Rotational movement on centre lock disc brakes - normal?

SitoUK

HI there

I have a brand new set of wheels with centre lock brake discs (1 week old). When I went to work this morning I noticed the following on both wheels: Even when you completely lock the brake, there is still some rotational movement on the wheel. The disc does not move but the wheel does, maybe a couple of mm at the outer edge or so.

Is this something I need to be concerned about or is it normal? Has anyone noticed the same thing? It certainly never happened with my 6-bolt wheels.

Cheers

Lars

myopic

probably the pads moving in the calipers?

SitoUK

no, definitely not. The disc does not move, there is some movement at the link between disc and wheel. I have the bike on a a bike stand now and you can move the wheel slightly by hand when pulling the brake but it requires a bit of strength.

SitoUK

Hmm, just found this: http://forums.mtbr.com/showthread.php?t=581436

The guy says it was a tighness issue. Might be the same thing in my case...as I don't own the tools the dics were mounted onto the wheel by my LBS...might have to give them a call...

mrfmilo

Don't know much about centrelock but if it's moving forwards and backwards, worn splines?

SitoUK

might be the case...on the other hand...wheels are only a week old, 100km max on road use, so I would not expect this much wear. I get the impression though that this is not the norm, so I guess a visit to the LBS is due...

mrfmilo

If they weren't tightened properly from the start, so that there's movement in them, they may have worn them - I may be completely wrong though

SitoUK

possible...I should find out tomorrow morning and will let you know what the story is...

XCMark

I had this with some shimano rotors a while back, it was the rivets holding the braking surface to the spider that turned out to be worn.

PXR5

I've seen exactly the same "problem" when i recently changed to Centrelocks, I think its probably just very slight pad movement, couple of mm movement maximum on the outside of the tyre - I've posted previously about the front brake juddering under load and wondered if these things were linked, but i'm pretty sure now that the unwanted ABS type effect was incompatability between the Juicy 3s and the change between the standard CleanSweep2 discs and the Shimano Centrelocks, the outside diameter of both is 160mm, but the inside is less, in other words the brake pad was also rubbing against the spokes on the Shimano disc as its got less surface area than the CS2..if that makes sense...

SitoUK

hmm, interesting, I did the same thing. I've got Juice Threes and changed the original discs to Shimano discs.

However, I think we're describing slightly different scenarios here. As I said, my disc is not moving at all, it's held absolutely tightly by the brake pads. Only the wheel is moving. So the movement is not between brake pad and disc but between disc and hub.

Chunkers1980

So it's what XCMark says?

That's the trouble with bonded rotors.

SitoUK

well, but you would not expect this to happen after a week I assume....

Chunkers1980

no - they must be faulty if they have not taken any hits.

SitoUK

yes, that's what I suspect as well...I called the guys and they'll take it apart tomorrow morning....I just hope I make it home tonight and there tomorrow morning safely :?

supersonic

The tool for the rotors is just a standard cassette tool, or in some cases, a BB tool.

SitoUK

ah, interesting, did not know that. Thanks, that should disc exchange make easier in the future..

SitoUK

ok, just an update: went to eh LBS today and he simply tightened the center lock a bit more. He used quite some force to do that. So that was it, it's all fine now. Good to know for the future....

lesz42

the spines on XT hubs can and do, "open" up, and the rivets , holding the disc to the "center-lock" get loose


theres more mechanical joins on a center-lock rotor, more to go wrong?



tweek cycles pointed out the play in my front rotor, between the rotor and the center-lock bit