Sadly, it wouldn't clonk while being filmed! It's probably female!
Hmmm... wonder if what we need is some transducer sensors wired into a logging device. Attach transducers to BB, clutch assembly, Centa housing, and compare the results on an acceleration clank. Biggest and earliest jump in the sensor indicates the source*. Anyone know any Uni Engineering departments?
* there can't be many options: Centa, clutch, BB, belt, wheel/suspension. Phil's chain drive removes the belt but its possible there are more than 1 clunk sources...
