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Discussion Starter · #1 ·
Hi, i'm in a bit of a pickle, so my rotor on the rear wheel of my "Specialized Epic Comp 2010" is wobbling around alot (left and right)

At first i thought it was the rotor not being true, however that wasn't true, i switched my front rotor (which is true and perfectly wobble-free) to my rear wheel, and it started wobbling left to right, did some research and found that loose bearings on the freehub could cause that, so i took apart the freehub, re-did the bearings, cleaned it all up, re-greased, new bearings, e.t.c and made sure it was tight, practicaly no play, all perfect, still wobbling...

I noticed my casette is missing it's spacers and the top 3 rings are loose, now i'm gonna replace the casette, i'm just not sure if the casette can cause the rotor to wobble on the bike, another possible theory i have is that the actual wheel isn't true, recently i replaced a spoke on the rear wheel & got it pretty damn good with adjustment, but it could be off, maybe that can cause the rotor to wobble?

What do you guys think it could be, because the wobbling is making my life damn hard, i've got AVID elixir R's on my specialized and they leave VERY limited clearance even when bled right and perfectly setup (i replaced the seals on the rear caliper), i've got the clearance but with the rotor wobbling, it's damned hard to get it not to rub,

any ideas? thanks.
 

· Rippin da fAt
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Since the rotor is directly mounted to the hub, you need to look to the rotor or mounting surface to determine what is going on. Cassette is a separate item, directly mounted to the opposing side of the hub, therefore irrelevant.
Wheel runout is a separate item.

Without being able to get mitts on the bike, diagnosis is difficult.
 

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The wheel's trueness will not impact the rotor's trueness. Only the hub moving could cause this, but if that was the case, you would know it.

It is more likely that the caliper simply isn't aligned properly. Remove the pads, and verify that the caliper is centered over the rotor. Look down from the top and the disc should appear mid-way between the two slides in each of the slots. If it is not, adjust the position of the caliper until it is. Then replace the pads. (You might have to reset the pistons.)

Avid brakes might be worth replacing with anything Shimano makes, however inexpensive.
 

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The wheel's trueness will not impact the rotor's trueness. Only the hub moving could cause this, but if that was the case, you would know it.

It is more likely that the caliper simply isn't aligned properly. Remove the pads, and verify that the caliper is centered over the rotor. Look down from the top and the disc should appear mid-way between the two slides in each of the slots. If it is not, adjust the position of the caliper until it is. Then replace the pads. (You might have to reset the pistons.)

Avid brakes might be worth replacing with anything Shimano makes, however inexpensive.
I would also recommend checking for possible axel play. By the way what brand of hub is it?
 

· Rippin da fAt
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Hub shell bent to hell, rotor bent to hell or improperly seated on the hub or all of that...
Bent axle and cassette and rotor are off axis but not wobbling about.
 

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Discussion Starter · #7 · (Edited)
The wheel's trueness will not impact the rotor's trueness. Only the hub moving could cause this, but if that was the case, you would know it.

It is more likely that the caliper simply isn't aligned properly. Remove the pads, and verify that the caliper is centered over the rotor. Look down from the top and the disc should appear mid-way between the two slides in each of the slots. If it is not, adjust the position of the caliper until it is. Then replace the pads. (You might have to reset the pistons.)

Avid brakes might be worth replacing with anything Shimano makes, however inexpensive.
(my rear wheel)

(my front wheel)

64950009918__998CF460-390E-4249-B214-B62EDE6001C3.MOV (rear wheel again)

Top video is my rear, middle is of my front, bottom is rear (with my front's rotor on it)
 

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Well that's weird, never seen anything like that.

With the wheel fitted is there any play or wobble if you try and move the wheel side to side?

Is there any damage to the area the disk bolts too?
 

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Discussion Starter · #9 ·
Well that's weird, never seen anything like that.

With the wheel fitted is there any play or wobble if you try and move the wheel side to side?

