Well, mystery solved. It was the drive chain after all. Needed an MOT, passed again, so got the garage to have a look at it. Apparently, the current chain has several tight spots as well as several very loose spots. That causes it to klick over the front sprocket and slap quite violently against everything it runs over and around. Disappointing, as it is only two years old, has done 5k miles and has got a Scotty on it. The sprockets also got more and less worn teeth. Replace all!
The original chain lasted 32k miles! Only replaced two years ago. What make would that be?
The original chain lasted 32k miles! Only replaced two years ago. What make would that be?