I have access to a bike and I have small electronics. Sure, I have a solar charging panel for those things, but, a backup system is a good thing to have in storage. THis complete setup to the right is $158 plus shipping. It includes a stand to convert the bike to a stationary power generator!
The instructions for many kits online are free if you buy the kits, but thanks to You Tube, you can watch someone build a working model and decide if it is for you.
Jun 4, 2010 ... Using an alternator, mountain bike and an inverter, we build a bicycle generator, and make 110 volt electricity, run a human-powered 220 Watt
Since most plans show converting a bike into a stationary bike first, you might knock the cobwebs off your old exercycle and create some energy!