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  1. #1
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    Who makes post to post mount rear adapters???

    I have a Stumpy Carbon hardtail and the rear brakes are post mount, not IS. I am not looking for IS to post adapters, I need post to post.

    The stock brakes are Avids which I want to get rid of, but the adapters are avid specific because they have the cone macined into them for the CPS system.

    Who makes post mount spacer/adapters for the rear???

    Thanks

  2. #2
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    Actually, you should be able to use the Avids adapters for other post mount brakes. I use Avid adapters all the time with my Shimano brakes. The Avid caliper accounts for the CPS washers. The only thing to watch out for is Avids uses a 185mm rotor, while many others are 180mm, but you did not mention changing rotors.

  3. #3
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    Quote Originally Posted by RSabarese View Post
    Actually, you should be able to use the Avids adapters for other post mount brakes. I use Avid adapters all the time with my Shimano brakes. The Avid caliper accounts for the CPS washers. The only thing to watch out for is Avids uses a 185mm rotor, while many others are 180mm, but you did not mention changing rotors.
    I thought about this but those adapters don't seem very solid with the coned cut out for the CPS system. Certainly someone else out there makes adapters...

  4. #4
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    Interesting, all the adapters I've seen from Avid are flat, not concave. Can you post a photo? What year is your stumpy? What size rotor are you running?
    I wonder it it follows the same pattern as IS? Meaning, 160mm rear, is pretty much the same as 180mm front. If that hols true, you may get away with a 180mm front adapter on the rear. Let's see if pics can help us out though as I have not heard of post mount rear.

  5. #5
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    Lots of new bikes have post mount rear now as it is lighter and stiffer then IS with an adaptor. Unless you are using a DH bike or a Clyde then you wouldnt really need anything bigger then the stock 160mm rotor size. If you want better modulation or heat dispersion get better brakes, bigger rotors won't quite compensate. With that in mind, any 160 front will work as a 140 rear, any 180 front will work as a 160 rear, etc. And as for the hope 183 size or avids 185 size. Usually they are all compatible. If the rotor is hitting throw some washers in.

  6. #6
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    Quote Originally Posted by Lipster94 View Post
    Unless you are using a DH bike or a Clyde then you wouldnt really need anything bigger then the stock 160mm rotor size. If you want better modulation or heat dispersion get better brakes, bigger rotors won't quite compensate.
    My original post says nothing about going bigger, only wanting to get away from Avid. I am planning to stay at 160mm rotors as this is a dedicated race bike, although I am a clyde. For the record, I want to run XTR race brakes.

  7. #7
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    Quote Originally Posted by RSabarese View Post
    Interesting, all the adapters I've seen from Avid are flat, not concave. Can you post a photo? What year is your stumpy? What size rotor are you running?
    I wonder it it follows the same pattern as IS? Meaning, 160mm rear, is pretty much the same as 180mm front. If that hols true, you may get away with a 180mm front adapter on the rear. Let's see if pics can help us out though as I have not heard of post mount rear.
    These are not your conventional adapters as you will see in photos below. Stumpy HT Carbon is 2011 with 160mm rotors. In the front, there is no adapter as usually you just mount 160mm brakes directly to the fork, but these are avid so you have the CPS stack as well. Check out my pics of the rear set up. They are more like spacers than adapters... Note the different heights as well. Also pictured is a close up of the spacer with the cone shape and how the cps cone mates up...








  8. #8
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    Quote Originally Posted by Lipster94 View Post
    With that in mind, any 160 front will work as a 140 rear, any 180 front will work as a 160 rear, etc. Usually they are all compatible. If the rotor is hitting throw some washers in.
    Good info on 180 front =160 rear and I will have to try that out.

    Yeah, you will see I am running some washers right now to try to get better pad contact with my XT rotors, but I really think the biggest issue is the BS CPS mounting system. I don't know how they think they will ever get a solid mounting platform stacking 4 pieces on top of eachother. Just more components to cause vibration... Of course me adding washers to the stack only increases the potential for chatter

  9. #9
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    After I posted similar info, I found your frame on the spesh website. It says the post mounts are 140mm and 160mm rotor, so that stands to reason you should be able to get a 180mm front post mount and it will bolt up fine to a 160mm rear. Infact, looking at your pics, it says 140mm front with 160 rotor, so I think you're okay to buy the 180mm rear.

  10. #10
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    Just spent some time looking at the Specialized website and the 2012 models and I do not think using a 180 post mount adpater will work in this case, but I will have to try it before I say for certain.

    If you do a zoom in on any of the carbon bikes that use non avid brakes and have a 160mm rotor in the rear, you will see the adapter I am looking for. On a front post to post adapter, it staggers the caliper in one direction offset from the adpater to fork mounting bolts and this also sets the correct alignment with the rotor.

    On the new bikes with 160mm rear post mount, the adapter does not stagger. It just uses one bolt rhough the caliper, through the adapter and into the frame. Not sure why I am having such a hard time finidng this adapter.

    The XTR Sworks stumpy and the Expert Stumpy have different brakes, one XTR Shimano and one Formula R1, but htey are using identical rear adapters.

    I havebeen to the Shimano sites, Formula site, and am unable to find a 160mm rear post adapter

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