The Great Divide Mountain Bike Route is one of America’s best big adventures, traversing thousands of miles of remote dirt roads and high-altitude trails through the Rocky Mountains.

And 68-year-old Dave Tullier is tackling it alone.

A Baton Rouge bicycle mechanic, Tullier rode 988 miles of the route’s northern half last summer and is training to finish the southern half this summer.

“I like to see the country,” Tullier says. “Being a flatlander from down here, I love the mountains. I love climbing just to see the geography.”

The terrain ranges from snowy peaks and clear rivers to arid basins. The route crosses few towns, leaving Tullier far from reliable cellphone signals, hospitals or bike shops.

On the trail, the short, muscular Tullier rides a rugged fat-tired mountain bike loaded with all the camping and cooking gear he needs, plus a cowbell tied to the handlebar to discourage bear attacks.

Some friends admire him. Others think he is crazy for riding solo in his 60s.

Yet Tullier sees his age as an advantage.

“I am smarter, more wise,” he says. “I have more patience with myself climbing and different things like that. I don’t know if I would have attempted it when I was younger.”

Like most children of his generation, Tullier grew up riding bikes everywhere around his hometown of Alexandria. When he visited his uncle’s Schwinn shop in Lake Charles as a teen, he learned the basics of bike repair.

After serving in the Marines in Vietnam, Tullier returned home, bought a bicycle and completed his first century — a 100-mile ride — from Alexandria to Monroe, where he attended college.

He told people daily bike rides were his “happy hour.”

Following college, Tullier taught school for five years and then worked in bike shops.

For a while he owned and managed two stores. Over the last two decades, he has run a mobile bike repair business, Dave’s Bike Repair.

After moving to Baton Rouge in 1997, he began tackling more long-distance bicycle tours, taking off for weeks at a time to pedal across the country. Over three summers in the early 2000s, he rode the Lewis and Clark trail, which follows the explorers’ path from Illinois to the Pacific Northwest. On another, trip he traced the Mississippi River from north to south.

Each time he shuts down his repair business for a few weeks.

“A lot of people wait on me, and a lot of people like that I tour,” Tullier says. “That’s the only way I can do it.”

Since the Great Divide Mountain Bike Route was mapped in the 1990s, it has called to Tullier.

Over the past two years, he built a custom bike for the trip, a steel framed “fat bike” with balloon tires made to handle dirt, mud, sand or snow. He pulled a trailer and, instead of cycling shoes, he started using hiking boots.

He trained on the gravel paths atop the Mississippi River levee and prepared to climb for miles and miles up the Rocky Mountain passes.

Last July, he drove to Helena, Montana, to start his ride south. The Great Divide follows dirt roads and narrow bike trails — and a few paved roads — and crisscrosses the Continental Divide dozens of times.

Tullier saw the massive mountains of the Teton range in Wyoming and climbed mountain passes at 9,600 feet above sea level.

He saw two bears — one grizzly and one black bear — but was never in real danger. Along the way, he met hikers and other cyclists taking on the route, making friends from all over the world.

Knowing he was far from hospitals — and help — he took some mountain descents cautiously. After hitting 29 mph on one downhill, he decided to slow down.

“I thought, ‘Don’t do that again,’” he says. “The road can be great, then all of a sudden it goes to hell. You’re out there in the middle of nowhere.”

This summer, his trail will traverse the southern Rocky Mountains, from Steamboat Springs, Colorado, to the border with Mexico. The higher altitudes and tougher roads will test Tullier over the four or five weeks he plans to ride. But his experience gained over a lifetime cycling gives him an edge.

“It’s going to be tougher,” he says, “but I know more.”