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  1. #1
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    Converting to 140mm rears

    Anyone done it?

    Right now I have 965 XTR Dual Control and would like to convert to 140mm rear (SMRT97SS)

    It looks as though I can run a BR-M965-F caliper and that will give me the size I need for the smaller rear rotor.

  2. #2
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    Correct, the front caliper in the rear will bring the size down to 140mm.

  3. #3
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    Thanks for the reply. No issues running front calipers in the rear? Or rear calipers in the front?

  4. #4
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    I run an m965 rear caliper on my front fork. Allows me run a 180mm disc without the need for an adapter - looks neat and tidy and is lighter set-up to boot.. I have no issues whatsoever. I suspect you won't have any issues running the front caliper on the rear.
    Never cross a river because it is on average 4 feet deep.

  5. #5
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    I'm running a m965 160mm front caliper on the rear to fit a 140mm rear rotor. It works fine.

  6. #6
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    Thanks.

    Any special tips on replacing the caliper besides bleed, bleed, bleed?

  7. #7
    Meh.
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    Use a new barb and compression olive. Bleed.

  8. #8
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    Can you explain a little more what the barb and compression olive are?

    Compression olive sounds self-explanitory. Barb?

    Thanks

  9. #9
    Meh.
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    A barb is inserted into the end of a hose. Both are used to help seal the connection.


  10. #10
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    Thanks for the reply. I did find a schematic of the caliper. It seems the olive and barb are employed at the brake handle end and there are only o-rings on the caliper side of things.

    http://techdocs.shimano.com/media/te...9830609096.pdf

  11. #11
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    Assuming bkish uses the same cable and doesn't need to modify it's length, why would he need a new barb and compression olive? He wouldn't even need to disconnect the olive side of the cable from the lever. Basically, the process I used in changing calipers is simply to disconnect the hose from the old caliper and attach the new one, then bleed.
    Never cross a river because it is on average 4 feet deep.

  12. #12
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    140 to 160mm

    I'm trying to do the complete opposite. Change from 140 to 160 with an XTR 975 Dual Control. Does anyone know if I need a new caliper or just an adaptor?

  13. #13
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    I have completed the change over to the 140 rear. An interesting exercise for a 60 (?) gram weight savings. Didn't cost me anything except $14 for the rotor from Santa Cruz.

    I have 3 rides on the new set up and have noticed a bit less power but mostly I notice less modulation. It's not bad, just different.

    Not sure why you would lose power with a smaller rotor becase the pad/rotor contact area and tire to ground braking surfaces are the same for 140 and 160. I can see more fade becase a smaller rotor cannot dissipate heat as readily, but from a mechanical standpoint the actual friction surfaces (rotor/pad and tire/ground) are the same for 140 and 160.

    I think to change from 140's even with 975 you would need a new caliper. I can see no way an adaptor would work.

  14. #14
    Meh.
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    The moment lever arm is smaller. It's the same reason a larger rotor has "more power."

    I noticed it was easier to control the brake with the smaller rotor.

    A +20mm IS to IS adapter may be able to be mounted. If it's a post mount caliper, only a new adapter is needed.

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