Thanks Fred, I've had two recent problems with the BB area. Firstly, I had a problem with an irritating tick on each stroke of the pedals a few months ago that I tracked down to the EBB bolts having made a double hole - I had probably been too asiduous with keeping the chain tight. This second and latest problem is definitely more a low level grinding noise that followed the loud clunk and is one I normally associate with a bottom bracket bearing. My problem is that I cannot shift the BB from the eccentric and when I tried to do it while it was still mounted on the bike the whole eccentric turned and the bolts gouged a channel. I just wondered whether anyone had any tips on extracting BBs from eccentrics? I've replaced BBs on a standard frame before but not on an eccentric.