He is supposed to arrive at 9pm. When he shows up, it is well after midnight. But he will make up for it by spending the next seven hours and 45 minutes with me. Not because he likes me or doesn't like me. Just because that is what he does. His name is Julian Casablancas.

The lead singer of the Strokes, New York's finest purveyors of coolly detached retro-rock boogie, is blessed with the ability to talk shit. He can hold forth all night, run around in verbal circles for 15 minutes, lose his place and then start all over again. He doesn't seem to have anywhere to be. He is in the moment. He doesn't even own a cell phone, a computer or a watch. But his intentions are the noblest.

"Doing heroin is like walking around with a terrorist as your friend," he tells a buddy who has started sniffing the dust. Casablancas's cautionary monologue lasts 20 rambling, heartfelt minutes, slurred with his lips two inches away from his friend's. "It's like taking a terrorist around to parties," he continues. "You never know when it's going to blow up on you."

He is wearing a green work shirt with the words "US garbage company" over the pocket, and faded black trousers. The shirt is the property of his roommate, Strokes guitarist Albert Hammond Jr. On his wrist, there are three fraying coloured wristbands that he has not bothered to remove - one from a Kings of Leon concert a week ago, another from a Stooges show two weeks ago, and a third from a Vines show from who knows when.

I will see Casablancas nearly every day for the next week: his clothes and bracelets will not change, though he claims his underwear and socks do. He will end every night in the company of a girl he does not sleep with. And he will talk about everything from strip clubs to night terrors to his hatred of Pringles crisps. But when it comes time for a formal sit-down, he will give me the worst interview I have ever experienced. It will last seven minutes.

The Strokes are more than just a band. Whether they like it or not, they stand for something. Just as Nirvana became the face of grunge in the early 1990s, the Strokes have become the face of the so-called new garage-rock scene. And, like Nirvana, the Strokes have been embraced by the designers of runway fashion, the death knell of anything sincere.

Of course, the Strokes don't technically belong to a scene, because they were never even acquaintances with their compatriots. According to Fabrizio Moretti, the band's drummer, artist and deep thinker, the Strokes originally tried to form a scene of New York bands that would hang out, drink and go to one another's shows, but "at the time in New York, it was so competitive that bands were not open to it".

As far as garage rock goes, the Strokes don't once mention bands like the Stooges or the Troggs when discussing their second CD, Room on Fire. Instead, Hammond credits the reggae-sounding guitars in Automatic Stop to Cyndi Lauper's Girls Just Want to Have Fun; Casablancas blames the high-pitched guitar tone of The End Has No End on Guns N' Roses' Sweet Child o' Mine; and guitarist Nick Valensi pledges allegiance to goth. "There are some bass lines on our first album that were 100% ripped off from the Cure," he says. "We were worried about putting out the album, because we thought we'd get busted."

As for the famous Strokes boogie beat, Valensi says: "When we were starting out, we wanted to have songs you could do cheesy dances to - like the Carlton dance from the Fresh Prince or the Pretty in Pink dance."

The actual seed for the Strokes was planted when Pierre, brother of Strokes bassist Nikolai Fraiture, gave Casablancas a Velvet Underground CD for Christmas while he was in high school. The music was an epiphany for friends Fraiture, Casablancas, Valensi and Moretti. The dream when they formed the Strokes, according to Casablancas, "revolved around taking the Velvet Underground and thinking, 'If only they were really famous.' And the goal was to be really cool and non-mainstream, and be really popular. Why does everything that has to be big and popular suck? I got a problem with that, so I'm trying to do something about it."

At 2A, the East Village bar across the street from the basement studio where the Strokes recorded their first EP, Casablancas runs into an old friend, a large Puerto Rican with dreadlocks named Nestor.

"You probably don't remember how we met," says Nestor.

Casablancas says no.

"We were at Spa," Nestor recalls, "and all of a sudden Julian comes up to me and says, 'If you were a girl I'd kiss you.' I backed off. And then he told me his band the Strokes were playing at Mercury Lounge, and if I came he'd be my best friend for ever. No one knew who they were then. So I went, and it was really hot. The air conditioning was broken, so I left after three songs. Then I saw him later at the Cherry Tavern and told him I'd seen the show, and he bought me a drink."

An elderly Asian woman walks past selling bootleg CDs: Radiohead, Beck, Nirvana.

"How much?" Casablancas asks.

Five dollars.

"I'll give you a buck."

