One of the problems with using your smartphone as a GPS navigation or music system while out and about on your bicycle is the fact that you don’t have a charge point handy, as you do in a car. Instead you’ve just got to hope that your journey is not too long so you don’t run out of charge mid-way. Well now there’s a solution that’s pretty clever.

This Bike Dynamo Charger helps to remove that range fear, by offering a full USB charger for your phone which works from the back wheel motion. The device attaches to the rear wheel via a simple clamp system, and comes with a free handlebar mount to hold your handset. The device weighs just 180g, and outputs standard 5V USB power, and there’s a short USB cable included with a female end, so you’ll need to supply your own USB cable to connect up your phone.

The product is available in four delicious colors to match your bicycle decor, but one thing you have to remember is you’ll need to be cycling along at a speed of at least 12km/hour (around 7mph) to get the charger doing its job for your phone. For peak power you’re looking at 18mph, so step lively. The whole thing is priced at $47.95.