BARSTOW, CALIF., NOV. 24 -- Ten motorcyclists were arrested today during a tense showdown with federal authorities in Southern California's Mojave Desert over cancellation of this year's venerable Barstow-to-Las Vegas dirt bike race.

More than 100 angry cyclists, declaring themselves defenders of Americans' right to use the nation's public lands, joined in the protest on a wind-swept patch of desert about 110 miles northeast of Los Angeles.

Despite a brief shoving match between a demonstrator and rangers with the U.S. Bureau of Land Management, there were no injuries, authorities said.

Four dirt bikers dressed in colorful racing regalia were arrested after they sped around a phalanx of federal rangers onto land the BLM had temporarily closed in hopes of discouraging an off-road protest ride through environmentally sensitive terrain.

One rider's bike stalled in the sand a short distance away. But the other three were chased about 40 miles across the desert by a San Bernardino County sheriff's helicopter before they ran low on fuel and stopped, BLM District Ranger Felicia Probert said.

The four face up to one year in prison and a $100,000 fine if convicted of violating the BLM's land-closure order. Five other bikers were arrested and cited for similar violations east of Barstow, and a 10th protester was taken into custody after he tried to block an Army tank motoring across the closed lands from nearby Fort Irwin.

"These tanks are doing more damage than a bunch of motorcycles," Louis McKey, 59, yelled before being led away and handcuffed.

Dozens of other demonstrators, meanwhile, mounted their bikes and followed routes around the closed territory without interference from law enforcement officials.

"We came to ride, so we're gonna ride," said Jim Smith of Laguna Hills, Calif., a member of the Racers Under the Sun Christian motorcycle club. "Barstow-to-Vegas is an important event to us. It's a tradition. That's why we're here to make this statement."

The Barstow-to-Vegas race, first run in 1967, is considered the premier amateur dirt bike race in the world, drawing 1,200 riders and thousands of spectators annually. Racers use dry washes, dirt roads and trails to travel the timed course, which stretches up to 150 bone-jarring miles.

Through the years, environmentalists have opposed the event, contending that the dirt bikes irreparably scar the desert and harm its inhabitants.

This year their complaints took on new urgency with the federal government's listing of the desert tortoise as a threatened species. In September, the race's sponsors announced that they were canceling the event because they had lost hope of obtaining a federal permit.

That news sparked rumors of a protest ride. The BLM, fearing that thousands of angry, unmonitored bikers might encroach on sensitive tortoise habitat, declared the traditional race routes and staging areas off-limits to motor vehicles.

In interviews, protesters said that the loss of the race is symbolic to them of a broader peril -- the restriction of off-road vehicle access to the desert.

Many motorcyclists also disputed arguments by scientists and conservationists that off-road vehicles damage the desert and endanger the tortoise. "We're not the bad guys everyone says we are. We love the desert," said Jim Tarrant, 44, a mechanic from El Toro, Calif. "Things may look bad right after a race, but once you get a good windstorm, it's back to normal."