She doesn't even entertain the offer. Casablancas owns only three CDs: the two discs that haven't disappeared from his Bob Marley box-set (Confrontation and Uprising) and The Essential Johnny Cash. "I would've bought that Radiohead CD for three bucks," Casablancas says. "But then you might write about it, and I'd run into them backstage and they'd say something about it."

Casablancas is afflicted by something called the press. Every so often, he imagines his words blown up in big type in magazines and tries to take them back. After putting down Neil Young's voice, he backpedals: "Not that I hate Neil Young or anything." I ask him if he is always like this. "You know how bands have to decide what to wear onstage?" he says. "We just decided that we would wear what we wanted to wear onstage all the time, so we wouldn't have to think about it. So that's what I do when I speak now. No matter who I'm talking to, I always talk like I'm doing an interview."

Over time and beer, however, his disclaimers stop, his conversation loosens and his jokes get sharper. Casablancas is blessed with a quick wit, and if you listen close enough, you hear him delivering off-the-cuff comments that, when spoken in his slow, slurred voice, seem twice as funny. Out of earshot of two girls who have attached themselves to his side tonight, he explains that he didn't go to a strip club until recently, and he doesn't like them. His first experience with a heavy-grinding lap dance so scarred him that as soon as he got home, he had to beat off twice.

As he tells this story, the jukebox fills the room with the strains of Sam Cooke's soul-stirring A Change Is Gonna Come, and the girls gather round. All time stops for Casablancas. "When I hear A Change Is Gonna Come, it frustrates me," he says.

Why? "No matter how hard I try, I can never be that good," he answers.

The following afternoon, I meet Hammond at Tower Records in the East Village. He is sporting several days of stubble and a pinstriped secondhand sport coat over an inside-out T-shirt. He too will be in the same uniform every night I see him. His CD collection was stolen when his apartment was burgled last year, and he is replacing the inventory - Ziggy Stardust by David Bowie, 69 Love Songs by the Magnetic Fields, and three CDs by Guided by Voices, a band that, according to Fraiture, the Strokes aspire to be like: semi-popular, making enough money to survive and staying in the game long enough to release more than a dozen albums.

Hammond is excited to go home and listen to his new CDs. "It's like buying a bunch of pornos and waiting to jerk off," he says.

On display in the next record store, Other Music, is a CD by the young Australian garage-rock band Jet. "They make me not want to play music," Hammond says. He finds their look contrived, their music empty, their songs too samey and their CD overhyped. These happen to be the exact criticism that people have levelled against the Strokes in the past.

"In the end, I know why people make fun of us," Hammond says. "I think in interviews we come across as weird, pompous people. Then when they meet us, they realise we're nice. I want to be nice for people."

Actually, what people don't realise about the Strokes is how serious and hardworking they are, particularly Casablancas and Hammond. (In the early days, Hammond booked shows and harassed record executives, claiming to be the band's manager and using the pseudonym Paul Spencer.) Hammond's passive, grinning, soft-spoken interior belies a sense of gamesmanship and ambition.

The Strokes' so-called fasion sense can largely be attributed to him. Before he was in a band, he dressed like he was in one and enjoyed the kick of getting into concerts for free by pretending that he was in the group playing that night. He is a wolf in a thrift-shop sheepskin. And right now, he's hungry.

"I only eat two things for lunch," he says. "Breakfast or sushi."

He settles on sushi at the Blue Ribbon. As he sits down to the meal, his phone rings. It's his mother. He doesn't answer it.

"I'm a bad son," he says. "I don't call her enough. She'll just keep me on the phone and tell me that she loves me. And I'll be like, 'Yeah, yeah, yeah. Mom, I gotta go.' The last thing you want to do when you're home after a tour and your girlfriend's over is call your mom."

Baptised Episcopalian, Hammond informally converted to Judaism, he says, a year and a half ago, so that Valensi wouldn't be the only Jew in the band. "The first time I told a guy I was Jewish was in LA," Hammond recalls. "He pulled me into the corner, and I discovered this whole secret world. He even got me laid that night."

After eating, we walk to the luxury hotel 60 Thompson, where the Strokes are doing interviews with the international press. At the moment, a German reporter is asking Moretti and Fraiture questions such as "What's the difference between your first album and this one?" Mid-question, Moretti wanders away, leaving Fraiture with the reporter. "That douche-bag," Moretti says.

