I moved away from Portland a couple years ago. At a recent protest in my new city, I saw a dude riding a 10-foot-high tall bike and realized I hadn't seen one in Portland since like 2008. What happened? Where did all the tall bikes go? —Tucker J.

When complaining about your city's decline, it's often a good idea to stop for a minute and make sure the decline you're bemoaning is really the city's and not, you know, yours: "Remember when Portland was cool? When it was easy to have a bowel movement, and you never had to cut holes in your sneakers so your bunions could stick out? Good times."

Given this, I won't say for sure that the changes that doomed Portland's tall bikes are the same ones that made me have to put tennis balls on the feet of my walker. I can say, however, that they're pretty much the same changes we've been complaining about in various other contexts around here for the past 15 years.

For those fresh out of the monastery, a "tall bike" is a home-welded contraption where two (or more) bicycles are welded on top of each other to make one exquisitely dangerous conveyance. Favored by indestructible young people who enjoy falling off skateboards onto concrete stairs, tall bikes are the personal transportation equivalent of shotgunning a PBR.

As Tucker implies, there was a time when these home-welded rolling death traps dominated every Critical Mass event and Naked Bike Ride in the Rose City. Tall bike aficionados staged Olympic-type events where riders would joust, race and otherwise maim themselves for the benefit of delighted onlookers.

What happened? Portland's housing costs went bonkers. Suddenly, those big, cheap houses, with their welding-friendly basements and ample garages, were out of reach for most of those indestructible young people. Meanwhile, the same rising cost of living made it harder to survive on those part-time jobs that used to give kids plenty of free time for street art/self-maiming.

Tall bikes are still around, though. Birmingham, Alabama, mounted its seventh annual bike joust last year, and there appears to be a tall bike scene in still-cool Detroit. I bet those kids never break their hip getting out of the shower.