Yes, it is actually possible to build an electric bike for under $100. The secret to doing this is... get most of your materials for free! Now I am not just going to turn you lose and say go find this stuff either. There are a few tricks and tips that I will give you and places to look. In addition, you will need to have problem solving skills of your own, since everything you get will probably be a little different from what I have. Undertaking this project is going to be challenging, and if you do not have substantial knowledge of machining tools, you might as well back out now. However, if you know your way around a lathe and are handy with only a few simple tools, this project is something you can complete in a few months working in only your spare time. This is also my entry into the Epilog Laser Cutter challenge, so please do not forget to rate and vote! Also, if you have any suggestions on things I can add to make this better, PLEASE comment, as I will be handing this in for a very important grade (basically my whole 4th quarter grade) so any criticism and help would be greatly appreciated! Thanks!
Step 1: Background and Theory
Before we dive into the instructions, I will need to give you a little background on this project. As a senior in High school, we are required to do a "senior project" that includes writing and presenting a research paper over a topic of your choosing. Included in this research paper must be an observation, or an essay about a hands-on experience you had regarding your topic. The requirements are simple: the topic must be school appropriate and you must show both foreknowledge and a significant learning stretch. Electric bike conversion was the perfect topic for me, because I have already successfully built a friction drive electric bike, but my previous attempts with chain drives have failed, so obviously I had to come up with a plan to successfully build this thing, so first I took a look at where my first attempt was unsuccessful, and it was pretty obvious. My first attempt at building a motorbike found me not paying attention to tolerances. I was just guessing when sprockets aligned and welding them onto what looked like the center of the shaft! Ouch! There was no way that was going to work. In addition, the shaft on my motor was very small, and trying to attach a sprocket to that would not have worked anyway. Therefore, I needed a way to drive the rear wheel (using the standard rear cassette) from the motor. My solution was a belt drive. So then, I wondered how to convert the belt drive to a chain drive to drive the rear wheel. The answer to that was a (not so simple) jackshaft that will mount in the bottom bracket perfectly aligning the drive sprocket and the driven sprockets. To make this project work I also knew that there would be no more welding on of sprockets, so instead I opted for a much more accurate (and better anyway) pinning method. In addition, my first bike, with a measly top speed of 20 MPH, left quite a bit to be desired. Therefore, I wrote a formula to calculate gear ratios, and decided to gear my bike for a top speed of 40 MPH! Finally, I had to find a way to get all of these parts with very tight tolerances. To answer this question: I simply had to machine them, and machine them very accurately. Accuracy is the key to being able to make this project work. Without a metal lathe, this project would be impossible to pull off. Now, with enough background information, it is time to continue to my senior project: convert a normal bike to a powerful electric motorcycle! (For under $100)