Outside, Moretti sits on a stoop and pensively responds to questions. We have until 11.30pm to hang out, at which point he wants to watch his girlfriend, Drew Barrymore, on the Tonight Show With Jay Leno. He drums his fingers against his leg and explains that it's an obsessive-compulsive habit - beating out the cadences of his thoughts and speech. "We have cadence in everything we do," he says. He then points to the feet of people passing. "Look, they're creating beats walking down the street. One, two. One, two. And their heartbeat is in a certain rhythm. Their fucking step is in a certain rhythm."

He admits that not everyone likes him tapping his fingers all the time. In fact, Casablancas says the first thing he thought when he met the then-hyperactive Moretti was that the kid was "a little annoying". But now, Moretti has become the group's soft-spoken intellectual.

Moretti heads to the Strokes' office in the East Village to watch Leno. Fraiture, shy, happy-go-lucky and wearing a Ricky Skaggs T-shirt, arrives in the office and collapses on the couch, not far from the two office video games - Galaga and Golden Tee. Casablancas met his bandmates over the years at various private schools - elementary, boarding and high school. When the band got serious, Fraiture decided to learn the bass his grandfather had bought him for Christmas, playing along to songs by Blur and the Jackson 5.

Unlike his classmates, Fraiture grew up crammed into a two-room apartment with his parents, his brother, his brother's adopted girlfriend and his adopted sister. He still lives in the apartment, but only with his brother now. His father was security manager at Macy's; one day, he caught his very own Nikolai stealing a Luke Skywalker doll from the department store.

Moretti flips on Leno and cranks up the sound. One of the hardest things about dating Barrymore, he says, is seeing her kiss someone onscreen. The couple met backstage at a concert more than a year ago and recently bought an apartment together in the East Village. When she comes on TV, Moretti stares at her rapt, clearly smitten. "Her mom gave her that bracelet," he says. "I gave her the necklace."

A car pulls up. The driver is here to take Moretti to the airport to pick up Barrymore, but Moretti wants to finish watching her on TV. Barrymore shows Leno some photos she has taken, two of which are of Moretti. She mentions his name, but not his band. Moretti is unsure about the whole thing, worrying that discussing him seems cheesy or boring. "She's just like that in person," he says. "So positive and energetic. That's the first thing I noticed about her."

After Moretti takes off for the airport, I meet Hammond and Casablancas at 2A. It's a rough night for Casablancas, who's complaining about how he dislikes Pringles again. Hammond (who is dating Catherine Pierce, one half of the countrified-pop sister duo the Pierces) is hanging out with the boys tonight. I last see him at the bottom of the stairs, asking where his shoes are. He is wearing them.

At 5:30am, an hour after I've left the bar, Hammond calls to ask where everyone is. He's still considering going out. The next afternoon, he calls again.

Hammond: Did you call me this morning?

Me: You called me. Don't you remember?

Hammond: OK, sure. How are you feeling?

Me: OK. And you?

Hammond: It's been a while since I went out like that. I needed that.

Me: Yeah, good times.

Hammond: Yeah. I partied so much that my ears hurt.

The next night, I meet Casablancas at an East Side dive, the 19th Hole, for a sit-down interview. You already know what he is wearing. He's tired from having spent the day battling RCA over the artwork for Room on Fire and doing interviews with the international press. He announces with evident pride that he has finally invented a stock answer to "the Nigel Godrich question". Originally, the band hired Radiohead producer Godrich to work on the CD. But their working habits didn't jibe: Godrich constantly wanted to press forward, but the Strokes like to labour over every sound. So the band returned to Gordon Raphael, who produced the Strokes' debut, Is This It, and recorded the new CD in just over two months.

I ask Casablancas what his great sound-bite about Godrich is, and he says he will tell me when we start the interview. This seems like as good a time as any. And so begins the worst interview ever. The thing about Casblancas is that he speaks and sways like he's out of it, but if you stick around him long enough, you begin to realise that he is ultra-aware of everything going on. I tell him this.

"That's your opinion," he says, almost defensively. "I see myself out of my own eyes, which means I have no idea what's going on the other way around. I just think I try to be a good person, and I fail."

With that, Casablancas reaches over to the tape recorder and turns it off. I look at him. He looks at me. Then I turn it back on and try something easier.

Me: OK, so what's your stock answer to the Nigel Godrich question?

Casablancas: Fuck you. I'm not answering that question.

Me: What the hell?

Casablancas: Next question.

Me: Honestly, this has to be the worst...

Casablancas: The worst interview ever?

