Originally Posted by
bulldog1935
science fiction notwithstanding, it's called
filiform corrosion
It's how corrosion progresses under organic coatings and has has nothing to do with microbial-influenced corrosion.
I''m a licensed, professional metallurgist and corrosion engineer.
Fantastic info. Not as sexy a title as rust spiders . . .
Chas, thanks for the info about this being seen in 1980s bikes, which of course fits in this case. Overall it sounds like it's just more cosmetic damage (after repair) to an already cosmetically challenged bike.