All hands were on deck Wednesday at the World Trade Center where 450 volunteers assembled donated bicycles that will be given to children of military families who are on active duty.

All 500 bikes Wednesday were built by employees of companies, first responders and families who were impacted by the September 11th terrorist attacks. The bikes were assembled by teams of volunteers inside the cavernous interior of the white Oculus where commuters and tourists stopped to observe the human team effort, which commemorated the National Day of Service and Remembrance.

“I signed up for both shifts,” said Mark Ramdas, 51, an employee at Bank of New York Mellon whose team of three put a bike together in 15 minutes. “It’s for the kids and it’s a great team building effort.”

Assembled bikes of silver, blue, white and pink, some with baskets and others with rainbow colored ribbons attached to handlebars, were stored in an eighteen-wheeler truck that will deliver them to the children at Fort Bragg Army base in North Carolina on Saturday. Each bike has a personal note written by the volunteers, thanking the families for their military service.

Loved ones lost in the September 11th attacks, as well as survivors, were remembered at the event, which was organized by the 9/11 Tribute Museum. The national day of service remembers September 11th and honors those affected by it through volunteer service.

This is the fourth year Zurich insurance employees Jim Littlefield, 55, of Brooklyn, and Paul Fauty, 52, of Floral Park, volunteered to build bicycles.

“It’s a great cause and actually a lot fun,” said Fauty.

“People are saying hello, and we are getting pats on the back,” said Littlefield, whose mother and brother both escaped the burning towers in 2001. “They live everyday with what they experienced and saw that day.”

The gift of bicycles is a gesture of gratitude to military families, Littlefield said.

“We want to let the kids know that we really appreciate their parents and the service they give to our country,” he added.

NYPD Commissioner James O’Neill and FDNY Commissioner Daniel Nigro also lent a hand by screwing on training wheels, handlebars and writing personal notes to the children receiving bikes decorated with glittery pink, blue, silver and yellow ribbons.

“This is a great opportunity to give back,” said O’Neill, as he attached a tire to a bike frame.

“I’ve got a 28-year-old and a 24-year-old, so I had a lot experience even though it was a long time ago,” said O’Neill, who helped build two bikes.

“It’s about giving back,” said Nigro. “The 9/11 Tribute Museum is a great organization to remember the spirit of 9/11 when people came together.”

Correction: An earlier version of this story misidentified Zurich employee Jim Littlefield.