Zipping around, amid the traffic of Kenya's capital city Nairobi, are hundreds of electric bicycles from the Kenyan start-up eWaka Mobility.

Founded in 2021 by Celeste Vogel and Jimmy Tune, eWaka aims to provide a comprehensive service for delivering goods to the doorstep, known as the "last mile".

As well as selling e-bikes and training to individual riders, eWaka markets to companies wanting a whole fleet of e-bikes and the software to manage them.

This is the third in a five-part series on technology in Africa.