There's a few instructables and other pages in a google search of "simple bike generator"--do any of them help?
https://www.google.com/search?q=simple+bike+generator&ie=utf-8&oe=utf-8
There are also threads:
https://endless-sphere.com/forums/search.php?keywords=bike+generator&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
Using "bicycle" instead of "bike" in the above searches finds other stuff that might help.
After you look thru those, If they aren't what you're after, perhaps post a complete list of the specifics of exactly what you want it to do, and what you have available that you'd like to use for it, and someone can help you figure out if you can do it without buying other things, and/or what you would ahve to buy to do it.