of between 60 and 240 flashes per minute. National cyclists' organisations such as LAB (US) or CTC (UK) are a source of lighting information. Safety The use of lights for night riding is generally recommended or required by authorities as a basic safety precaution, even in a well-lit urban context. show a correlation between collisions and failure to use lights even during daytime. In countries where bicycles are used widely for commuting and short trips, such as the Netherlands and Scandinavia, bicycle head- and tail lighting regulation is strictly enforced by the authorities. However, a study from 2013 shows that different lighting regulations seem to have little influence on bicycle accident rates, and points out a lack of studies into the safety benefits of bicycle lighting. Front lighting White LEDs are available with output ranging from a few lumens to high-powered units producing about as much light as an automotive headlamp, suitable for high speed use on unlit trails. LED systems often include an option to dim the LEDs, or to provide a flashing light. Low-cost battery lights can be a good choice for occasional use, and usually meet legislative requirements. However, regular bicycle commuters would probably find it cost-effective to use rechargeable cells. Some headlamps use lithium-ion rechargeable battery packs, which may be recharged from a USB port. Flashlights Flashlights, although not specifically designed for bicycle use, are a viable alternative. They can be fastened to the bicycle handlebars with various mounting devices such as a lock-block. The round light pattern of a general purpose flashlight is inferior to the beam of a bicycle headlamp properly shaped to illuminate the roadway and not provide excess glare to oncoming traffic. Rear lighting Most LED lights will work in either flashing or steady modes. Some LED lights have multiple banks of LEDs allowing both flashing and steady light at once. This can also be achieved by having one flashing light and one steady one. In many countries, LED flashers are the norm for rear lights. In others such as Germany and the Netherlands flashing lights are forbidden by law. In the UK flashing LEDs (front and rear) are legal from October 2005, provided that the lights conform to the requirements of the current Road Vehicles Lighting regulations. Many vendors claim EU compliance, however, this provides no consistent safety or legal value across the Union. The most common power source for rear