I’m a cycling enthusiast, and when the weather is bad, I use a bicycle trainer in my apartment. But riding to nowhere can feel pointless. That got me thinking about how I could use my cycling to produce electricity. By driving a generator with the movement of the back wheel, I figured that I could run a lamp or charge my phone. Realistically, this wouldn’t do much to cut my utility bills (or carbon emissions), but it would give my indoor riding a sense of purpose. Besides, I was curious to see what the project involved.
What I did was use the bike’s 24-volt, 200-watt electric motor for the generator portion of my electric bike conversion instead of doing mechanical work. I then used the bike’s 12-volt lead-acid battery to charge a state-of-the-art inverter. Finally, I had enough parts to power anything you’d normally plug into a wall outlet and also have enough power stored to power appliances when not pedaling.
When I saw the interesting tutorials that Instruct, a project-sharing social community on the Internet, had to offer, I thought it would be a clever way to create projects with my colleagues at an educational startup. The maker and educator Saul Lopez developed the concept during his internship with an environmental technology company in Los Angeles. “The exercise component was what made the project engaging,” he says. Plus, he adds, “I like that the project has a lot of room for customization.”
I designed my own bike by combining a conservative and modern design by utilizing a fixed-gear and single speed. On the left side of the wheel I combined the fixed-gear cog with a freewheel, allowing me to use them together during difficult pedaling turns while at the same time allowing me to keep going forward in an easy turn. On the right side of the wheel I attached another freewheel that doesn’t work unless I’m completely coasting my wheels or turning off my front wheel to stop.
To keep the bike steady, I dedicated a bicycle trainer to the project. A bike trainer is helpful because you can easily detach your bike from it if you want to go for a ride. However, you can also build your own stand and just need a setup that allows the rear axle to spin freely while raising the back wheel slightly off the ground. To prepare for using the bicycle stand as an electric generator, I removed the resistance unit, which is a spin metal cylinder that rubs against the wheel to generate a force on it similar to riding on pavement.