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  1. #1
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    XTR 975 Brake Adapter help- IS caliper -> Manitou Fork POST mount

    Hey all..hopefully a quick/easy question.

    XTR brakes BR 975 IS MOUNT (160F/140R) needing to go on a Manitou Minute Post MOUNT fork.
    160mm rotor

    What adapter will work?
    A general post noted something like this.
    Avid Disc Adapters Front Disc Adapters Detail Page

    HOwever...I found a full XTR adapter setup by searching XTR Brake Adapter.

    Shimano Front Disc Adpator SM-MA-F180S and P (fits 51mm front caliper, 74mm) in Tree Fort Bikes Frame/Fork Adapters (cat439)

    Any one ever have any luck making this work?
    Attached Thumbnails Attached Thumbnails XTR 975 Brake Adapter help- IS caliper -> Manitou Fork POST mount-100_8626.jpg  

    Last edited by illcomm33; 10-22-2011 at 09:58 PM. Reason: more info

  2. #2
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    I've used the Shimano adapter before and it works great. To the bet of my knowledge its the only Shimano adapter that will work for IS 51 -> post mount. Centering the caliper over the rotor is kind of a pain though. I used super thin washers to fine tune the position of the adapter.

  3. #3
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    Bikefridge have a good selection, should be straightforward...
    Only problem will be if you have the 'old' Manitou (69mm) spacing, in which case much less choice. I have this 69mm, got round it by buying a post adaptor (74mm) and re-drilling at 69. Been fine so far (Been a month, now)

  4. #4
    FM
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    I've run Shimano IS mount calipers on post-mount forks, on several bikes over the years, using shimano adaptors.

    However, as I recall the 160mm rotor is a no go with shimano, upsizing the rotor is required to get everything to line up. Note that your treefort link is specifically for a 180mm rotor. I think I had a 170 rotor and adapter on my manitou fork, then 203mm rotors on Marzocchi forks, all with 51mm IS calipers and 74mm post mounts on the forks.

    I do have 1-2 of these, if you are interested in a 203mm rotor, feel free to PM me.


  5. #5
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    Thanks for everyones responses.
    1) From what I can tell if I do run the adapter it has to be used with a 180MM rotor. These brakes would be going on a 29er SS and not sure if that makes sense.

    2) The rear caliper is the traditional (more common I think) post mount style. Would it make sense to just switch calipers? Put the 160f/140 Rear in the back? HOw good are those 4 inch rotors?

    $40 for and adapter + $ for a new 8 inch rotor....I might be selling these before trying to make them work.

  6. #6
    dru
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    Rear caliper mounts are still I.S. except for older stuff and the odd manufacturer here and there. The fork manufacturers started switching to PM a few years ago from IS which was the standard around a decade ago.

    If you want to go 140mm on the back use the front caliper you show in the picture (it will fit). If your other caliper is P.M. (you said it was?) just bolt it right to that fork and use a 160 mm rotor.

    Here's my exact set up on my Salsa El Mar. I don't think you need to go this route if you actually have a PM caliper, otherwise read on........

    I run XTR 975s with 2 identical XTR 160f/140r calipers which are both I.S. My bike had a I.S. rigid fork with a 160 mm XTR rotor up front and the 140 mm rotor on the back. My family just gave me a PM Manitou Tower, so I went with a Hope I.S. to P.M. adapter and a 180 mm XTR rotor. Obviously the Shimano version will work too

    The 140 mm rotor works great in the back btw.
    occasional cyclist

  7. #7
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    Going to try 140mm rear with the IS mount

    Quote Originally Posted by dru View Post
    If you want to go 140mm on the back use the front caliper you show in the picture (it will fit). If your other caliper is P.M. (you said it was?) just bolt it right to that fork and use a 160 mm rotor.

    The 140 mm rotor works great in the back btw.
    Thanks for the solid response and guidance Dru. My buddy was going to trade me his post mount XT's for the XTR's but when we tried to mount up the front IS XTR on his 2008 (?) Reba 29er (IS) the rotor was not lining up at all. It seemed that the rotor would need to go in towards the hub since the caliper was mounted with no spacers. Ditched that idea and am keeping the XTR's.

    Swapped calipers/lever and re-bled. Got the post mount installed on the front and it works great. Going to pick up 140 mm for the rear today. By the way for anyone who is following the fork is a Minute 29er and the frame is a Spot Longboard 29er.

