I Built An E-Bike Entirely Out Of Trash

Those of us who are perpetual tinkerers know that sometimes we find projects and sometimes projects find us. The Trash-E-Bike, aka the IEB (Improvised Electric Bike) was a project of the latter sort. I never asked myself, “Can I build an e-bike out of trash?,” and though I eventually answered that question in the affirmative, the project was not especially planned. Instead, the IEB grew, bit by gathered bit, not unlike fast food wrappers and discarded plastic bags collected against a chain link fence by an afternoon breeze.

As a bicycle enjoyer, I find myself riding along LA’s urban rivers all the time (we have two besides the famously concreted LA River). In a city built around the automobile, the river paths offer a place where you can ride for miles and miles without ever encountering a car or a stop light, and, depending on which sections of the rivers you ride, you even get to experience a bit of actual nature in the form of herons, ducks, songbirds, rabbits, coyotes, turtles, and frogs.

Alongside that natural splendor are the many things cast off as useless by our society, three-wheeled shopping carts, half submerged vans, people with untreated mental illness, and bicycles in various states of disassembly (most of which have been left there by the homeless folks).

Last summer, when a friend of mine purchased a bare bicycle frame from Craigslist and told me he needed a fork and handlebars for it, I suggested we go down to the river and see what we could find.

Stubbed Toes And Incredible Bargains

Of the two rivers I live near, the Rio Hondo (Spanish for wide river) seems to be the better one for finding interesting discarded stuff. My friend and I rode our bikes down there, keeping our eyes trained on the brush and trees that line the river’s banks. We soon came upon a site with piles of bicycle and bicycle parts.

As we picked through the rusty, and sometimes burnt bicycle frames and parts, a man emerged screaming and limping from the nearby bushes. I didn’t know what else to do in the moment besides ask him if he was all right. He said he was and that he had just stubbed his toe while trying to jump across the river (in actuality, the Rio is not very Hondo). Then he called to another man living in a nearby tent, who emerged, shirtless and sporting a dark and gnarled scar that reached from his belly button to his breast bone.

I asked the scarred man if the bicycles and parts were his. He said no, but that they belonged to his friend, who lived a little further down the river but was away buying groceries. He asked if we were looking for something specific, and I pointed out a partially stripped Bridgestone frame we had been looking at and a large wire basket. He said we could have both for $5. What a deal!

Back at my place, my friend and I disassembled the bike frame and its fork from each other, and my friend left with the fork and handlebars. I was left with a frame I didn’t need and that was too small for me. I almost put it out on the curb for one of the junk men to pick up, but then I started to wonder if I could make the bike frame bigger. Inspired by a book given to me by a friend, I decided to give it a try.

The Incredible Expanding Bike Frame

If you look at bicycle frames, you’ll notice that most of them are built around a triangular core. That triangle can be made larger by increasing the length of each side, and if they are lengthened by the right amounts, the triangle’s three angles will remain unchanged. So, if I were to chop each side of the frame’s triangle in two and weld in some more tubing, I could make the frame whatever size I wanted it to be. I would never have the heart to do that to a nice frame, but for a dinged-up river frame that cost less than $5, why not give it a try?

My angle grinder made very quick work of the chopping, and some scraps of electrical conduit I had in my garage slip fit inside of the tubing that made up two sides of the triangle pretty well. The third side was made of wider tubing that didn’t match up with any of my conduit, so I went to the local scrap metal place. There, I found a piece of tubing that was the perfect diameter and it cost me a dollar and change. Total cost for the bike so far? About $6.25.

With some math, I figured out how long to make each side, and welded everything together. Just like that, I had a frame sized for me.

The River’s Bounty

Up to this point, I still hadn’t decided to build a bike. Expanding the frame had just been an experiment to see if I could do it, but then my friend gave me back the handlebars and fork. Now I felt like I should actually try to finish the bike, at least just to see if it was rideable. I went back to the scrap metal place for more tubing so I could extend the fork to match the now-bigger frame. Total cost: $8.25.

With project cars, it’s all the little pieces that end up costing the most (this is why I 3D printed parts for my truck). The same is true for bikes. I didn’t want to spend a lot of money on brakes, wheels, derailleurs, and all the other bits I would need to make the Bridgestone frame rideable. So, I went back down to the river. One day I found a rear wheel, but its bearings were seized.

Another day I found another rear wheel of the wrong size with good bearings. I swapped the good bearings into the other wheel, and now I had a rear wheel for my bike. On other days, I found a seat and seat post, a partially burned beach cruiser with a good set of handlebars and handlebar stem, pieces of chain, brake components, and handlebar grips. Each in turn was added to the growing bicycle, which I had still spent less than ten dollars on. I wonder if Dr. Frankenstein felt this good building a human out of free parts.

