There will be LEDs because everything is better with blinky!

LEDs powered by a dynamo are really special. http://pilom.com/BicycleElectronics/DynamoCircuits.htm

Dynamo notes:

Brightness is commonly described in two different units of measure: lumens and lux. While battery-powered lights are commonly rated in lumens, dynamo lights are more often rated in lux. Whereas lumens are a measure of the total amount of visible light emitted from a source, lux is a measure of the intensity of light in the usable portion of its beam pattern. This means that two lights with identical lumen ratings can have very different lux measurements, depending on how the light is focused.