Using a few easily accessible parts, you can make a bicycle generator that can power various electronic appliances, such as laptops and batteries!
24V DC scooter motor
DC-DC battery charger
A car battery, or something similar
Wires for electrical connections and various bike parts and tools.
A multimeter might be useful to check various voltage differentials between different objects.
The specific hardware we used:
Motor: 24V 300W Scooter Motor
Battery: 12V 18 amp-hr lead-acid battery model 7448k51
Charger: Thunder 620 battery charger- 300 Watt 20 Amp
Inverter: 400 Watt inverter Model 6987k22