Phone firm Nokia has released a charging kit that uses a dynamo powered by a bicycle's wheels.
Any cyclist wanting to re-charge their handset using the kit will need to maintain a speed of about 4mph (6km/h), said Nokia.
The charging kit is intended for nations where bicycles are ubiquitous but will work with any phone using a 2mm charger jack.
"Bicycles are the most widespread means of transport in many markets around the world, so this is just one more benefit to be gained from an activity people are already doing," said Alex Lambeek, Nokia vice president in a statement.
Nokia said charging times will vary by speed but a cyclist completing a 10 minute journey at 6mph (10 km/h) will produce enough power for 28 minutes of talk time or 37 hours of standby time.
Also included in the kit with the dynamo is a holder to secure a phone to a bicycle while it is being re-charged..