Hard to believe it’s only been two years since bike-share launched in New York. After a tumultuous start roiled by software bugs and the bankruptcy of a key supplier, the city’s bike-share system is finally on a more even keel and ready to expand. Today NYC DOT and Citi Bike announced a firm date when the next batch of stations will begin to roll out: August 10.

The expansion zones will be getting 139 new bike-share stations this year, the first phase in what will add up to at least 375 new stations by the end of 2017. Right now the system has 332 stations, so it’s about to grow 40 percent.

Here are the numbers from Citi Bike about which neighborhoods are getting how many stations in 2015:

• Queens: Long Island City, 12 stations
• Brooklyn: Bed Stuy, Williamsburg, Greenpoint, 79 new stations
• Manhattan: Upper East and West Sides to 86th Street, 48 new stations

One fly in the ointment — and it’s a big one — NYC DOT is planning to spread out the new stations too thinly. If DOT and Motivate don’t figure out a plan to maintain a sufficient density of stations as the system grows, bike-share won’t be as reliable as it should be in the expansion zones, and that will spell trouble for the whole system.

Hopefully DOT will work out a better plan, because the growth of bike-share is great news, and the system needs to stay reliable to keep on growing.