The bikes' owners so deface them in order to make them less appealing to would-be thieves.
However, some argue that it can have exactly the opposite effect: Crooks, they say, know that the bike must be good if someone made such an effort to make them visually unappetizing.
In any event, the bike in the photo turned out to be, on closer inspection, just a typical '70's Bike Boom ten-speed turned into a single-speed. It's perfectly reliable transportation, I'm sure, but nothing special. Or, at least, it's not special enough that its owner had to make it seem less special.
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