Never mind the mains, if you want to keep your mobile phone going for longer, get on your bike.That's the thinking at Nokia, which has produced a charging kit that uses a dynamo powered by a bicycle's wheels. If you can keep a steady speed of 4mph, your phone will keep charging. Or if you really want to go for it, 10 minutes of cycling at a constant 6mph will produce enough power for 28 minutes of talk time or 37 hours of standby time on your average Nokia handset.It's not clear as yet whether Nokia will market the set, which also includes a secure holder for your phone, in the UK, although for green reasons, we can't see why not. Saying that, the company has mentioned going worldwide, but initially, it's being pitched at countries where cycling is them ost common form of transport, working 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 Nokia vice president Alex Lambeek.Price? Well, that is almost certainly going to be country-specific, but as an initial guide, it will go on sale in Kenya soon for the equivalent of £12.50. Hopefully we will see it here by the end of the year. Which unfortunately misses the summer market.