How will bixi deal with commuter hoarding once it extends just beyond downtown? I foresee hundreds of students and downtown office workers renting bikes first thing in the morning, riding them to universities and the downtown core where they will sit empty for most of the day, then taking those same bikes back to the fringe areas in the evening. During the day, there could be too few bikes in fringe areas, and more bikes than there are docking stations downtown. What do you do if you try to return a bike, but all of the racks in the nearest 10 blocks are full?
From a logistical perspective, what makes car sharing possible is that you rent and return the car to the same lot. Bixi may seriously have to employ a team of full time cyclists to ensure that bikes are well distributed throughout the city at all times of the day.