Unlike a medical doctor who relies on a stethoscope as a tool of trade, Dr Bike uses spanners to fix his sick "patients".
Joseph Karrs is popularly known as Dr Bike in parts of Kliptown, Eldorado Park and neighbouring areas in the south of Johannesburg.
He is not a trained medical doctor, but a self-taught bicycle fixer.
"I can build a bicycle with my eyes closed and I can fix any type of bicycle," he boasts.
The 57-year-old father of nine started fixing bicycles as a teenager.
"My love for bicycles started very early when I was in primary school. It started as a leisure hobby and later it became my bread and butter," he says.
When you enter his house in Eldorado Park, parts of old and new bicycles are scattered across his yard.
Parts like rims, worn out tubes, tyres and old frames can be seen hanging on the fence.
Inside his yard, there are two shacks at the back, one used for his church services and another as a workshop.
However, the man suffered a setback when a neighbour stole old bicycle parts from his workshop.
"I only realised two months later, when I looked for spare parts, that there has been continuous break-ins. The culprit was later killed by his stepfather during a fight over drugs," he claims.
Karrs plies his trade in Kliptown next to a filling station.
Looking for him is simple. You just ask anyone in the area where he can be found, and they will simply direct you to his spot.
At his spot, there is a bike standing next to him carrying parts.
"Cycling is my life and I live for bicycles," he says.
Early 70s
"It all started in the 70s when I was attending at Nancefield Primary School. Our principal encouraged us to have hobbies and participate in various sporting codes.
"Accidentally, I built my own bicycle because I didn't like walking to school, and our principal was very impressed and he told me that fixing bicycles will be my career. He was right. Look, today it is bringing food in my house."
Karrs' life took a bad turn when he was arrested and sentenced to nine years in jail for robbery in 1990.
Upon his release from Johannesburg Prison, also known as Sun City, in 1999, with a criminal record hanging over his head, Karrs could not find employment and he decided to look no further than his existing talent - fixing bicycles.
"When I came out, I told myself that I am not going there again. I looked for a spot in Kliptown where I started fixing bicycles. I first worked in someone's yard to attract customers and later moved to my current spot after I have established my [client] base.
"I fix between five to 10 bikes on a profitable day. I also teach youngsters to ride bikes. Cycling is one of the healthy lifestyles. Imagine if we all cycling to go nearer to places, our health will be up to date," he said.
Karrs has shared his talent with his five children, including his daughters.
"My children can fix any bike, except for the young ones. I have given them something that will also put bread on their tables. Bicycles are going nowhere in this world, they are here to stay and their future looks bright."
Karrs is worried about the future of youngsters in Eldorado Park and blames loitering and idling in the township as a big contributing factor to drug addiction in the township.
My wishes
"I wish I had funds and a proper place where I would teach the youth about cycling and fixing bikes. Our children need things that will drive them away from idling and doing nothing with their lives.
"There are no sporting facilities here. Our children are left to wander around doing nothing and are easily hooked on drugs and crime [as a result]," he says.
"If my children can do it then anyone can. All I want is a better platform to teach the youth in order to sustain themselves in future."