"Pedal hard" was the sound advice from London Mayor Boris Johnson as three environmental campaigners embarked on a round-the world cycling trip.
The intrepid trio hope through their adventure to highlight the potential of solar power in the fight against climate change. Mr Johnson joined the participants as the group posed for photographs outside City Hall surrounded by well wishers.
Susie Wheeldon, Jamie Vining and Iain Henderson will use hi-tech equipment powered by the sun on their journey across the globe. They began their ride from London's south bank to Dover, the first leg of their nine-month trip on European Solar Day.
In addition to muscle power, they will have a set of custom-built thin-film photovoltaic (PV) solar panels on their panniers which will enable the latest technology to work on their mobile phones.
The gruelling 12,000 mile trip will take them through 15 countries to raise money for SolarAid, a UK charity which trains poor communities in rural Africa to build and sell small solar devices.
Miss Wheeldon, 30, from Peckham, south east London; Mr Vining, 31, who lives in France; and Mr Henderson, 35, from London, plan to visit solar energy projects and hope to demonstrate the potential for solar energy to provide a reliable and affordable solution for global energy needs.
Together with the campaign 'We Support Solar', the adventurers are calling for the Copenhagen Climate Change Conference to recognise solar photovoltaics' ability, and are also asking the UN to consider the potential for condensing solar power stations to harness the sun's rays, as promoted by the Desertec Foundation.
Expedition sponsor Nokia has supplied the cyclists with Nokia N79 Active phones, which come with a heart rate monitor and pre-loaded sports tracker so they can measure their distance, speed and pace when cycling and upload their location via GPS.
The device also features maps to help them navigate through countries including France, Tunisia, Libya, Egypt, Turkey, Iran, China and the US. The team will cross seas by ship to minimise the environmental impact of the journey.
Lincolnshire-born Miss Wheeldon said: "Solar power is an incredible natural resource that is already available. The technology to harness it has been tried and tested and proven to work. We would rather see this type of renewable energy used than resources which are fast running out."