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  1. #1
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    Reputation: sodade's Avatar
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    Disc hubs are not all the same!!

    I had it all figured out. My plan was perfect. I was going disc on both of my MTBs. I bought two sets of Marta Sls - 1 for each bike. If something goes wrong - I can always swap em.

    The plan was to have two sets of wheels - one lightweight (stans rims laced to CK hubs) - the other a bomber set (XT laced to 317s). As they both would have the Magura Marta rotors mounted, I could swap wheels between bikes depending on the type of riding. Brilliant!

    well maybe...

    I set up the calipers on the HT relative to the CK wheels and when I mount the XT wheels, the rotor is in a different position and thus rubs hard against one caliper. Same problem on the other bike. Arrgg. The difference is probably a couple of MM, but it is enough to destroy my plans for total wheel flexibility. Arrggg.

    I guess that the IS (international standard) does not include rotor placement relative to the dropouts? If it does, I wonder who screwed up? Shimano or CK?

    I guess that I could put in washers at the caliper mounts each time I wanted to switch, but that kinda ruins the point and getting the calipers positioned correctly was such a time consuming nightmare that I am afraid to have to deal with it pre-ride.

    Has anybody else been in my shoes? Any helpful hints?
    Wave upon wave of demented avengers
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  2. #2
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    i am not sure, but i think the international standard does not standardize the rotor mount-dropout position. only to the extent that in principle every i.s. caliper can be brought into proper alignment with the rotor using washers.

    my guess is that your wheelswapping plan would only work with identical hubs, and probably not even then, because the rotors on the different wheels might be warped a little bit.
    this is (improbably) one reason for the rubbing, that your rotors on the respective wheels are slightly out of true, this can be cured (there are various rotor truing links in this forum).

    however, i think you will have to reposition the calipers every time you switch wheels
    but then again, i have never attempted getting a setup like this to work...

  3. #3
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    Ahhh, you found out the HARD way :(

    The ONLY sure way to do what you WANTED to do is to have both wheelsets built with the same hubs.....even then it is "possible" (but not probably) that the rotors might not match up exactly.
    Disc Hubs between manufactures will allign the rotors differently.....hence the reason disc companies supply your disc brakes with all sort of different thickness shims.
    Look on the bright side....you can now build your other wheelset with King hubs

    KMan



    Quote Originally Posted by sodade
    I had it all figured out. My plan was perfect. I was going disc on both of my MTBs. I bought two sets of Marta Sls - 1 for each bike. If something goes wrong - I can always swap em.

    The plan was to have two sets of wheels - one lightweight (stans rims laced to CK hubs) - the other a bomber set (XT laced to 317s). As they both would have the Magura Marta rotors mounted, I could swap wheels between bikes depending on the type of riding. Brilliant!

    well maybe...

    I set up the calipers on the HT relative to the CK wheels and when I mount the XT wheels, the rotor is in a different position and thus rubs hard against one caliper. Same problem on the other bike. Arrgg. The difference is probably a couple of MM, but it is enough to destroy my plans for total wheel flexibility. Arrggg.

    I guess that the IS (international standard) does not include rotor placement relative to the dropouts? If it does, I wonder who screwed up? Shimano or CK?

    I guess that I could put in washers at the caliper mounts each time I wanted to switch, but that kinda ruins the point and getting the calipers positioned correctly was such a time consuming nightmare that I am afraid to have to deal with it pre-ride.

    Has anybody else been in my shoes? Any helpful hints?

  4. #4
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    There might be a solution

    I saw this in the German BIKE of November 2003:

    Syntace makes Disc Shims.
    (site is in German)
    You can use those to fine position the disc, instead of using washers to position the caliper.


    About the distance from the side of the hub to the contact of the disc. It is included in the IS (i think) and is 10.16mm+/-0.1 for the front and 15.27mm+/-0.1 (according to a Avid tech manual).
    The problem for you are those +/- 0.1 margins.

  5. #5
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    IS includes the correct offset of the rotor.
    Meaning all hub manufacturers were informed and when finally shimano switched, everybody else ( almost ) followed. That was some 4 - 5 years ago...

    It does bother me that some hubs are still not on par. That shouldnt happen anymore.

    Thorsten

  6. #6
    Sublime Absurdity
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    So, are you saying that Chris King didn't follow the standard?
    Wave upon wave of demented avengers
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  7. #7
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    where do you read that in my post ?

    I am sad that some parts do not fit ( are interchangeable ) and the consumer has all the trouble to adapt to a situation, which he should not have to worry about.

    As long as you have to tweek a walmart bike, to make things work ( at least somewhat) I can understand, but if you buy first class ( and expensive ) stuff , it should fit together.
    No matter what brand.

    Thorsten

  8. #8
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    Well, you said that the IS includes rotor offset and that Shimano made the switch to IS 4-5 years ago and that almost everyone switched. The rotor offset is different between my Shimano XT and my Chris King hubs so I am hoping to figure out which one of them isn't following the IS. The rotor offset is a little more than 1MM.

    Frankly, I was hoping that I could blame Shimano and get Jenson to take the shimano hubs back.

    I wonder if American Classic or Hugi hubs will have the same offset as the Chris Kings?
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  9. #9
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    Actually, I was wrong - the difference is about .4mm and the Shimano's are about 9.7 on the front (*******s!). Later today, I will take the rotors off and get a precise measure on both...
    Wave upon wave of demented avengers
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  10. #10
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    Quote Originally Posted by sodade
    So, are you saying that Chris King didn't follow the standard?
    I just contacte King re this situation. Apparently it is a fork tolerance issue in my case.

    From: Jen Klish
    Sent: Monday, March 08, 2004 10:55 AM
    Subject: Re: clearance issues with Iso front hubs and Fox forks

    Hi Bill,

    I have heard of this issue with about every imaginable combination of fork and brake. All I can offer to do for you is to have you send in your hub and we will measure it in our machine shop to make sure it it within the ISO tolerance specifications of .401" +- .010". Since we have been manufacturing the ISO hub I have never had one come back that was out of spec. You are still welcome to send it back though. Please let me know if you would like to send it back and I will assign you an RA#.

    A good thing to keep in mind is that machining is a more accurate manufacturing process than casting of forging.



    Thanks for your patience. We have recently relocated to Portland and are still getting settled in.

    JEN
    Tech/Warranty
    King Cycle Group
    2801 NW Nela Street
    Portland, OR 97210
    503.972.4050

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