Is there any damage to the area the disk bolts too?
No play with the wheel fitted, made sure to get that sweetspot when tightening, nice and smooth yet no play,

Can't see any damage to the disk bolts area, i had a deep look, tightened the rotor up perfectly and tightened the QR skewer when putting the rear wheel back on, still wobbles, to the left only now...

my theory is the QR skewer just isn't tight enough, therefore the rotor wobbles, as the skewer on my front is a different one and can be tightened hard with a wrench
 

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Discussion Starter · #11 ·
Check that the rear wheel is sitting correctly in the frame. If for some reason it isnt that could also cause your problem.

Switched the rotor to a spare 180mm, and took a video of the wobble, identical to my 160mm, both deviate left, also watched the plastic hub that attaches to the rotor WITHOUT the rotor on it and put a hole through white paper on the ground, it was deviating left, i don't think this is rotor related or QR SKEWER related as i swapped the rear skewer with a spare and same result

however the hub seems in good condition, makes no sense
 

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Discussion Starter · #12 ·
Update : I thought it was the mounting plate (where you mount the rotor to the hub) that wasn't perfectly flat, therefore wobbling any rotor on there, but not so sure anymore, besides replacing that would involve rebuilding the entire wheel or buying a new one or best case sanding it down to be flat, besides

I went ahead and took my brothers bike's rear tire off (specialized epic as well), popped it on mine with his own rotor on that wheel and had a look, wobble still exists!, also tried it on his bike and on my spare black bike and same issue, wobble of some degree on the rear, left or right,

So i can only summarize that it's seemingly normal for the rotor to move left and right, also had a look at my front again and it does move left and right, just a hell of a lot less, must be alot more true,

Reason i was trying to fix it and have the rotor be perfectly still and not move left and right is because i've got avid elixir r's, the clearance is a god-damn hell nightmare to get right, and with the rotor wobbling left and right, makes it harder to get that rub gone,

Can anyone please VERIFY that it's normal for the rotor to wobble left and right, even when basically trued, as i've got three bikes doing the same thing on the REAR & unless the mounting plates for the rotor to screw down on all aren't flat then it's got to be normal / rotors not being true,

TL;DR ; this is annoying, and avid clearance is the worst.
 

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You dropouts must be bent. It is the only thing that explains it. If so then the wheel itself should appear to wobble also. Actually I’m not sure that makes sense so never mind.
 

· Rippin da fAt
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Update : I thought it was the mounting plate (where you mount the rotor to the hub) that wasn't perfectly flat, therefore wobbling any rotor on there, but not so sure anymore, besides replacing that would involve rebuilding the entire wheel or buying a new one or best case sanding it down to be flat, besides

I went ahead and took my brothers bike's rear tire off (specialized epic as well), popped it on mine with his own rotor on that wheel and had a look, wobble still exists!, also tried it on his bike and on my spare black bike and same issue, wobble of some degree on the rear, left or right,

So i can only summarize that it's seemingly normal for the rotor to move left and right, also had a look at my front again and it does move left and right, just a hell of a lot less, must be alot more true,

Reason i was trying to fix it and have the rotor be perfectly still and not move left and right is because i've got avid elixir r's, the clearance is a god-damn hell nightmare to get right, and with the rotor wobbling left and right, makes it harder to get that rub gone,

Can anyone please VERIFY that it's normal for the rotor to wobble left and right, even when basically trued, as i've got three bikes doing the same thing on the REAR & unless the mounting plates for the rotor to screw down on all aren't flat then it's got to be normal / rotors not being true,

TL;DR ; this is annoying, and avid clearance is the worst.
true the rotor to within.002".
 

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The tire and wheel rim have nothing to do with it, ipso facto. If the issue persists when you switch in a different wheel, that tells you it is not the wheel.

If the issue follows the wheel to a different bike, then it must be the wheel.

I am having a hard time following what is going on, whether you are changing wheels or tires, or using tire interchangeably with wheel.

Assuming that the wobble persists when you put a different wheel in the bike frame in question, that leaves you with two options: (a) The brake caliper is misaligned, which is an easy fix, or (b) the frame dropouts are misaligned, or the frame has some other damage, which is not an easy fix.

Assuming the wobble does not persist when you change the wheel, it is probably time for a new wheel.
 
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