Every day, Michael Arimi, a resident of Kayole in the east of Nairobi, Kenya, wakes up and heads to the Jomo Kenyatta International Airport where he works at a cargo handling firm.

His job involves sorting out various cargo according to size and destination before they are taken to the plane.

After completing his day's work, Arimi usually returns home and from about 6 pm, he starts his second job - running a motorbike taxi business.

"I do the work to about 10 pm and retire to prepare for the following day," he said, adding that on a good evening he can earn up to 1,000 shillings ($10).

His life is typical of that of many Kenyans in low income formal employment. The motorbikes, imported mainly from China, have offered many people a means to earn extra income, as the use of taxis has boomed in the east African nation.

The motorbike taxis are more commonly known as boda boda. While some of the workers do the job themselves, others have employed people to do it.

Among those doing motorbike taxi jobs as "side hustles" are teachers, police officers, civil servants, watchmen and drivers.

"I am an electricity meter reader by day and motorbike taxi operator by night. You cannot survive on the salary alone," said Titus Otiato, a resident of Ruai on the outskirts of Nairobi.

Otiato noted that he earns a salary of about $300, which is not enough to sustain him and his family of three comfortably.

Like many other workers in formal employment, he took out a loan of $700 from the company's savings society and bought a motorbike.

Ease of access to loans by workers in formal employment is one of the reasons many are in the trade.

Another reason is the drop in prices of the machines following the entry of Chinese brands like Boxer, Jingchen and Haojin in the Kenyan market, some of which are assembled locally.

The brand new bikes go for between $600 and $800, which is lower than those from other countries like India and Japan, whose prices average $1,000.

In Kenyan villages, teachers and civil servants are among the main owners of motorbikes, which they rent out to youths, earning at least $4 from each a day.

Fred Ajwang, a government employee in Busia, western Kenya, owns eight of them, but doesn't like to be described as a motorbike tycoon.

"I have agreed with the riders that they bring me $3.50 each day and pocket the rest they make which caters for their wages, fuel and minor repairs like punctures. This way, one works hard to make more money," he said on the phone.

Ajwang started with one bike that he bought using a loan and has been expanding his trade since.

"I get an average of $240 a day but my target is to hit $500. It is good business but I will not quit my agricultural job since that is my profession," he said, adding that his bikes are Chinese brands.

Most Kenyans are taking up the boda boda trade because it has fewer entry restrictions, according to Ernest Manuyo, a business management lecturer at Pioneer Institute in Nairobi.

"All you need to get into the business are the machines, which are now affordable, and insurance for the owner and a rider's license for those doing the job themselves. One then starts earning. It is not like starting a shop where one needs multiple licences," he said.

Chinese motorcycles account for about 50 percent of Kenya's motorbike market, with the machines injecting over $1.3 million daily into the economy, according to the Motorcycle Assemblers Association of Kenya, which notes that the boda bodas have become an important source of income for thousands of people.