Challenge-seeking mountain bike racers annually flock to the Downieville Classic, a lung-searing, bone-rattling, 29-mile ride from Sierra City to Downieville over the Sierra buttes.

This weekend, in the 17th running of the cross- country and downhill races, participants will find the course more challenging than usual – gnarly and epic, to quote the sport's idiom.

Record snowfall, followed by a brief January thaw, followed by more late- season snowfall, rendered the course almost unrecognizable, said Greg Williams, race founder and executive director of the Sierra Buttes Trail Stewardship.

In the past month, volunteers have been scrambling to dig out from snowdrifts as high as 20 feet in some sections of the dirt trail, and solid ice 6 feet deep on the paved sections. There was talk that the race, which attracts mountain bikers from around the world, would have to be canceled.

But near round-the-clock trail maintenance and snow removal, made possible by $10,000 in funding from the Sierra County supervisors, $15,000 from the Sierra Buttes Trail Stewardship and $1,500 from sponsor Clif Bar, has enabled crews to to carve out a semblance of the original course.

Instead of 29 miles, participants will traverse "only" 23 – but the infamous "Trail of Tears," eight miles uphill at the start, remains.

"There will be spots where riders will basically be going through snow tunnels 10 feet deep," Williams said. "And there will be spots they'll be (riding) over the snow. But this is what makes it epic. This'll be one of those years nobody forgets about. All the years it's smooth and the weather's great, you never remember those.

"In 17 years, I've never seen anything like this. I've never seen this much snow this late."

Williams said the economies of Sierra City and Downieville have been hurt because the mountain- biking trails – some of the best in the state – were closed during all of June.

"That's 20 percent of the business for the motels and restaurants," Williams said. "There's been an outpouring of support. Getting (the trails) open has banded the community together."

If there's one thing more difficult than competing in the Downieville Classic, Williams said, it's getting the course in shape to hold the event.

"The county lets us use their (snow) blower, built in the 1940s," he said. "In the first 15 minutes of bringing it up there, the blower sucked in a red fir tree that had fallen across the road and was buried in the snow. It's taken several weeks to make progress."

Snow was not the only obstacle, Williams said.

"We've been removing a lot of deadfall," he said. "And there was so much water channeling down the trails – super heavy-duty erosion. Our crews have been rebuilding the drainage and offsloping the tread so that the water doesn't run down the middle of the trail."

The course had to be further altered because a normally placid, foot-deep stream crossing now is a 5-foot-deep raging river.

"We could see somebody get in there and cramping and down the river they go," Williams said. "We don't want anybody to die."

DOWNIEVILLE CLASSIC

The Downieville Classic Mountain Bike Race and Festival runs Friday through Sunday in the Sierra County town. Included will be a 23-mile cross-country bike race and the 17-mile downhill race. The river jumping race has been canceled because of high water from snow runoff.

Registration will be available Friday from 3-7 p.m. in Downieville at the Community Hall and on Saturday in Sierra City at the Community Hall. More information: www.downievilleclassic.com.

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