from www.azcentral.com
(this was a program in downtown Phoenix)

The purple bikes
It was such a European concept. In 1997, the thought was to park bicycles at recognizable purple bike racks around the city. Residents could borrow a bike to get where they needed to go, then leave it at another purple bike rack. Worries that people would steal the Purple People Movers, as the bikes were called, were dismissed. "You can't really steal something that is free," a transportation official was quoted as saying. Somebody figured out how. The program started in April. By May, none of the 60 bikes placed around downtown Phoenix could be found. The bike racks were eventually yanked out, or repainted to match downtown's new branding concept, Copper Square. One lone purple bike rack remains outside the Maricopa County government complex. Anyone who still has a purple bike may return it there if they choose.