Glazed disc?

[jonzi]

Is this a glazed disc?

http://i.imgur.com/tIrJUYL.jpg

If it is what can I do about it?

if it ain't, then what is it?

When I push the bike the brake is dragging. It's the rear. Never used. But I have had problems with it in the past

[garry]

yes mate, looks like its dragging, time to service the caliper...

[Tosh]

Aye, I agree with Garry. Caliper dragging causing heat to blue the disk . As long as the disk hasn't warped, just service the caliper and the disk will clean up with normal use.

[Darren69]

As others say, its burnt. Check as it maybe warped.

[Dukedesmo]

I had this happen to my 916 rear disc, caliper stuck on and it got tighter & tighter until it eventually seized up completely, at which point the pads were on fire and all the gold paint around the edge of the disc burnt off.

Disc was well blue but worked fine (well, as fine as a 916 rear brake ever can) afterwards...

[utopia]

Grab hold of the brake cylinder actuating rod and jiggle it around (with the lever at rest, obviously) to feel for free play (when cold).
There should be a noticeable amount.
Check it again when everything's heated up and see if the free play is still there ..and adjust if there's none.
Any air/moisture in the system will expend when hot, taking up the free play and then causing the disc to bind.
Rear wheels have been reported to have "locked solid" ...on the motorway !