCNC 160mm Adapter + PM fork + XTR calliper: Post Mount vs IS


    edit. looking at the size of that huge XT calliper I doubt that the KCNC adapter would work with it.

  15. #15
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    Yeah, that looks like it would do the trick, except for the size of my calipers. It's looking more and more like I am going to have to get different brakes. Bummer. Any want to trade me? haha.

  16. #16
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    Quote Originally Posted by cobba
    KCNC have a 160mm adapter for IS brakes to PM forks that might be worth trying .

    http://clee-cycles.co.uk/cc/catalog/...roducts_id/989
    http://www.xcracer.com/shop/viewprod...?productid=103

    KCNC 160mm Adapter + PM fork + XTR calliper: Post Mount vs IS


    edit. looking at the size of that huge XT calliper I doubt that the KCNC adapter would work with it.
    Damn you're amazing, I always thought no such thing exists... too bad the m755 is too long it'll hit the lower PM bolt if it gets any closer to the hub.

    Iono OP, do you love the brakes more or the fork more?

  17. #17
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    Quote Originally Posted by Zacsquatch
    Yeah, that looks like it would do the trick, except for the size of my calipers. It's looking more and more like I am going to have to get different brakes. Bummer. Any want to trade me? haha.
    If I understand your earlier comment correctly, the 160mm KCNC adapter mentioned above should suit your rotor as your forks accept a 203mm rotor with a standard caliper (which is set for a 160mm rotor without an adaptor).

    Tim

  18. #18
    rebmem rbtm
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    Quote Originally Posted by Wombat
    If I understand your earlier comment correctly, the 160mm KCNC adapter mentioned above should suit your rotor as your forks accept a 203mm rotor with a standard caliper (which is set for a 160mm rotor without an adaptor).

    Tim
    The huge 4 pot calliper he has is too big to fit on the KCNC adapter, it physically wouldn't be able to sit any closer to the fork then the 170mm adapter he currently has, if he had a smaller brake calliper it might work.

  19. #19
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    Cobba, thanks. I'm obviously missing something here. The original Shimano IS to PM mount required a 170mm rotor, as in the picture above, for that reason (can't otherwise get the caliper close enough to the fork). I though that this was the same issue with all IS front calipers (they needed a minimum 170mm rotor on an PM fork), and that KCNC had managed to overcome the issue.

    Is there something about the caliper that makes it different to other IS calipers?

    Thanks

    Tim

  20. #20
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    The thing that makes these different is the enormous size of the calipers. These are about twice as long most other IS calipers, so the bottom of the caliper hits the lower post before it can get any closer to the axle.

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