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rotor need truing after switching to different hub?

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rotor need truing after switching to different hub?

Old 04-23-19, 10:40 PM
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spectastic
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rotor need truing after switching to different hub?

my hubs are all 6 bolt. when i switch rotors to a different hub, the rotor somehow rubs with the new hub. My theory is the hub disc rotor mount holes weren't machined very precisely, causing the rotor to be slightly slanted when it's installed. either that or the rotor spider wasn't machined very evenly.

has anyone else encountered this issue, or noticed it on their disc rotors?
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Old 04-23-19, 11:01 PM
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are you sure its not just the spacing being slightly different? Hubs have different tolerances even from the same manufacturer combined with possible uneven mounting surface
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Old 04-23-19, 11:06 PM
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I've switched rotors from hub to hub without incident, although sometimes the rotor had to be re- centered when the wheel was on a different bike with a different caliper AIR.
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Old 04-24-19, 10:53 AM
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Perhaps, bent it as you moved it over?


Disc If It's flat I'd just adjust the caliper to the rotor...

loosen bolts, hold brake on , tighten mounting bolts again.






...

Last edited by fietsbob; 04-24-19 at 10:58 AM.
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Old 04-24-19, 05:57 PM
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Originally Posted by spectastic View Post
has anyone else encountered this issue, or noticed it on their disc rotors?
I assume you mean by "rub" that you have some runout with the new setup, and can't adjust the caliper so that it never drags.

If so, then yes, absolutely. Nothing is perfect, right? The rotor face on the hub may not be EXACTLY perpendicular to the axle. If it's not, then a perfectly flat rotor would have some lateral runout as it spins. On the flip side, a rotor itself may not be EXACTLY flat. If it's not, then it'll have some lateral runout even on a perfectly perpendicular hub face. You can clock a rotor in six different positions on a 6-bolt hub. A rotor/hub combination may run perfectly true with the rotor clocked in position 1, but could have some runout clocked in position 3. Of course, switching rotors and hubs can introduce some of this tolerance-stacking, especially if you unknowingly had a nicely-matched pair with one combo and moved to a poorly-matched pair with another combo.

You can re-clock the rotor on the hub to see if that helps. You can also "true" the rotor on the hub (bend it around so that it runs true as installed). If you true the rotor this way, and get it perfect as installed, then it would not be perfect if you re-clock it or move it to another hub.
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Old 04-25-19, 08:52 AM
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My take is that the caliper alignment is not the same on both bikes. It is the caliper that has to be moved over to eliminate the rub. Once the rotor bolts are tightened that is that. Loosen the caliper mounting bolts, lock the brake lever down, re-tighten the caliper bolts. Enjoy.
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Old 05-02-19, 07:53 PM
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it's the same bike
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Old 05-02-19, 08:46 PM
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Originally Posted by spectastic View Post
my hubs are all 6 bolt. when i switch rotors to a different hub, the rotor somehow rubs with the new hub. My theory is the hub disc rotor mount holes weren't machined very precisely, causing the rotor to be slightly slanted when it's installed. either that or the rotor spider wasn't machined very evenly.

has anyone else encountered this issue, or noticed it on their disc rotors?
Rotor spacing varies from hub to hub. Unless these hubs are identical brand, model, and SKU...your choice is to either recenter the caliper ever time you change wheels, or shim rotors with precision shim stock.
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Old 05-03-19, 10:29 AM
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there are die cut shims for 6 bolt hubs/rotors.
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