thanks for the replies here. I had a cable brake caliper but it wouldn't lock the back wheel and I was persuaded to get it changed to a hydraulic - which was clearly better and did lock the wheel. however I had to change my combination brake and gear shifter to do so. I'd like to change back to my original combined brake and gear shifter unit but son't want to sacrifice the good braking I have, thats why I was hoping to find a decent cable brake caliper