Mucina, Boniface and Kama are among the motorbike boys of Dirt Island in Nairobi, Kenya - young men who have discovered a new way to improve slum life - a two-wheeled taxi service.
You can see how it works around sunrise and sunset here in the slum known more formally as Korogocho. It can be a slightly surreal scene - a besuited gentleman, briefcase in hand, riding pillion on a motorbike across the litter-blown and rutted alleys of the Dirt Island.
Dirt Island dwellers who use the bikes - they include civil servants and businessmen - are not just paying for a lift for speed. It is also for security.
"Sometimes I use these bikes when I'm late from work, because the road is not safe at night," one passenger said. "So these bikes really help us a lot!"
The irony is, the Dirt Island's motorbike taxi service is being run by precisely the kind of young men who might have menaced their passengers in the past. Many of the motorbike boys were once offenders.
This is not a well-meaning reform project organised by outsiders, trying to reach the elusive Millennium Development Goal on improving the lives of slumdwellers.
Mucina was there when they had the idea - the profits of crime ploughed into a legitimate business that would lure people out of crime.
"I bought a bike, an old motorbike," he says, "and set up at the (taxi) stage. At first people weren't comfortable with riding the motorcycles but after we became many, people got used to it."
Mucina, Boniface and other leaders recruited young men like Kama.
"I never planned to be a motorcycle boy," he says. He cannot afford his own bike - gambling has seen to that - but when he heard "the cops were hunting for me and 'counting my bullets'," he decided to hang around at the stage, hired a bike and now works it hard, paying for repairs from his profits.
"Most of these guys are reformed criminals," Mucina says. "We tell them, 'Leave crime - it doesn't work,' and that they will never lack money to meet their needs and become independent."
The motorbike boys charge about 20 shillings a ride (about 16 British pence). "If business is good, I can make a profit of about 1,000 shillings," Kama says.
But he has to pay the bike owner about 400 shillings a day, and business can be much slower. "Most of my money goes on my daughter, Brigit," he says.
A lack of licences, Mucina says, meant "the police used to disturb us a lot". But they took local chiefs aside.
"We're just young people," they explained. "And instead of returning to crime, we'd like to just do this work, and gradually we'll get licenses."
There have been other little problems too, with some motorcycle boys speeding, and constant niggling repair bills.
And when some young men tried to follow the motorcycle boys' entrepreneurial lead and set up a carwash, they had their water cut off - neighbours complained about their homes flooding.
The new tarmac road circling the Korogocho slum - hence its recent nickname "the Dirt Island" - has helped enormously, cutting the constant stream of minor 100 or 200 shilling repair bills Kama has to pay to the owner of his bike.
But Boniface is less happy about new speed bumps. "They should have come and asked for our opinion... because they put in huge bumps that are meant for motor vehicles, not for motorcycles."
Scenes like those at our motorcycle boys' taxi stage are familiar across the world's developing cities.
While aid workers, officials, and journalists earnestly discuss how to help peasant farmers, the real buzz of real development - unplanned and chaotic - often goes on unheeded around them.
It may involve illegal liquor, prostitution, tax-cheating unlicensed taxis, it may be petty shoplifting or worse, but it's on the Dirty Boulevards where young men like Kama, Mucina and Boniface hang out that real change is often happening.
"If the youth are not involved in the (slum) upgrading process, it won't happen," Boniface says. "Because... the administration is not stronger than the gangs here."
"If you ask a child what they hope for in the future," Kama says, "you wouldn't find anyone who'd tell you they want to be poor. If I had my own bike, you wouldn't find me going to steal. I can't just sit still. I always need to be busy, doing something."
And then he puts it a little more directly. "This town is ours," he says.
These days the smile of the motorcycle boy who's just 'fessed up to once "harassing" minibus drivers is friendly and not menacing at all.
But it does have a message.
"If I had 100,000 shillings now," Kama says, "people would be amazed at how I'd invest it!"
Millions of people live in slums like these across the world. Improving their lives is one of the Millennium Development Goals - one that often seems just out of reach. Do we need to listen more closely to the people we're trying to help?
Life on the Edge is broadcast on BBC World News on Saturdays at 0030 BST, 0730 and 1930 and Sundays at 1330.