Originally Posted by
sapporoguy
We had an infuriating noise that sounds a lot like this, which seemed to be coming from the back. I'd replaced stoker BB so sure wasn't that and had spun the pilot's cranks without chain and it spun freely with no play. I did just about everything possible--pedals, skewers, whatnot.
Then I took off the front crank and spun the righthand bb bearing with a finger--too tight! And there signs it was so tight the shaft was sometimes slipping inside the bearing race under certain conditions. replaced front BB and noise was gone.
Interesting. I think the BBs/eccentric are where we will start our next round of investigation. I am fairly convinced that it is something in that vicinity as so many other bits have been checked, changed, lubed, etc.