This is a project I've done for a festival two years ago. The project in a few words:
Bicycle on a stand, where the back wheel connected to an alternator which produces energy when the bicycles are in use. The energy was being used for:
Charging a lead acid 12V battery.
Lighting a massive (~300) WS2812 RGB led strip.
Charging your phone.
Turning on a fan in the front.
Activate an Arduino and 4-digit 7-segment in the front which shows a timer and your speed.
Extra feature: On the back wheel there was also another Arduino with 4 RGB strips which change their color according to the wheel speed
This is pretty much how it looked like in the festival:
More videos, photos and description in my blog