Joe Scherer glides down the face of the ramp, kicks twice to pick up speed, then hits another ramp, this one going up. He takes flight, one arm outstretched and the other gripping the board to his feet as he arcs 6 feet into the air, landing smoothly on the downside of the ramp. Over the racket of other thrashers dropping in, grinding and occasionally planting at Ollie & Co. Indoor Skatepark in Ham Lake, Scherer, 33, explains the appeal. "When you hit it right, it's the best feeling in the world. Besides my wife and kids, this is second on the list in life," he said. "I come here with my son at least once a week." Scattered in the suburbs, three skate parks cater to riders who don't want to let the seasons interrupt their love affair with their boards. And while most of the patrons are teenage boys, there are plenty of stereotype-busting exceptions, from daycare kids to Peter Pan dads.

Erik Evenson remembers the moment when building an indoor skateboarding park came to mind. He was dropping off his sons at an outdoor skate park near his home a little more than two years ago.

"There was a kid lying on the ground with a broken leg," he said. "I said, 'When is your mom coming back?' And he said 'In about an hour.' We called his mom on the cell phone and got him to the hospital, but that incident stuck with me."

As a parent, Evenson wanted a safe place for his kids to ride, and he figured that many other parents would feel likewise. Thus, Ollie & Co. Indoor Skatepark in Ham Lake was born.

Chuck Youngquist looked at the growing number of skateboarders and decided that an indoor skateboard park might be a good business. He and a partner opened the Showcase Indoor Skate Park in Rogers almost two years ago.

"Last year at this time, we had 1,800 members; today it's more than 5,000," Youngquist said.

Mark Muller and his partners had a different motivation when they opened the 3rd Lair Skate Park in Minneapolis 10 years ago. "It was out of complete selfishness," Muller said. "It's Minnesota, it's winter and there was no place else to skate. So we made our own place." The park has moved and grown, and now has indoor and outdoor areas at an expansive complex in Golden Valley.

California is the center of the skateboarding universe, but Minnesota has its own skateboard culture and stars, and the indoor parks are great places to catch a glimpse.

Ollie's

Tim Bennett raises a megaphone, cranks the siren and bellows in his best baritone police-officer imitation. "Exit the park with your hands up! This session has ended and you must now exit the park!"

About 20 boys and two girls glumly pass through the chain-link fence that separates the lobby from the cavernous open warehouse space, skateboards under their arms. Another group, moving much more quickly, enters. A handful of veteran skaters who either work at Ollie's or have a coveted place on Ollie's demonstration team never have to leave; as the sessions end and begin, they continue rolling up walls, flying over obstacles and sliding atop stair rails.

The concrete walls are covered in taggers' marks and spray-paint murals; in one a 30-foot-high blue goddess leans down, bequeathing her subjects with a proportionally huge skateboard.

On the floor, ramps and stairs are arrayed to create "flow," or the possibility of a series of stunts as a rider passes from one side of the room to another. "I think of a really good run as riding concrete waves," said Bennett, 24, who manages the park and manages to skate quite a bit, too. "Learning a new trick is just the best feeling in the world. It makes me feel like a modern-day ninja."

The age range on the floor goes from 33-year-old Joe Scherer of Roberts, Wis., who is jumping ramps with his son Justin, 8, to a couple of tentative 6-year-olds, who seem to enjoy watching the accomplished riders as much as working on their own stunts.

Showcase

Skateboarding is a challenging sport; all three parks require helmets and parent-signed waivers for those under 18, and waivers for those over 18. The whole joy of the sport lies in defying gravity in various ways, but gravity can only be challenged for so long before it must be obeyed.

"These kids are tough," Youngquist said, watching a group of 14-year-olds fly off a set of steps and across the floor at Showcase in Rogers. "I've seen one kid land off these stairs on his tailbone, roll around on the ground in pain, and a few minutes later he's flying around the place again. One time I had a kid walk up to me with his front tooth in his hand saying, 'What should I do with this?' We put it in the fridge and his dentist stuck it back in later."

At Showcase, one steep ramp feeds skaters toward the foam pit, where they can perform flips and twists in midair before landing safely in a swimming-pool-sized bin of gray foam blocks. Ryce Thiel, 8, of Princeton, Minn., was hurling himself into the pit again and again with Sisyphean tenacity.