  8. #8
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    No good

    Quick follow up.

    Got the 140mm rotor and was excited to get the install done.

    Problems.

    The Spot has a sliding dropout to tension the belt which moves the rotor way back in the dropouts...that length backwards jacks up the angle and causes the top of the caliper to hit the top of the rotor. This wouldn't be an issue if the belt tensioned near the front of the dropouts. Not worth fiddling with buying a shorter belt.

    FIgured I would let subscribers know. The 140 rear seems like a neat design on a vertical dropout (or comparable) bike.

    Damn.

  9. #9
    rebmem rbtm
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    The following adapter might work to fit your IS caliper on your PM fork.

    KCNC Disc Brake Adapter Post Fork - IS Caliper 160mm

  10. #10
    dru
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    I'm taking a guess here, but your rear mounts for the caliper are just holes and not slots? If so how are you supposed to line up the caliper after you tension the belt? I've been scouring the 'net looking fro pictures but all seem to be the drive side only. I'm sorry that the 140 mm isn't working out in your particular case, I feel kind of bad that things on your frame are causing issues. Put up a picture of your frame from the brake side so I can see what's going on.

    Drew
    occasional cyclist

  11. #11
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    quick question related to xtr IS calipers. What if I ran an XTR IS caliper on frame that uses IS mount? And if the rotor I ran on that back tire was hayes and 160mm.

    I tested it out last night and it works as a direct fit, without any adapter. However, I get a ton of squealing. Could it be because the calipers IS mounts were meant to mount to an adapter first and not direct?

  12. #12
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    Are the IS tabs on the frame faced and clean? Did you use the spade spacers to align the caliper with the rotor so it's centered?
    I'm a member of NSMBA and IMBA Canada

  13. #13
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    Just saw this post, pics included

    Quote Originally Posted by dru View Post
    I'm taking a guess here, but your rear mounts for the caliper are just holes and not slots? If so how are you supposed to line up the caliper after you tension the belt? I've been scouring the 'net looking fro pictures but all seem to be the drive side only. I'm sorry that the 140 mm isn't working out in your particular case, I feel kind of bad that things on your frame are causing issues. Put up a picture of your frame from the brake side so I can see what's going on.

    Drew
    Drew,
    Sorry I didn't reply but I never got the email/pm that someone posted.
    I uploaded a pic so you can see the sliding IS slots look like. I bet the 140 would work like a champ when the axle is all the way at the front. With a chain I could take out links to make that happen...with the belt not so much. The whole orderal makes sense though...Even when I was running a 160 rotor in the rear with the standard post mount XT Caliper, I still had to raise it up with spacers to keep the rotor away from the caliper. I ordered one of the HOPE Post/IS mount conversion adapters from Chain Reaction which should be in sometime this week. Going to swap the calipers back again. Another lesson hopefully learned.
    Attached Thumbnails Attached Thumbnails XTR 975 Brake Adapter help- IS caliper -> Manitou Fork POST mount-img_1055.jpg  


  14. #14
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    Double check the rotor alignment

    Quote Originally Posted by aa240sx View Post
    quick question related to xtr IS calipers. What if I ran an XTR IS caliper on frame that uses IS mount? And if the rotor I ran on that back tire was hayes and 160mm.

    I tested it out last night and it works as a direct fit, without any adapter. However, I get a ton of squealing. Could it be because the calipers IS mounts were meant to mount to an adapter first and not direct?
    I also would suggest making sure the rotor is centered between pads. Also make sure the rotors are clean of any residue. Lastly you could always consider organic compound pads. They burn up quicker but are really quiet (my wife uses them with her Avid Ultimates...not 100% sure where to get Shimano ones)
    Good luck!

  15. #15
    dru
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    Quote Originally Posted by illcomm33 View Post
    Drew,
    Sorry I didn't reply but I never got the email/pm that someone posted.
    I uploaded a pic so you can see the sliding IS slots look like. I bet the 140 would work like a champ when the axle is all the way at the front. With a chain I could take out links to make that happen...with the belt not so much. The whole orderal makes sense though...Even when I was running a 160 rotor in the rear with the standard post mount XT Caliper, I still had to raise it up with spacers to keep the rotor away from the caliper. I ordered one of the HOPE Post/IS mount conversion adapters from Chain Reaction which should be in sometime this week. Going to swap the calipers back again. Another lesson hopefully learned.
    Thanks for getting back to me! Yeah, looking at your picture you've got about twice the adjustment range for the rear wheel as you do for the caliper, no wonder the disc his hitting the caliper if you pull that wheel all the way back.

