Had a tire blow off the rim after fixing a routine flat. Saw this:
Upon closer inspection, there were several small dings around the rim. The braking surface was very, very worn. We built this 48H Deep V wheel about 4 years ago. I guess it's a great sign we're riding enough!
I know the black arts so rebuilding to a fresh rim was no big deal.
With higher loads and higher speeds of tandems, this was a good wake-up call to pay close attention to details.