I confess to not keeping up with the maintenance sometimes on the bikes. I pick the one that's working best and ride it. Sometimes I even ignore obvious problems until things go fully south on me.
So, the Big Dummy hasn't been shifting so well lately. I've ridden it anyway. It's perfect for what I need to do around town getting groceries and hauling things like The Boy. Finally, I went to fetch 'er up in the garage and noticed a flat rear tire, so I picked a different bike that day - and the next. Two weeks go by and I really need the Dummy for some projects, so I haul it down to the basement to give it the once-over. I figured out why it was shifting poorly.
Yeah, there's a big chunk missing from the 25 tooth cog. Can't say I saw that coming.
So, I threw the chain into the spokes a few times and had to pull it out like He-Man. I'm a dork. I think this might once have been a proud Dura-Ace 12-27 cassette. I have no idea why I ran it on the Dummy, but there it was. Moral 1: don't use the light bits on your cargo bike. Once I removed the debilitated cassette (whose lockring was decidedly loose - moral 2: keep the bits tight) I saw the rest of the damage.
Yeah, the spokes were all banjaxed and the wheel needs to be rebuilt. I may even have to retire that boss XT hub. Moral 3: shifting the chain into the spokes once is reason enough to have a look under the hood.
The overarching moral: I'm an ass.
Carry on with your day - and check your bolts before you go home.