Volunteers in Winnipeg are spending 24 hours straight turning bikes destined for landfills into refurbished holiday presents for kids in need.

Surrounded by Christmas lights and the sound of metal clanking, volunteers at Valour Community Club on Burnell Street were busy Saturday replacing gears, pumping tires with air and tightening brakes.

They aim to have more than 300 bikes fixed and ready to ride by Sunday at noon.

"It's a herculean effort," said Patrick Krawec, the managing director of the nonprofit WRENCH — the Winnipeg Repair, Education and Cycling Hub — which organizes the 24-hour Cycle of Giving bike-building marathon, now in its seventh year.

"Sometime between the midnight and 6 a.m. shift the magic happens and we always pull it off in the end."

WRENCH worker Pat Neufeld stands in a semi-trailer filled with bikes in need of repair. The bikes were all diverted from Winnipeg landfills. (Laura Glowacki/CBC)

Dozens of volunteers are formed into an assembly line. Each station focuses on repairing a different part of the bicycles.

Laura Donatelli provides the finishing touches — a soapy scrub-down of the bikes. With a green pad in hand, Donatelli scours away every speck of mud and rust.

"It's very gratifying to think that 300 kids will have a bike, which is something I know I treasured in my childhood," she said. This is her second year taking part in Cycle of Giving.

Krawec said his hope is for children to wake up to a gleaming new (or at least new-looking) bicycle this holiday season. They also get to open a handmade card, decorated with images cut from discarded magazines.

While kids benefit from the volunteers' work, for Krawec, the bike-building marathon has both political and environmental implications as well.

Patrick Krawec, Cycle of Giving organizer and managing director of the WRENCH, holds up one of the bikes volunteers will fix up for kids. (Laura Glowacki/CBC)

Thousands of bikes have been diverted from Winnipeg landfills thanks to the event, he said.

"These problems that we're facing — the rampant child poverty, the rampant over-consumption — these are complicated problems," he said.

"But getting together with your community and thinking about it and doing something about it is the only way we're going to solve anything."

Krawec said while Cycle of Giving started as a fundraiser, the need was so great he turned it into the bike drive and giveaway it is today.

The WRENCH is accepting used children's bikes and food to fuel volunteers until Sunday at noon.