Tom Stanton 3D Prints an eBike Conversion Kit — "Without Any Electronics"

Maker Tom Stanton has built a custom electric bike with a difference: though it includes, as you'd expect, a battery and a motor, it lacks anything in the way of "electronics" — or, rather, modern integrated circuits.

"Have you ever wondered if it's possible to build an electric bike without any electronics," Stanton asks by way of introduction to his latest project. "Now, what I mean by 'no electronics' is by following the definition according to Google, where 'electronics' are 'the branch of physics and technology concerned with the design of circuits using transistors and microchips' — we still need to use some wires and a battery, but I want everything else to be mechanical."

The process of building an electric bike usually begins with a brushless DC motor and a battery, but there's an immediate problem for Stanton's mission: such motors require an electronic speed controller (ESC), which most definitely breaks even a generous reading of the "no electronics" rule. The solution: a custom 3D-printed reed-switch motor, trialled on a small scale with a toy car before being sized up for use on a full-scale bike.

"An off-the-shelf reed switch can't handle more than about half an amp," Stanton admits," so I've had to make my own supersized reed switch. It's very simple, with just two metal strips separated by a small gap — just like the small reed switch — and when the magnet passes it one of the strips is attracted towards the other and applies power to the coils."

A further modification to the design, switching the custom motor to a Halbach array to boost the output to the point where it could feasibly deliver enough push to make a difference while employing tungsten rods as contacts in the reed switch to prevent burnout. The motor was then attached to an off-the-shelf tubular bike frame using a custom-built 3D-printed mount, with a 3D-printed sprocket connected to the wheel then the motor via a toothed belt.

An analog dial on the handlebars allows the battery's charge level to be monitored, while two controls deliver the ability to vary the power of the motor's output or switch it to a regenerative mode — charging the battery as the bike's wheel turns.

The project is documented in full in the video above, and on Stanton's YouTube channel.