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  1. #1
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    hayes rotor thickness vs sram rotor thickness for bb7's

    im looking to buy another set of wheels so i can have street tires on one and dirt tires on the other also so i have heavier duty wheels on the dirt tires still riding the mavic 223's

    theres a set im interested in and they have hayes rotors on them im hoping there the same thickness so i dont have to completely re setup everytime i swap wheels

    im gonna head to the shop and measure my rotors that come with the bb7's
    GT idrive 4 need to find some more trails out here!!!!!!!!!!!!!!!!!!!!!!!

  2. #2
    Meh.
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    The rotors won't be your problem. The thickness will vary by a fraction of a millimeter if at all. You do have to worry about the hub spacing though. Each hub may position the rotor slightly more in or out than the other. You may have to try to get them to match up by using shims between the rotor and the hub on one of the wheelsets.

  3. #3
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    i figured they would be within a few thousanths, i have xt hubs on current wheels and new wheels will be xt also so i will be covered there also

    thanks!!!
    GT idrive 4 need to find some more trails out here!!!!!!!!!!!!!!!!!!!!!!!

  4. #4
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    If you are running...

    160mm rotors it shouldn't be a problem. If you are running a 185mm on the front then you'll have a problem. That 5 extra mm on the Avid rotor (and adapter) does make a difference. That and the Hayes 7" rotor is a 178mm not a 180. So you could have a few problems there. But the 160's are a wash.

    What XSL_WiLL is telling you though is that you are VERY unlikely to get two wheel sets that will match up even using hubs of the same brand and model. Manufacturing tolerances WILL make for some adjustment requirements when shifting from one wheel set to the other. The problem being is you are talking more than just a few thousandths when you add it all up. There are multiple tolerances involved, the calipers, overlocknut tolerances on the hub, machining tolerances of the rotor mount on the hub, machining tolerance of the rotor, etc. They all add up and all can effect where the rotor sits in relation to the caliper. That's why calipers are manufactured with the mounting holes sloted.

    Usually though it's close enough that you can make adjustments through the use of shims either under the rotor or under the caliper mount adapter to compensate for the differences. And your choice of brakes makes it even easier. The inboard and out board adjusable pads of the BB7 help allot.

    The closest I've ever come to an "adjustment free" double wheel set set up was with a set of identical shimano XT hubed wheels, one for off road and one for commuting. The off road set was the bench mark set, the commuter I had to make minor adjustments for. But minor they were, when going to the commuter set I had to back the inboard pad out one click and the outboard pads in two clicks on the front and the inboard pad out one and the inboard in one on the rear. This was to get them to feel the same at the lever, and eliminate rub on the rear. And it was before shimming. I ended up putting .5mm shims under the rotors on the commuter wheels and I could just switch them out with no adjustments, but they still didn't feel quite the same. So some minor ajusting was necessary to get the feel right.

    The bottom line is, you will be extremely lucky if you get a second set of wheels that you can just swap over with absolutely no adjustments to the brakes or without the use of shims somewhere. Rotor thickness differences will likely only be a couple thousandths. But that ain't all that will likely be a couple of thousandths (more like huderedths) off. You have other components that will affect it too. And the sum total of those differences will require you to make ajustments. So be prepared!

    Good Dirt
    "I do whatever my Rice Cripsies tell me to!"

  5. #5
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    yeah i know im gonna have to buy a 185mm avid rotor. i just wanted to see if everything is gonna be close to make swapping fairly quick and simple. im gonna measure both sets of hubs to see about how close they are. if they are way out i will take them into the machine shop at work and have them match the front and rears so atleast the offset will be the same there. the wheels have 160mm rotors on both so i may take both 160's and run the two of them on the rears so there the same and buy another 185mm roundagon avid rotor so the fronts are the same then i just have a spare 160mm avid rotor.

    thanks again for the help
    GT idrive 4 need to find some more trails out here!!!!!!!!!!!!!!!!!!!!!!!

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