/cdn.vox-cdn.com/uploads/chorus_asset/file/24827398/Close_up_motor.png "Lessons Learned from Converting a Cargo Bike into an E-bike")
For approximately seven years in my 20s, in the midst of a personal crisis, I abandoned my nerdy interests and took up a new hobby: cycling. Little did I know that this hobby would eventually become a lifestyle for me. During this transformative period of my life, I made several changes. I sold my extensive collection of game consoles (a decision I now regret), stopped buying computers, got rid of my car, and left my data aggregation job to pursue a career as a pedicab driver. This gig job was something I took on before gig jobs became popular, and it eventually led me to become a guide at a small bike tour and rental company.
One of my responsibilities at the bike tour company was bike maintenance. Our mechanic taught me some useful tricks, such as wheel truing and bike building basics. Although I wouldn’t consider myself a professional bike mechanic, I became comfortable with the basics of bike repair.
One day, a retiree who enjoyed showing off his toys brought in a Copenhagen Wheel—a self-contained e-bike kit that houses the batteries and motor within the rear wheel hub. When he let me ride it, I was amazed by the extra boost of acceleration in each pedal stroke. This experience completely changed my skeptical mindset.
A few years later, I was fortunate enough to acquire my own e-bike. I found them to be incredibly fun and convenient, and for some people, they can even serve as a complete or partial replacement for a car. E-bikes are particularly suitable for quick trips as they are easier to park. Plus, if the battery runs out, you can still ride a heavy bicycle.
While an electric cargo bike is an even better car replacement, the high cost was a deterrent for me. However, an unexpected opportunity came my way, and I couldn’t pass it up.
Recently, a friend who works for a nonprofit bike company in Chicago called Working Bikes offered me a 1,000W Bafang motor in exchange for my partner’s rarely used e-bike. This allowed me to convert the cargo bike she preferred to ride, and the bike shop could easily sell the e-bike. I initially thought this conversion would be a quick two-hour job, but I soon realized how flawed that assumption was.
The conversion process required various tools and parts, such as a battery charger, connection cables, speed sensor, battery bag, and bottom bracket wrench. Other items included the Bafang 1000W motor, battery, grips with a twist throttle, zip ties, chainring, rubber shims, screw clamp, brake levers, crank arms, motor mount, bottom bracket locknuts, sealed bottom bracket tool, crank puller, chainbreaker, 15mm wrench, e-bike display, and Polylube.
My partner had purchased a 2015 Xtracycle Edge Runner 24D cargo bike, which was highly regarded in my hipster circle during that time. While it was a nice bike, it wasn’t designed for speed, and the basic components needed to be replaced. Since I had to work on the bike anyway, I decided to electrify it by adding a motor.
E-bikes typically come with two types of motors: mid-drive and rear-drive. Front-drive motors exist but are not as common. The Bafang motor I acquired is a mid-drive motor.
Despite encountering a few surprises along the way, the conversion process went relatively smoothly considering my level of experience. In the end, I successfully created a functional electric cargo bike. While I primarily worked on a cargo bike, the basic parts of a bicycle remain the same, just spread across a longer frame.
The most significant part of the conversion process involved mounting the motor, which was relatively straightforward. I had to remove the crank arms, front chainring, and bottom bracket using specialized tools like a crank puller and bottom bracket tool, along with various hexagonal wrenches.
The crank puller was particularly interesting. It consists of two parts—an outer bit that threads into the crank and an inner shaft that pushes against the bike as the handle is spun, allowing the crank to be removed. This tool provides a mechanical advantage.
After removing the bottom bracket, I cleaned the old grease from the frame’s shell, which is where the bottom bracket slots in. Once cleaned, I greased the motor’s bottom bracket shaft and inserted it into the shell from the drive side of the bike.
Securing the Bafang motor involved using a small bracket, a locknut, and an outer locknut. I initially didn’t tighten the inner locknut enough, which caused the motor to be loose when I test-rode the bike. I had to go back and tighten it further.
Next, I installed the speed sensor, which required attaching a magnet to a spoke and fixing a sensor to the frame. This sensor provides the necessary information to the motor’s controller to determine speed and engage the motor. Due to the cargo bike’s unique frame, finding a suitable spot for the sensor was challenging, but I managed to make it work.
Unfortunately, I encountered a setback when I realized that the cable connecting the speed sensor to the handlebar-mounted display was too short. I had to order an extension cable, which caused a delay in completing that part of the job. However, I was still able to install the new grips with a twisting throttle and attach the display without any issues.
Another obstacle I faced was the integration of the cargo bike’s existing shifter and brake. Since the new brake lever included with the motor served as a kill switch for the motor, I couldn’t continue using the old shifter. This meant I had to replace the shifter, rear derailleur, and cassette, which needed to be changed anyway.
Due to a mishap with my bike repair stand tipping over, I lost the master link for my chain. After spending a considerable amount of time searching for the missing piece, I decided to give up and buy a replacement at a local bike shop. Looking back, I realized that I didn’t actually need to break the chain for this particular job.
On the second day of the project, things went much smoother. I replaced some cables and cable housing, reassembled the bike’s drivetrain, and performed final adjustments to get the bike ready for a test ride. However, I noticed a strange noise during the test ride. I couldn’t initially determine the cause but suspected it might be the kickstand or the motor not being securely tightened.
Despite a few challenges and setbacks, I managed to successfully convert the cargo bike into a functional electric bike. This project taught me valuable skills and allowed me to enjoy the benefits of a versatile and eco-friendly mode of transportation.