Originally Posted by jnbrown
The slipping pawl does make some sense but if that was the case I would think I would feel the slip in the crank and I don't think I do.
I had a rear freewheel go out recently (on a single-bike, not a tandem). It started making clacking and pinging noises when I started pedaling - especially if I engaged the pedals lightly. I never felt a slip in the drivetrain - just heard the pinging/clacking noise. I talked to my LBS mechanic about it, and he said that it's normal to not feel slipage because there are a couple of pawls in the freehub - and if one lets go there is a noise, but no slipping, because the other pawl is still engaged. He said that the freewheel probably wasn't fully engaging because of the cold weather, and told me not to worry about it.
Well, two weeks went by, and then the freewheel totally let go in a sprint. I fell down, messed up my shoes and scratched my right pedal and brifter. I was OK though... Following that incident, I had the freehub rebuilt.
I believe this noise is something to be concerned about. I would get it looked at.