Not all bikes are stolen or sold on Craigslist -- some of them are just abandoned. Yes, it sounds cruel, but I'm sure you've seen at least one bike left to rot on the streets of Denver. What happens to these orphans?
Eventually the city removes them, most often because of a complaint, reports Stateline. Then in Denver, it's off to auction:
"Denver police, for example, auction approximately 120 to 150 bikes every three months, about a third of which are abandoned, said Bart Malpass, a Denver police detective. (The others have been stolen or held by police for other reasons.)
"If the bikes are in bad shape and not rideable, they’re put in groups of five or seven and sold as a lot, sometimes just frames or wheels. Auction proceeds go to the city’s general fund."
But it turns out this is the least exciting way that a city can dispose of abandoned bikes. New York City sends their abandoned bikes to a scrap recycling center and Chicago gives theirs to a nonprofit that donates the bikes to developing countries.
My award for the most interesting disposal method would go to Wichita, Kansas, where the police department’s homeless outreach team can claim abandoned bikes.
Correction: An earlier version of this story misstated the proportion of abandoned bikes that are auctioned off each year. About 150 to 200 abandoned bikes are auctioned each year.
