'My daughters are very good guinea pigs,' Van der Merwe says with a smile. If you don't get proper market feedback in the long-term especially in this competitive industry, you'll do yourself in. They tell me what they like.'

It all started with Lilka's birth in 2006. Her arrival inspired Van der Merwe to take a fresh look at the traditional plastic scooter. Van der Merwe didn't want to just repackage the original, but to build something that would help his daughter grow.

'We asked: 'What does the child need?' And we tried to design around those needs,' he says.

Until then, his design team at Chrome Cherry had worked on an eclectic mix of products: satellites for the South African government, petrol station exteriors and shop fittings. But never toys.

'When we launched the YBike Original in South Africa, retailers weren't interested when we told them we were going to launch the old plastic scooter bikes,' Van der Merwe says.

'I showed them computer images first. Then we took the prototypes to them and they placed their first order on the prototypes.'

Orders soon started coming in from Asia, Europe and the United States. The company moved its international production to China, which now makes every YBike sold outside South Africa.

'Exporting from China is so much easier. The systems are in place, the factories are in place and the people know what they are doing. Coming from a Western side sometimes people have their own impression about Chinese manufacturing, but I always tell people when I go back home that that's not true,' Van der Merwe says.

What makes the Original different is its thick back wheel, low-set seat and angled handle bars.

'While it looks like a really cool ride-on scooter, it's more of a balance scooter,' he explains. 'Because there's one back wheel it allows the child to do counter-leaning, almost like driving a motorbike when you go into a corner.

'Instead of just turning the handle, you counter into the other side. You counter-balance. And that is so important for their development at that age. It gives them confidence.'

As the designer's family grew, so did the YBike's family of products. Soon after the release of the Original model in 2007, came the Extreme, a taller bike with an aluminium frame for children over three.

Following the birth of Van der Merwe's second child, Yani, the team began to look at baby walkers. The result is the Pewi, designed for babies from nine months. It was released in late 2010 and has already won a clutch of awards.

'At that stage of child development they do a lot of body and space awareness; understanding where my hand and foot is in relation to my body. So we did a lot of research as to how we could stimulate that sort of development at those early ages,' Van der Merwe says.

The designer reckons his daughter Yani is his proof of the product's success. 'At nine months she was walking. She's just over two years now and she's already riding the Extreme as if she's a pro. I really believe it's from having the confidence and the skills,' he says.

The company calls it 'Yvolution'. The idea is that babies start on the Pewi before taking up the Original. At three, they move to the Extreme and then onto pedal bikes, completely bypassing the need for stabilisers or training wheels.

'The moment you take the balance aids away it becomes an issue for them. That's why children struggle sometimes moving from stabilisers to pedal bikes. If you really want to teach them proper balance you should give them balance exercises. You shouldn't stunt it,' Van der Merwe says.

The designers were so convinced that the YBike Original would improve children's motor skills, they commissioned a report to back their claims.

Researchers from the University of Stellenbosch in South Africa encouraged 19 preschool children to ride the bike for 15 minutes twice a week for four weeks. Tests conducted before and after were said to show dramatic improvements in their balance and co-ordination.

The report said: 'Although the kinds of play experiences the children were having outside of their creche could not be controlled, the kinds of improvements in balance and coordination found in this study are well outside of what is expected in a four-week period.'

Van der Merwe and his team used the research to create a 'Skills Programme' for every YBike user to follow, but their real marketing masterstroke has been to offer free bikes to kindergartens so that potential customers can try the bike and track their progress.

Many times, Van der Merwe says, the kindergartens keep the bikes. Parents learn about the trials and the word-of-mouth marketing spreads.