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  1. #1
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    What Type Of Postmount? 5'', 6'' 7'' ?

    Hi,

    I'm confused now. I Will install 180mm/160mm - Front/Rear Brakes and I don't know what type of postmount is the right for me.
    The brakes are Magura MT6.

    The fork is: 2013 Rock Shox Reba RLT Solo Air 29er
    Is it 6'' postmount - 180mm (postmount-caliper + adaptor)?
    Or 7'' postmount - 180mm (postmount-caliper)?

    And the frame's postmount is 74.2mm
    Is it 5'' postmount - 160mm (postmount-caliper + adaptor)?
    Or 6'' postmount - 160mm (postmount-caliper)?

  2. #2
    Never enough time to ride
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    The stock mounts on the Fork will be for a 160mm rotor, you will have to use a +20mm or 180mm (same thing different name) adapter for the 180mm rotor.

    I'm not understanding your description of the rear brake mounts. If they are a postmount type on the rear then no adapter is required for a 160mm rotor. If it's the tab (i.s.) type mounts you will need a REAR 160mm i.s. to post mount adapter.

    happy trails...

    squish
    Get out and ride!

  3. #3
    rebmem rbtm
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    That fork has 6" post mounts so a 180mm PM to PM adapter will be needed for a 180mm rotor.

    No idea what frame you have or what size the post mounts are on it.
    Some frames have 5" post mounts, some frames have 6" post mounts.
    If it has 5" post mounts you'll need to to use a 180mm PM to PM adapter for a 160mm rotor.
    If it has 6" post mounts then no adapter will be needed for use with a 160mm rotor.

    To see what size post mounts are on it you could:
    1) ask the frame manufacturer
    2) look for some specs on the frame
    3) ask the seller of the frame
    4) mount the brake caliper and see if it lines up with a 160mm rotor
    5) measure the brake mounts

    What Type Of Postmount? 5'', 6'' 7'' ?-shimano-rear-post-brake-spec.jpg

  4. #4
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    Thanks! That was very helpful!

  5. #5
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by Constantinos View Post
    Hi,

    I'm confused now. I Will install 180mm/160mm - Front/Rear Brakes and I don't know what type of postmount is the right for me.
    The brakes are Magura MT6.

    The fork is: 2013 Rock Shox Reba RLT Solo Air 29er
    Is it 6'' postmount - 180mm (postmount-caliper + adaptor)?
    Or 7'' postmount - 180mm (postmount-caliper)?

    And the frame's postmount is 74.2mm
    Is it 5'' postmount - 160mm (postmount-caliper + adaptor)?
    Or 6'' postmount - 160mm (postmount-caliper)?
    Use the precise rotor size. The fork has post mounts for direct mounting with 160mm rotors.

    5-inch, 6", 7" are nominal sizes and far enough different from actual rotor sizes to cause problems if you use the wrong rotor. The companies that insist on using the "inch" labels are just stupid and doing a disservice to the users. The most common sizes are 140, 160, 180 (almost but not quite 7"), 185, 200, 203mm. Only the last is an even inch diameter (8").
    mtbtires.com
    The trouble with common sense is it is no longer common

  6. #6
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    Actually, It's a Chinese Carbon Frame fro Hong-Fu Sport. They can't answer if it's postmount 5'' or 6''. The frame model is FM056. It has the same exact dimensions of SCOTT Scale 900 SL Bike.
    Attached Thumbnails Attached Thumbnails What Type Of Postmount? 5'', 6'' 7'' ?-1.jpg  


  7. #7
    rebmem rbtm
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    The SCOTT Scale 900 SL has 160mm / 6" post mounts.

    http://www.scott-sports.com/global/en/technology/bike/Tubular_Structure/

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