Why does my rear brake want to rotate and rub?

[Disastrous]

The read brake on my Specialized Allez has started trying to rotate itself on its fixing bolt to cause the left pad to rub the rim.

I appreciate the the cable outs it under a degree of tension and if the central Allen bolt isn't tight, it will rotate but I've tightened up as hard as I dare and yet when I come back to it a couple of days later, it seems to have moved again.

In terms of changes, the only thing I've done lately is buy a Tacx TT and change the QR skewer to their one. Culd the TT riding be somehow responsible??

Puzzled...

[mk1fan]

You need to adjust the spring that keeps the caliper apart. There will be a grub screw on the top of the caliper.

Or you need a longer cable outer.

A quick chat with your LBS during a quiet time in the shop (not a weekend, lunchtime or after work) and I'm sure they will be happy to explain what you need to do.

Or You Tube.

[Disastrous]

Will pop in and check next time I'm out.

Seems odd that it would suddenly start doing it though after being fine for years, doesn't it? Or is that normal?

[snotrag]

Sure the wheels in straight?