Hang a sharp left and leave Seminary Avenue, and civilization, behind. Pedal up the rocky, dusty hill, then lean forward as the woodland trail descends to a tricky stream crossing.
"It's like you're 11 years old again -- 'Yee-ha!' " says Joe Surkiewicz. "It's the knobby tires. It's the motorcycle-style handlebar."
It's mountain biking, a sport in which Generation X thrill-seekers soar and twirl on two wheels. Where tumbling headfirst over the handlebars is an "endo" or, potentially, a "face-plant." Or even a "yard sale" -- a crash that leaves a rider's belongings strewn about.
But hold the Mountain Dew.
Like mountain bikers across the country, Baltimore riders are battling to stave off local restrictions on the sport.
Last winter, Baltimore officials proposed a ban on mountain biking on land surrounding the city's reservoirs -- including popular trails around Loch Raven Reservoir -- citing concerns about the effects of erosion on water quality.
Cyclists are also worried about a state proposal to set aside thousands of acres of parkland as "wildlands."
And while a compromise with the city -- which would allow mountain biking with some restrictions on watershed land -- appears likely, bikers remain braced to fight off further assaults in an urban area with few outlets to practice their sport.
"It horrified everybody, the fact that they say mountain bikers endanger the drinking water," said Surkiewicz, an officer in the Maryland Association of Mountain Bike Operators, or MAMBO. "It's like, 'Wow, we're the biggest environmentalists around.' "
On a recent afternoon, a small group of MAMBO members gathered for a ride at Loch Raven.
From their customary parking spot, near Seminary Avenue and Dulaney Valley Road, the riders pedaled a quarter-mile to the trail head. After climbing that hill, they pedaled a short, level stretch and then headed down to the first stream crossing.
Despite the sport's image, its leading protectors in Baltimore aren't twentysomething daredevils. While they may ride hard and steadily, Surkiewicz, a 45-year-old free-lance writer, does not apologize for walking his bike on the crossing's slippery concrete.
"One of the things we wanted to dispel is that this is just a bunch of kids running amok," said Dave Tambeaux, a 37-year-old mortgage banker who frequently rides the trails around Loch Raven Reservoir. "We're more like the average person down the street than kids with too much energy."
The biggest draw to mountain biking seems to be the communion with nature. It is like a hike -- but with a dose of adrenalin.
And to do it without polluting the air, as a motorcycle would, well, that's all the better, said Scott Beeson, a 38-year-old marketing director for the Bicycle Connection, a chain of bicycle shops.
'A religious thing'
"I guess there's a sense of alternative lifestyle hooked in with it all," Beeson said. "To me, at least, being outside is like a religious thing."
At Loch Raven, bikers wind through a lush forest and occasionally glimpse a deer or a hawk. They ride more than 20 miles of fire road and sometimes branch off onto smaller trails called "single-tracks."
One such trail leads to one of the watershed's landmarks, Sam's grave. There, a loyal pet's final resting place is marked with a tombstone and dog toys.
Janice Spiciarich rides Loch Raven's trails once or twice a week and has the scarred legs to prove it. When she mentioned that she was looking for the Sam's Grave Trail, MAMBO member David Duvall gave her directions -- and explained a local mountain biking tradition.
"Be sure you say hi to Sam when you go by," said Duvall, a 28-year-old bike messenger who is a walking billboard for Trek bicycles.
Duvall -- wearing Lycra shirt and shorts, wraparound sunglasses, bandanna and a ponytail under his helmet -- looks the closest among the MAMBO riders to the image of mountain biking presented in commercials for highly caffeinated soda.
Nationally, as the sport has gained popularity, resentment from hikers and bikers has helped spawn movements to restrict mountain biking on public lands. In Marin County, Calif., birthplace of the sport, tales abound of bikers bowling over hikers and of hikers sabotaging bike trails with a sprinkling of roofing nails.
In Baltimore, the tension between hikers and bikers appears to be limited. The proposed ban was motivated solely by the water-quality issue, said Kurt Kocher, a spokesman for Baltimore's Department of Public Works, which oversees the watersheds.
But bikers saw themselves as scapegoats and demanded to see scientific evidence that their sport is to blame for any drop in water quality. City officials are conducting an environmental study.
Meanwhile, the task force met this summer to come up with regulations to govern biking at the city watersheds.
Resolution at hand
"That's all going to be coming to a conclusion pretty soon," Kocher said, adding that Public Works Director George G. Balog must approve the plan.