After hedging about whether the city’s long-awaited bike-share program would begin as scheduled this month, city officials acknowledged this week that its start would be delayed for some time, without explaining why.

On Thursday, however, Mayor Michael R. Bloomberg offered a culprit: computer problems.

“Its software isn’t working yet,” he told reporters at a groundbreaking ceremony in West Harlem. “And just rest assured we’re not going to put out any program here that doesn’t work.”

It remains unclear when the bike-share program, Citi Bike, will begin; last week, the program seemed to tip the city’s hand when someone manning its Twitter account wrote that the program would begin in August.

City officials have said only that they are finalizing details of the start of the program, which by next summer is expected to include 10,000 bicycles at 600 stations, each equipped with a kiosk featuring a touch-screen monitor.

Mr. Bloomberg said there was no reason to be concerned by the delay.

“There’s no government money involved whatsoever here,” he said. “The only thing about a delay — if it turns out that there is one — is that people won’t be able to use something that we think will be phenomenally popular. But until we get it working perfectly, have these private companies do it to our satisfaction, we’re just not going to put it out.”

The mayor also seemed amused by the consternation over the program’s start date.

“What’s fascinating,” he said, “is there was a lot of screaming, ‘We don’t want bikes,’ and now everybody’s screaming, ‘We want ’em now.’”