JERMAINE Alexander learned to ride a dirt bike before he could write or tie his shoes.

"Maine" was 5, and he would ride his bicycle only if he smashed tin cans in the wheels to mimic the dirt-bike growl. So his uncle took him to the park to teach him to ride the real thing.

When he was a teenager and would hear one roar by on the streets outside, he'd stampede to the window to see who was riding what. He became so adept at fixing them that he could transform scraps of junkers into bikes that, though not beautiful, still flew fast as fireworks. The Frankford teen even dubbed himself "Dirt Bike Maine," a nickname that caught on among his friends and family.

His mother wasn't crazy about his obsession. Dangerous, she knew. Illegal, too, even though the bikes and other all-terrain vehicles buzzing around city streets taunt police with their ubiquity.

Yet, Alexander's mom bought him two dirt bikes for Christmas in recent years.

"I knew he loved to ride," his mother, Sarina Howard-Witherspoon, said. "There's a lot of kids his age out there selling drugs, shooting people. He ain't one of those kids. The only thing he wanted to do was ride that bike."

On March 13, the 14-year-old sprinted from Warren G. Harding Middle School to a friend's house to borrow a dirt bike. He and a buddy returned to school to ride past their classmates at dismissal, a show of coolness.

What happened next is in dispute. Eric Carter, 15, who was riding with Alexander, said cops in a marked police cruiser spotted them at Frankford and Oxford and gave chase. Police say there was no chase.

The boys split up and sped up.

After more than a mile of zigzagging through Frankford, Alexander's ride ended on Frankford Avenue at Butler Street, when he collided with a car that turned in front of his speeding bike.

The bike shattered.

The boy died.

A month later, his family's grief has grown into fury.

"You got kids out here, killing and selling drugs. I got a kid that rides bikes and plays football, and that's your concern?" Howard-Witherspoon said of the police.

The case highlights inherent flaws in how the city handles one of its peskiest problems. Although it is illegal in Philadelphia to drive a four-wheeler or dirt bike on streets or in parks, the department has a no-pursuit policy for the vehicles, saying that the dangers of a chase outweigh the offense.

"Having a blanket policy that police can never chase means riders will always flee," especially when they know that if they stop, their bikes or four-wheelers will be confiscated, said Peter Moskos, an associate professor at New York's John Jay College of Criminal Justice and a former Baltimore cop. "No-enforcement is not going to solve this problem."

Driving cops crazy

Their motors are deafening. Their street maneuvers are dangerous. And they destroy parks, playgrounds and private land.

"Every community meeting I go to, the No. 1 complaint I get is the noise of these things," said Capt. Frank Vanore, commander of the 25th District, which spans parts of North Philly, Juniata and Hunting Park.

Moskos added: "Cops hate these guys with a passion, because besides quality-of-life issues, they're an affront to police authority." Besides so easily eluding capture, four-wheelers and dirt bikes irk police because they're popular among drug dealers, who hire lookouts to ride them around and alert them to oncoming cops and competitors.

Yet, the riders are just as passionate and plentiful as their critics. Cruise through Kensington or North Philly any evening or weekend when the weather's warm and you're liable to be book-ended by four-wheelers or passed by wheelieing dirt-bikers.

"It's fun," Carter said, explaining why he rides when he knows it's illegal.

Riding dirt bikes and four-wheelers is a rite of passage for many urban youth, said Jeff Deeney, a social worker who works with young criminal offenders.

"It's part of a whole set of reckless behaviors that go along with being a young, corner-hustler kid, just having your ATV or bike and blasting wheelies up and down the block. It's a 'Go f--- yourself!' to the cops," Deeney said.

They're an affordable, accessible thrill, experts agree. They cost anywhere from a couple of hundred to a couple of thousand dollars at garages and dealers throughout the city. Because they're cheap and illegal to ride in Philly, many owners don't register or insure them, making them prime targets for theft.

As for stopping them, "there's not a whole lot [police] can do," Vanore added. Pursuits endanger passers-by and other motorists, and four-wheelers and dirt-bikers can go places police cruisers can't, like the wrong way on streets, on sidewalks or up narrow alleys, he said. That means that cops nab them only when they can successfully sneak up on them in unmarked cars or in tight areas, or when riders stop for fuel or return home.

But confiscating them gives cops little comfort.

"They get them right back," Vanore said, referring to a policy that allows owners to retrieve them if they show proof of registration and insurance.

Even if they don't have that paperwork, they can buy them back at auction, cheaper than buying new, Vanore added. The Philadelphia Parking Authority sold more than 300 ATVs and dirt bikes seized by police, and returned more than 60 others to their owners, between 2007 and 2011, spokesman Marty O'Rourke said.

Selective policy

Some bikers insist that police often ignore their own rules.

"Some of the cops let you keep going; they don't chase you. But then you got the cops, gung-ho, or they had a bad day, who want to chase you," said Jaryn Warren, 27, one of Alexander's friends.

"If they chasing you, they gonna bump you. They trying to hit you so they can knock you off the bike," Warren added. "You got to keep going, because you stop, they take your bike, and they gonna say you agg-assaulted them. They gonna say you driving recklessly. The story gets switched all over."

Deeney added: "I think there are a lot of official police policies that aren't necessarily the actual policies enacted by officers working a particular beat."

Police deny that such activity occurs.

"Not happening," police spokesman Lt. Raymond Evers said.

Alexander's family has hired a lawyer. They claim that cops repeatedly chased Alexander in recent years, even "bumping" his back tire as recently as the day before he died.

Citing witness reports, they believe that his bike collided with an unmarked police van involved in the pursuit. They plan to file an Internal Affairs complaint, and their attorney, Scott Portner, is calling for an independent investigation by the state Attorney General's Office or similar agency.

"My child didn't deserve this," Howard-Witherspoon said. "These people [are] just covering up all types of things. Somebody's going to pay for my son's death. I want justice for this 14-year-old." Police deny any chases or contact.

"Tell them to show us the video," Evers said of Howard-Witherspoon's claims.

The first step in getting dirt bikes and four-wheelers off city streets, Moskos said, is changing the institutional attitude of inevitability.

"This is not a natural rite of spring. The culture can be changed," he said. "I'm generally not for pursuit, for all the standard reasons. But police should enlist the help of the community, the church leaders, to crack down on this" and garner support for changing policy so that police can pursue scofflaws.

Stiffer fines for violators, and making it more difficult for owners to retrieve seized vehicles, would help, Vanore added.

"Give poor kids in poor neighborhoods more outlets for constructive outdoor activity," Deeney suggested.

Evers added that parents should be held accountable for their kids' offenses.

"It comes down to parental responsibility," Evers said. "We [police] can't control everything. The parents need to step up and say, 'No, you can't ride that.' "