My chain has been making some funny noises, finally had a look at it. Found the slack was way off, so i fixed that. Then i go to turn the wheel. As far as i can tell, the joiner link is slightly longer than the other ones, and thus sits funny on the sprockets. So when the wheel turns, the tension of the chain changes between tight and floppy. I guess thats the noise ive been hearing. I've had a look at the joiner piece, it doesnt seem very adjustable. I fear my chain is fuxored. Time for new chain and sprockets you think?