Not the pads on the rim, but the whole assembly. It is loose and rocking around on its spindle, where it is mounted to the frame. I've made a video to help you answer the question! I know it's not clear and I don't have sound on my camera, otherwise I would give a running commentary. I have tried a spanner on the bolt that I point to first, but it doesn't want to to turn. I wonder, do I have to completely remove the nut and bolt that I point to second in order to remove the front caliper so I can get to and tighten the bolt that I point to third? (mostly hidden by the front caliper). See here: http://www.flickr.com/photos/46310695@N02/4522989791/?processed=1&cb=1271345582192 Many thanks!