Downieville, Calif.

Rocks. Roots. Butterflies. Face plant.

It all happens in slow motion as I fly over my handlebars for the third time while riding over 17 miles of fire roads and rocky, single-track trails that drop more than 5,000 feet in the northern Sierra.

Riding a full suspension bike, I was squeezing hard on the disc brakes to maneuver through a patch of gravel near a rocky rivulet when my front tire slid to the right, sending me plummeting to the ground, where I landed hard on my left knee and hip. I threw up a cloud of dust and a shower of expletives.

How did this happen? Were my eyes drawn off the path by a waterfall, a green meadow or an alpine lake? It's easy to be distracted on these trails, but as you skirt past 300-foot sheer drop-offs, that's a sure road to ruin.

I'm in Downieville, about 100 miles northeast of Sacramento, to test the downhill runs that gear heads and biking daredevils rate as some of the state's fastest and most challenging. As a weekend mountain biker and lifelong Californian, I heard all the talk about Moab, Utah, being the ultimate off-road biking destination. I wanted to find a new biking hub that has the respect of veteran riders without Moab's crowds and hype.

After that third wipeout, I dust myself off, pick bits of gravel from my bloody knee and roll cautiously toward the base of the mountain. As I coast into town, I know I'm not done yet.

BIKERS BLOW INTO TOWN

All is quiet on Main Street on a late-summer afternoon, except for the whisper of rushing water from the Yuba and Downie rivers, which unite under a faded green truss bridge a block away.

I'm chatting with the chef of the Grubstake Saloon on a sidewalk bench when a high-pitched zipping sound breaks the afternoon stillness. I've been expecting this. It's the unmistakable din of knobby tires rolling on blacktop.

Bug-eyed and mud-caked, the speeding bikers zigzag down Main Street, in packs of threes, fours and fives, crowing over their conquest of a high-speed dirt-trail plunge from the 7,100-foot summit of Sierra Buttes.

It's a noisy daily ritual, but few locals complain. After all, mountain biking brought Downieville back to life after the gold and timber trades died decades ago. Each year, thousands of thrill seekers take California 49 to this tiny community at the foot of the Sierra Buttes to explore hundreds of miles of converted gold mining trails.

Downieville is a true mountain biking town. All three hotels offer bike lockers, and the town's economic plan includes a chapter on mountain biking. Each July, the Downieville Classic Mountain Bike Festival multiplies the town's population of 300 to 3,000. The town has only one grocery store but two full-service bike shops, Downieville Outfitters and Yuba Expeditions. They're the economic engines of this community.

Several times each day during the dry months, shuttle vans loaded with riders and mountain bikes roar out of each shop to the trail head at Packer Saddle, near the summit of Sierra Buttes. An hour or two later, those same riders come screaming down the mountain, crowding the quiet streets with knobby tires and sweaty Lycra.

In between the daily adrenaline parades, Downieville evokes the peaceful atmosphere of a tree-shaded, Old California burg. Everyone seems to move with the grace of the swaying pines. A block behind Main Street, a man in rubber gaiters casts for trout at the union of the Yuba and Downie rivers. A few yards away, a gang of lanky teens swings over the water from a rope fastened to the bottom of a single-lane bridge.

Looking for something to eat, I wander into Gallows Cafe & Pizzeria -- named for the 1880-era gallows near the local sheriff's station -- and vacillate when the cashier asks for my order.

"Take your time," the pizza worker says. "You're on Downieville time now."

RIDE FAST OR ELSE

A teenager in full-body pads trembles with adrenaline as he sits on his bike at the Packer Saddle trail head.