Fifteen feet below the dirt singletrack of the Duluth Traverse mountain bike trail, where I was jouncing downhill, rust-hued water dashed white over ledges of basalt the color of storm clouds. All around me, stunted birch trees with yellow leaves grew crookedly from the thin soil. I tapped the rear brakes every few moments and tried not to grip the handlebars too tightly. I rode high on a berm, then hit a series of bumps and both tires left the ground.

"Oh!" I exclaimed, shocked by the thrill.

I was on the first of two trips to ride the Duluth Traverse, an off-road multiuse trail system that connects a growing web of trails across the city. I had begun riding on the west side of Duluth, from one of the trail's many access points. The switchbacks began immediately. Within minutes I was breathing in a raw way that sounded more appropriate for climbing toward Mount Everest than Enger Tower. The air was cool and moist. It smelled of conifer needles and open water. The trail crossed hummocks of bedrock that emphasized the mountain in mountain biking.

"It seems like they're spitting out miles of new trail every month," said a local biker, Max Elfelt, with whom I stopped to chat. The city of Duluth and the Cyclists of Gitchee Gumee Shores, or COGGS, a nonprofit that supports biking in the Twin Ports, are jointly responsible for trail work.

"The Duluth Traverse is a spine trail that links together other trail systems," said Hansi Johnson, director of recreational lands at the Minnesota Land Trust. Ten years ago, he was with COGGS when the group pitched the idea to former Duluth mayor Don Ness.

Altogether, the trail systems currently total 89 miles, said Jim Shoberg, senior parks planner for the city of Duluth, connecting people to green spaces and wild lands. Thirty-three of the traverse's eventual 42 miles are complete. Several linked trail clusters offer harder riding and total 56 miles.

With additional trails planned, Duluth will ultimately boast 129 miles of mountain biking. While the trails are built for biking, all human-powered silent sports users are welcome. During my rides, I occasionally shared the trail with hikers, joggers, and dog walkers. Legacy Amendment grants, local tax proceeds, and private donations funded trail construction.

The Duluth Traverse begins along the St. Louis River just downstream from Jay Cooke State Park and stretches to the Lester River on the eastern edge of Duluth. The western half is mostly continuous, while the east side is patchier, using road connector routes to get from trail to trail.

"We hope to close most of those gaps this year," said Shoberg.

On my second visit to the traverse, Greater Minnesota was sweltering. Duluth was foggy and cool. Riding on the hillcrest, I watched coils of mist swirling about a freighter in the harbor. I dropped into a valley and began a long descent. With the city lost from sight, the valley could have passed for boreal wilderness until I rode under a steel train trestle, where the ground was covered in pea-sized taconite pellets that had shaken loose from trains rumbling from Iron Range mines to Lake Superior docks. How emblematic this was of Duluth: In the delightfully deep woods of the state's fifth-largest city, mining roots melded with a burgeoning identity as a regional mecca for rugged outdoor play.

I was cast from the woods when the trail met a residential street. I followed the connector route using a biking map app on my phone, then rejoined the traverse at a wooden bridge over stony Kingsbury Creek. In a grove of white cedar and pine, I dismounted and reclined on the soft duff of orange needles. I inhaled the tangy air and a salami sandwich.

The traverse continued to the base of the Spirit Mountain ski hill, where a cluster of trails laced the slopes. The route headed to the road for a few miles before reaching its final legs in the Mission Creek section. I left the beginner rating of the traverse for an intermediate side trail. The switchbacks out of the Mission Creek valley were the steepest I rode.

The trail hugged the undulating St. Louis River valley wall, wrapping through many gullies, some red-soiled and raw from the mudslides and record rains of recent years. I topped out on a ridge covered in aspen and maple, and here I again joined the Duluth Traverse, which I followed along a fun course of dips and climbs.

After a day of riding, as the light grew dim, I was walking my bike along the trail up a hill beneath Enger Tower. I heard the shifting of gears from behind and moved over. A man wearing spandex and a headlamp rolled by on a carbon-framed bicycle.

"Nice evening for a ride," he said, breathing effortlessly in a way I simultaneously resented and admired.

I gingerly straddled my bike and began pedaling. I'd seen more cyclists on this section than the others I rode. It was centrally located, with postcard views of the harbor and the lift bridge. I had hoped to ride farther east, but lights were flickering on in the lakeside buildings and my legs felt like yardsticks. I returned to my car and headed home, wondering when I could make my next trip north.