    How much are belts? I'd want to try a shorter one instead of mucking around with adapters and such. A friend runs the Gates and it has to be super tight or it 'pops'.

    Are you also switching lines around every time are are you just running the levers MC style? If the former, you must have gotten very good at bleeding brakes!

    Good luck with however you end up plumbing that bike! Make sure you put up a picture of it when you are finished.

    Drew
    occasional cyclist

  16. #16
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    Quote Originally Posted by dru View Post

    How much are belts? I'd want to try a shorter one instead of mucking around with adapters and such. A friend runs the Gates and it has to be super tight or it 'pops'.

    Are you also switching lines around every time are are you just running the levers MC style? If the former, you must have gotten very good at bleeding brakes!

    Good luck with however you end up plumbing that bike! Make sure you put up a picture of it when you are finished.
    Drew
    Thanks for the reply. Belts are like $55 and I wouldn't be certain that a shorter belt would be the sweet spot. I was orginally trying to sell the frame/belt combo but wasn't having much luck. Decided to part it back together with parts I had.
    I did switch the levers so bleeding was required but that is the pure beauty of Shimano. Very simple overall. *(not like the Avids where you have to do like 3 steps and a magic dance to get them bled.)
    As for the belt popping. I have been racing on belts for 3+ years and only had a belt pop on me 1 time...and that was because my rear DT SWISS RWS came loose!
    If your buddy is having issues I would suggest he get the gates "Cricket" belt tensiometer. It is a slick tool that measures tension. Look around though because the "bike specific" tensiometer is the same one as one of their "car specific" tensiometer...Gates simply added a sticker and about $40 to the price.

  17. #17
    dru
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    Quote Originally Posted by illcomm33 View Post
    If your buddy is having issues I would suggest he get the gates "Cricket" belt tensiometer. It is a slick tool that measures tension. Look around though because the "bike specific" tensiometer is the same one as one of their "car specific" tensiometer...Gates simply added a sticker and about $40 to the price.
    I'll let him know. He and another friend always like or have all the gadgets for doing things on the bike.

    Drew
    occasional cyclist

  18. #18
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    Lots of spacers.:)

    Quote Originally Posted by dru View Post
    Thanks for getting back to me! Yeah, looking at your picture you've got about twice the adjustment range for the rear wheel as you do for the caliper, no wonder the disc his hitting the caliper if you pull that wheel all the way back.

    How much are belts? I'd want to try a shorter one instead of mucking around with adapters and such. A friend runs the Gates and it has to be super tight or it 'pops'.

    Are you also switching lines around every time are are you just running the levers MC style? If the former, you must have gotten very good at bleeding brakes!

    Good luck with however you end up plumbing that bike! Make sure you put up a picture of it when you are finished.

    Drew
    Drew,
    Got the hope caliper adapter and swapped back the calipers (IS to the front and post to the rear) See the pics
    Ever since I upgraded the Hayes Stykers to the Shimano (XT and XTR) I have had to use spacers/washers to get the rear caliper to clear the rotor .
    PITA when I need to remove the rear wheel.
    Hope the pics help others with similar situations (pay if forward right). I found that HOPE adapter at Chain Reaction cycles for 17 but it also require a 180mm rotor.
    Attached Thumbnails Attached Thumbnails XTR 975 Brake Adapter help- IS caliper -> Manitou Fork POST mount-100_8668.jpg  

    XTR 975 Brake Adapter help- IS caliper -> Manitou Fork POST mount-100_8670.jpg  


  19. #19
    dru
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    I'm glad you've managed to get it all working although it is really too bad the frame designer/belt drive forced you into that corner. You've had to add a bit of weight with adapters and such which is unfortunate because the XTR stuff is stupid light. I see how you've gotten around the clearance issues on the back with those washers sandwiched under the mount. As for running 180 up front, I'm guessing you like it fine. I ran 160 before and found the power lacking. The 180 is a very nice improvement power and feel-wise with the 29er wheel.

    Drew
    occasional cyclist

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