A Big Find

The main piece I still needed to finish the bike was a front wheel, and for months, this eluded me. The bicycle graveyards had dried up. I considered just buying a wheel, but decided to be patient and see if one would turn up. I set the bike aside and put it out of my mind.

I was on a ride a few months later when I spotted a wheel lying in the dirt next to the bike path, not far from where the Bridgestone frame originally came from. It was not any ordinary wheel though. At its center was an electric hub motor.

I had considered building an e-bike more than once over the last few years, but the expense of the motor and battery had always put me off.

Since the motors are a big part of the cost of building an e-bike, I grabbed the wheel and rode home, doing my best to not crash while clumsily holding it with one hand and steering my bike with the other.

A Brief Explanation Of Brushless DC Motors

The wheel had been lying outside during a particularly rainy couple of weeks, so the first thing I did was open it up to see how it looked inside. Some water had gotten in, but not a lot, and there was only a tiny bit of rust. I left it to dry and began researching what I had.

At the center of the wheel was a 36-volt, 250-watt brushless DC (BLDC) motor coupled to a planetary gearbox. (I also happened to have a 36-volt battery that a friend scavenged from a rental e-scooter someone had left broken down near his house, so I was off to a good start.)

Some motors, like brushed DC motors, will just run when you connect them to a power source. These motors make use of a commutator, an electromechanical device that switches the path electricity takes through the motor’s windings as it runs. That switching action keeps the motor spinning by constantly moving the magnetic field generated in those windings. Commutators are old technology, dating back to the early 1800s, and they’re robust, but they also have drawbacks. The commutator is a source of friction that reduces the motor’s efficiency. It also creates noise, sparks, and ozone gas, and the carbon brushes that conduct electricity into the commutator wear out with use.

BLDC motors, which are now found not just in e-bikes and e-scooters, but also power tools and electric cars, eliminate those disadvantages by replacing the commutator with electronics that do all the work of switching the path electricity takes through the motor’s windings. BLDC motors are quieter, more efficient, and require less maintenance than their brushed counterparts. The electronics also operate more flexibly than a commutator, which makes it easier to change the speed the motor runs at, and even make the motor run in reverse.

E-bike controllers that include those electronics can be had as cheap as $11 on AliExpress, and e-bike and e-scooter parts are pleasantly standardized, so finding a controller that connected with both my battery and motor was easy. I opted to spend a bit more and got controller that came with a display and a wiring harness for $50, including tax. Total cost: $58.25.

A few weeks later, my package arrived, and, as promised, the controller neatly plugged into my motor and my battery. I twisted the thumb throttle and breathed a sigh of relief as the motor quietly whirred to life.

I had tires and tubes I had found by the river, but they were sketchy from laying out in the elements, so I went to my local bicycle shop and bought a new set of tubes and tires. At $80, this was the most expensive part of the build. Total cost: $138.25.

Trying And Naming The Bike

I was excited to try out my new e-bike, but I didn’t have a good way of attaching the battery to the frame. For a test ride, I strapped the battery, housed in a 4-inch drain pipe, to the bike with bungee cords. When I posted a picture of the bike on my socials, friends joked that it looked like a suicide bomber’s bike, and said not to leave it unattended or someone would call the bomb squad. My brother dubbed it the Improvised Explosive Bike, or IEB, and I started calling it the Improvised Electric Bike.

Tidying up the wiring with some 3D-printed pieces and some hose clamps made the bike look a lot less like a threat to public safety, and cost me another $4. I couldn’t find a decent set of shift levers along the rivers, so I bought a set for $12 on eBay. Total cost: $154.25.

At this point, the bike was basically complete, and everything felt secure enough that I felt comfortable taking out on a real ride, and the results were impressive, at least to me. On flat ground, the IEB is capable of going up to 22 miles per hour—faster than really feels comfortable to me— and that’s without me even pedaling. I think that’s pretty good for something made mostly out of scavenged parts.

Future directions

I will admit that I spent more money than I intended to on this project, but it still cost only about a quarter of what a used e-bike would cost, and only a small fraction of the price of a new e-bike, and it feels good to know that I sourced the majority of the bike from parts left to rust in the dirt and bushes.

I plan to continue making upgrades to the bike as I find other parts. The most recent addition is a set of wire basket panniers I welded together out of a smashed dog kennel that was lying on the side of the road. Total cost for that side-project: $3 for a bag of hose clamps.