Minnesotans donated a record-shattering 9,000 used bicycles to the nonprofit Free Bikes 4 Kidz, nearly doubling their previous world record in one busy morning of giving.

"There will be many kids with a surprise bike under their tree this Christmas," said Terry Esau, founder of Free Bikes for Kids.

Donors dropped off the bikes at more than 50 Allina Health locations during a four-hour window on Oct. 7. The overwhelming response broke the Minnesota-based charity's previous record of 5,512 bikes, collected in one day in 2015 and listed with Guinness World Records.

An army of volunteers will now be enlisted to clean, sort and repair the bikes, being kept in a New Hope warehouse, so they'll be ready to distribute in time for the holidays.

"We take volunteers of all skills levels, but we especially need people who know how to sling a wrench," Esau said. "We think we will need 25,000 volunteer hours to get this done."

Esau, a Minneapolis composer and cyclist, started the nonprofit in 2008. It began with his cycling group fixing and donating 250 old bikes. The charity's mission, he said, is creating happy, healthy kids.

"It's that first ticket to explore the world," Esau said.

To date, Free Bikes 4 Kidz has given away 38,000 bikes, mostly in Minnesota. The nonprofit has expanded to Atlanta, Salt Lake City, Portland and Eugene, Ore., and Madison, Wis.

It's a lean operation, with an annual budget of $250,000, and relies on donated warehouse space, volunteer labor and hand-me-down bikes. It has two full-time staffers, including Esau, and does all its collecting and fixing in Minnesota during the same eight-week window — October through December — to keep costs down.

Nothing goes to waste. Bikes too broken to be fixed are harvested for parts and then sold for scrap metal. "We call them organ donors," Esau said.

Free Bikes 4 Kidz relies on community nonprofit partners and schools to help distribute the bikes.

To volunteer, go to fb4k.org/volunteer. Volunteer shifts run three hours.