Of late I have been noticing a nice scratching noise from the rear brake caliper and today i finally got around to taking a look at it after about a week of riding. As i was taking the caliper off i noticed one of the pistons was fully extended and had seized. Which i assume has been the scratching. Here is the state of the pads when i got them out. http://i.imgur.com/bcyUp.jpg http://i.imgur.com/9MRWq.jpg I thought this was a pretty bad case so I mentioned it when i went and got new pads from shop and he pulled out a disk which was knife thin, which i don't understand how the blokes bike was stopping with a disk like that.