I got off and looked at the back tire.
It was detached from the rim.
At first I thought it must have blown out, because I don't know any way for the tire to detach from the wheel rim without destroying it and/or the use of tools. But no: the outer tire was intact. The inner tube was still inflated, albeit at extremely low pressure.
Well, this is an exciting new failure mode I've never experienced before. Guess I'll walk to work and deal with this later, I thought.
Then I remembered I have a dentist appointment today. That I planned to get to via bicycle.
Okay, fine, I will futz with the bike now. It looks like I just need to change the tire, without the actual "change tire" part, anyway.
I wrestled the rear tire off, checked it for damage, and tried to pump it up. This is when I noticed that the air pressure gauge on my 3-month-old foot pump was reading way too low. Maybe this explains why the back tire was low? I pumped it until the gauge read 120, took it off, checked with my $4 pressure guage: 35. It's supposed to be 65. I tried again. On the third try, the foot pump said it was at 60 when I stopped, and so did my hand gauge. Okay then.
I tried to wrestle the wheel back onto the bike. At the bike shop, the owner has a stand he sets the bike on to hold it off the ground while he works on it. If you have one of these, getting tires on and off is easy because you don't have to try to keep the bike up right while simultaneously threading the chain through the gears and the wheel through the brake pads and also the axel through the notches on both sides of the frame.
If you don't have a stand, it's very annoying.
Eventually, I got the wheel most of the way on, and then the axel fell out.
Cue hysterical laughter and/or sobbing.
I put the bike assembly down and picked up the axel.
It was slightly curved.
Maybe it's supposed to be that way, I thought, hysterically. I tried to make it work.
It is not supposed to be that way.
After fiddling with it, I noticed that one of the assemblies on the side of the axel had also fallen off, and there were two greasy ball bearings that I have zero idea how to involve.
I gave up, put everything in the garage to take to the bike shop the next time I have a rental car, washed off my hands, and set off for work.
Halfway up the hill, I realized I hadn't brought my purse, because I don't normally bring my purse to work. But I'd need it to pay for the bus to the dentist. And also to pay the dentist.
So that was my morning. I hope it's going better for everyone else. x_x