Once again, he reaches across the table and places his dirty fingernail over the stop button. Then he just stays in his seat, swaying and staring. I suggest stopping the interview and just having a normal conversation, but with the tape on. He declines: "I just don't have anything deep to say," he says.

I explain that nothing deep is expected.

"I've got nothing to hide. But what I meant a few minutes ago, if I can even recall what I was saying, is just that there's so much shit to do, and so little time. And everything I have to say is not going to be in this one interview."

The issue, he explains, is that he believes in a higher power, some call it God. Right now, that higher power is telling him that it is not the right time for him to say anything. And it won't be time until the Strokes prove themselves to the world, until they do something that he terms "undeniable".

"I'd like to just get to a point where maybe we can say something that will be matterful. That's definitely not a word, by the way. And I look forward to the future, blah, blah, blah, blah."

A few minutes later, Casablancas picks up his beer, downs three quarters of the bottle in one gulp, slams it to the table, stands up and walks to the video game, Golden Tee. He addresses the bar. "Anyone want to play Golden Tee?" he slurs.

No one responds. Four minutes later, he returns to the table. "Never play Golden Tee when you're drunk," he advises.

Then he sits in my lap, kisses me seven times on the neck, and makes three lunges for my lips, connecting once. Before I can wipe dry, he is out the door, rolling himself home in a discarded wheelchair he finds abandoned outside.

The next night, I meet Casablancas at the Gramercy Diner. He has promised to behave. His eyes are glazed over from lack of sleep. "I very often have night terrors," Casablancas says. "I've died in my sleep 23 different ways." He aplogises for his behaviour yesterday. He was drunk.

Me: So does anyone ever worry about your drinking or try to get you to stop?

Casablancas: I think they know that if it gets too out of hand, I usually stop it myself.

Me: And how do you know when it's out of hand?

Casablancas: When we were doing the record I stopped for about five months. I realised it was getting to the point where it was about to have serious effects on my music. I would be too hungover to play. Drinking destroys your mental capability unless you're drinking. Whenever I was hungover, everything seemed so negative. I would be like, 'Fuck this, I need an drink.' Then you have a drink and everything is fine.

Me: What did other people think?

Casablancas: Your girfriend can leave you and your mother will yell at you, but when you start feeling like it's hurting the music, then it's a bad mistake.

Me: When was the first time you got fucked up?

Casablancas: Probably when I was 10 and there was a dinner party. There were drinks on the table. I just downed them all and was like, 'This is great.' My body immediately enjoyed it. It was like, 'Life is actually fucking amazing in every single way.'

After a cigarette break, we talk for nearly three hours. We discuss his school days, in which time he received one trophy, for his role in Bertolt Brecht's The Caucasian Chalk Circle, before dropping out of junior year; and Nirvana and Pearl Jam, who inspired him to make music. "I can't even explain it," he says of the first time he heard Yellow Ledbetter by Pearl Jam. "It was like the first time I drank." He says that if he weren't a musician, he'd be a "bartender trying to be a writer".

Casablancas is a different person from the night before, willing to talk about anything. The only taboo subject is his father, John, founder of Elite models. He divorced Julian's mother when Julian was nine, and, though Julian still sees his father, he tends to blame many of his bad habits, particularly in regard to women, on his dad. Julian remembers a joke his father once told him about a group of bulls. One bull said he could have sex 10 times a day, another said he could do it 20 times, and a third bragged that he could do it 50 times. Then a fourth said: "Yeah, but not with the same cow."

"It's not funny, really," he says, "but it has a message. I told him the other day, 'I love you with your flaws and your qualities.'"

My cell phone rings. It is Hammond. He's calling for Casablancas. This is how one gets in touch with a singer who doesn't have a cell phone. The two are planning to watch the movie Fletch tonight. Once upon a time, most of the Strokes lived together. But, one by one, they have moved apart or disappeared into girlfriend land. Casablancas is the only single member left.

Outside it is pouring. Casablancas walks into the downpour without an umbrella. Within two steps, he is soaked. I survey the detritus of the night on the table. There is a half-eaten sandwich, several empty beer glasses, an empty cigarette pack and a crumpled piece of paper. I unroll it: it is a receipt for $2.99. The date is today. Only one item has been bought: a can of Pringles.

© Rolling Stone. The Strokes play Braehead Arena, Glasgow, December 1; International Arena, Cardiff, December 3; Alexandra Palace, London, December 5 and 6.