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  1. #1
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    Shim caliper or disc hub?

    I recently purchased a second wheelset to avoid the pita of changing my tires. I'm fairly proficient at tire changing, but my Schwalbe Marathon commuter tires are very difficult to mount; a good excuse for another wheelset. Only takes me about 5 minutes to swap the wheelsets.

    I have an issue with the rear caliper rubbing the disc on the new wheelset.

    Frame is a Cannondale Caffeine, brakes are juicy 5's, rubbing wheelset has a DT Swiss 370 hub. Problem is that the rotor rubs the brake pad closest to the hub. I've gone through the usual Juicy5 adjustments: spread spread brake pads, loosen CPS bolts and center caliper. Doesn't quite work with the 370-equipped wheel; if the rotor were moved <.5 mm away from the hub, all would be fine.

    I stumbled across Syntace disc shims. They're .2mm thick and have a shape similar to the cross section of a hub. Seems ideal for my situation.

    I called a few LBS check availability. Both tried to steer me away from the hub shim approach. One recommended enlarging the adjustment slot on the calipers. The other suggested moving the caliper mount with thin washers. I would only take the dremel to the caliper as a last resort. I'm reluctant to shim the caliper mount since my original wheelset fits fine without any shims; admittedly if I could find thin enough SS washers it would likely work fine.

    I'm not sure either LBS was familiar with the Syntace shims since both voiced strength concerns. I tried to explain it was a shim designed for exactly the problem I am experiencing and that I wasn't proposing shimming the six mounting bolts.

    Are the Syntace shims the best solution for my problem?

    Thanks

  2. #2
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    The Syntance shims do look like they will sort your problem, i can't see any problems with using them.

  3. #3
    ...idios...
    Reputation: SteveUK's Avatar
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    Quote Originally Posted by zaphod123
    Both tried to steer me away from the hub shim approach. One recommended enlarging the adjustment slot on the calipers.
    WTF? So they figure it's OK to remove material from a caliper, which would automatically make piston alignment impossible, but safely shimming a rotor is a no-no? You need to find a new shop.

    Shimming the caliper inboard or the rotor outboard are both perfectly safe - if done properly - and perfectly logical. If you don't want to do the caliper, then 1mm rotor shim (like this) sounds like it would do just the job for you.
    .
    .


    What luck for rulers, that men do not think - Adolf Hitler

  4. #4
    Meh.
    Reputation: XSL_WiLL's Avatar
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    It is fine to shim the rotor/hub. You can shim the rotor to approximately the same position on both hubs so you don't have to adjust and center the caliper every time you swap wheels.

  5. #5
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    Quote Originally Posted by XSL_WiLL
    It is fine to shim the rotor/hub. You can shim the rotor to approximately the same position on both hubs so you don't have to adjust and center the caliper every time you swap wheels.
    I will indeed shim the rotor to approximate my other wheel. I'm curious why the DT hub equipped wheel is in need of shimming. I realize manufacturing tolerances exist, but I would think it should be within the range (~2mm) that the caliper adjustments allow. As it stands, that particular wheel cannot work correctly without shimming; thankfully it's a simple fix.

    Thanks

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