In some countries such as Nepal he said there is a “very sparse coverage” with just one fire engine in a 200 mile (321km) radius.
In Germany, he found “the fire service was well-funded and well run”.
He stayed overnight at some of the fire stations on some occasions, including in Gospic, Croatia.
“They were very welcoming,” he said. “There is a universal understanding about being a firefighter.”
He told BBC London he gets up at 7am every morning and cycles for five to six hours each day.
“I wake up every day and I’m glad to be alive. It’s been absolutely fantastic so far.”
Stephen added: “I have to say people really are wonderful.”
Apart from a stomach bug, he has had no major health problems so far. His bike is also wearing well albeit with the odd puncture.
“I try and get my bike serviced regularly so I avoid any problems,” he said.
So far his highlights include seeing a “magical” lunar eclipse on a beach in Turkey and visiting the Taj Mahal in India.
“I also rode up on a high plain in Nepal and then suddenly saw a vista of the Himalayas in front of me – it was amazing.”