A group in our sister city to the north is planning to launch a bike-sharing program inspired by Portland's Yellow Bikes, a set of 16 neon green bikes that riders can pick up from bus stops and leave at other bus stops.
The Green Bikes boosters apparently haven't noticed that Portland's yellow bikes are no longer around. The free, brightly-colored bikes placed around the city depended on citizens' good will to share them and call up a mechanic when they broke so, of course, most of the bikes disappeared. Occasionally they are found in the mud on the bottom of the Willamette. So, uh, good luck with those 16 bikes, Seattle.
Having enough bikes is a big deal for bike sharing. The most successful programs have a serious density of bikes (Paris has 10,600, Montreal has 3,000, for example) so that it's super easy to pick up and return bikes across the city. Portland has been looking into starting up a more serious bike sharing program, where bikes would be rentable like Zipcars but the $2.64 million startup cost to put 660 bikes on downtown streets has so far dissuaded the city from jumping in. On the other hand, Washington DC applied for a federal grant to expand its bike sharing program to 1,100 bikes while even Des Moines launched bike sharing stations two weeks ago (though with only 18 bikes).