The Bloomberg administration is only months away from rolling out an ambitious bike-share program intended eventually to rival ones in London, Paris and Washington, yet the proposal has already been plagued by questions of its viability.

Community board members have raised concerns about whether bike-share kiosks and racks would encroach on precious sidewalk areas, or swallow parking spaces. Some of the more seasoned bike-share companies did not bid on the project.

And the equipment provider for Alta Bicycle Share, one of the two finalists vying to run the operation, has run into financial problems in Montreal. Government officials there eventually provided $108 million in financing to that provider, Public Bike System Company, in part to cover losses incurred by Bixi, the city’s bike-share program.

All things considered, it has been somewhat of a bumpy start for a program that could help shape Mayor Michael R. Bloomberg’s legacy of leaving a more environmentally friendly city.