I have an xc HT that has X0 brakes on c/l avid discs. They look like a normal g3 disc on the brake track, but them they are rivetted to an alloy central carrier that allows them to be centrelock.

Todays clean and maintenance has revealed that the rear disc has some rotational play, but its not detectable radially. The front doesnt do it. How acceptable is this? Its not a floating disc, just two piece.

Not exactly the same, but I had some Clarks floating rotors on a bike and after a years use I started noticing some rotational play. I kept note and carried on riding. It was fine for another 6 months before the play go too much for me and I swapped them. This was on an Enduro bike.

It will have some movement if it is a floating disc…as it heats up it stops moving as it expands slightly…I’m pretty sure my Hope floating rotors did that.

Just re-read your post and it isn’t a floating disc…so my comment is junk.

Ok…it seems i tolerate until i get scared!

Give the rivet a smack with the hammer, did it to my hope rotor,not rattled since. Used a socket to support back of rivet.

There shouldn’t be any movement. Had it happen on a Hope floating rotor and sent it back, they repressed the bobbin.

I really don’t like rattles, squeaks or rubs on my bikes.

I don’t think a rotor like you’re describing should have ANY play in them. They’re not trying to float like a Hope rotor, it should be a solid mechanical join.