OK, so this is what I've eliminated as the cause of the rubbing:

Bent disk – have tried different and brand new disks and also put said disks on a different wheel. On the different wheel, no rub.

OK, looking like something to do with the wheel then. I've stripped, reassembled, stripped again, reassembled again etc the rear hub (a Hope Sport). I've even treated the hub to a new axle and new bearings.

When I look down at the disc in the calliper I can see it is really weaving and warping in and out. With a closer look the flange with the disc bolt mounts is not rotating true, so I guess the disc doesn't stand a chance.

Before I resort to giving up and letting the LBS have a go, any ideas out there?

is the callliper bolted on straight? loosen bolts, squeeze lever and tighten bolts.

ANY CHANCE YOU HAVE PUT THE WHEEL IN THE QUICK RELEASE SLOTS IN LINE?? YOU PUTTING THE WHEEL ON WITH THE BIKE UPSIDE DOWN TO MAKE SURE IT SITS IN THE SLOTS TRUE?? IS THE ROTOR ON THE HUB TRUE, ANY METAL CHARDS STOPPING IT MOUNTING FLUSH?? ONLY THING I CAN THINK OF. GOOD LUCK

if the flange the disc mounts on does not run true than the disc never will. Something badly wrong if that is the case. Disintegrated bearings or bearings not in straight?

Hope.

Contact them and send it in. No-one i know has had bad dealings with them. Assuming you are sure about the hub being the problem.

Has it ever run true? If you've replaced the bearings and axle then it has to be the hub body. Disk flange not machined properly in the factory (if it's never worked right) or bent/twisted in some manner.

If the axle and bearings are fitted correctly then the hub itself must be out of true.
damn, too slow

If the disk runs true on another hub it would appear that the hub is the problem. If you lie a straight edge on the disc is there any gaps? If so try to undo a bolt that corresponds to a gap. Does the gap disappear once the bolt is loose? If so you could try shimming out the low spots so the mounting bolts don't distort the rotor (as much). you'll probably then need to realign the caliper to the new rotor position.

This is only a guess but I think worth a look. Something about the hub is inducing the warpage. It does suggest to me that there is a +/- variance in the rotor seat datum of the hub.

That's a good suggestion, I was thinking more of an angular error rather than low 'spots'.

If that suggestion doesn't work, stick an old spoke or similar to one of the stay's with Blu Tack, just touching the flange. Spin the wheel slowly and see if any gaps appear, or the spoke is pushed out of the way. To do it properly you'd need a dial test indicator, (DTI) if you know someone in an engineering/maintenance job they'd prob be able to put their hand on one.

It used to run true, or at least the original disc was warped in the opposite direction to the hub flange to make it appear true.

The dropouts are Whyte "Big Grippers" so it's pretty difficult – if not impossible – to not get the wheel sat properly.

My thoughts were on worn bearings on badly assembled hub, but having stripped and reassembled so many times now (with new bearings) I can't see how doing it again will help (what did Einstein say about doing the same thing over and over and expecting different results??)

The only other "new" thing that seems to correspond with the problem getting worse was that I had a new wheel built last year on the same hub. The timing could be coincidental, but maybe taking it back to the wheel builders is an idea.

Thanks for the suggestions. It sounds like any fix is beyond my capabilities now…apart from perhaps some shims