For the road riders, speed is a drug that's hard to quit.
You can't kick the buzz. Yes, they know the risks, but they're happy to take them at 200 miles per hour.
Hundreds of riders bomb down Ireland's country roads on summer evenings - the air is thick with the growl of revving engines.
And on the sidelines, the wives, the partners, the children stand and watch and wait - holding their breaths, counting down the laps.
They cope with the wait and the worry for a son, daughter, husband or father to reappear again and make the chequered flag. But they cannot stop the racers.
Speed kills but it also thrills.
Warren Reeve grew up with road racing; it's in his DNA.
"It's a bit like going in for a fight," he said.
"You get nervous, you get the butterflies. You're just sat on the clutch and it's all focus and then all that nerve turns into energy."
Lewis Hamilton stuff?
He is wary too, he understands the risks but he has a passion for racing.
"You have to be at one with the bike, you have to feel the road through the tyres and the handlebars," he said.
"I'd never fall out with the bike because she's bigger than me. You see the young ones getting off their smaller bikes and they're kicking the bike and I'm thinking no, don't do that, she'll get you next time."
His wife, Jeanette, has her own views but she knows she can't stop him.
"He's born with race fuel in the blood, I'd love him to stop," she said. "Why would you race on crazy roads?
"He promised me glamour, I was thinking Lewis Hamilton stuff, high heels and make up. But no, it's wellies and raincoats."
And she's got used to the thrills as well as the spills.
"It's normal now, it's a good life, a scary one," she said. "There's a dark side, I've seen it first hand, but it's what we do."
Robert McCrum is in love with the sport. He has lost a leg, but that hasn't grounded him.
"The doctor said he would make me a limb for the motorcycle," he said.
"I have a different limb for racing," he added, strapping it on in a matter-of-fact way.
"You always want to win... But if it doesn't work out, it doesn't work out, no point in getting annoyed."
The family come for the racing, he always brings the children, saying it's like "a wee holiday".
Melissa Kennedy thinks she's immortal but, deep down, she knows she's not.
Her passion for road racing comes courtesy of her genes. "My dad is such a strong figure to me, he's my hero," she said.
"Dad bought me a bike for my birthday, he made me get on it and that was it. Once the visor goes down, I'll get a tap on the back from my dad and he'll give me the thumbs up and that's it, I'm off.
"Mum hates me doing it but she comes to every race because if she didn't she would be beside herself if anything was to happen me and she wasn't there.
"But she can't bring herself to watch me."
The enthusiast is passionate about road racing.
"Racing is my love," she said. "If I have to give it up I will, but at this present moment in time, I'm sweet."
Things don't always go right. People are killed and the racers mourn together.
They are, many of them say, "one big family". They are bonded by their passion for the sport.
Their stories are told in a series made by independent production company, DoubleBand Films.
Photographer Stephen Davison has also captured the essence and individuality of Ireland's road riders in a series of haunting portraits to accompany the series which also form a touring exhibition.
The first episode of Road Riders in on BBC One Northern Ireland at 22:40 BST on 19 April.