Eddy Current-generating disc
The gearless magnet bike is an experimental bicycle that replaces the traditional gear system with a magnetic clutch. The magnetic clutch is made up of two discs, one made of copper and the other made of aluminum, with magnets mounted on the aluminum disc. The copper disc is stationary and acts as the brake rotor, while the aluminum disc is connected to the pedals via a chain and rotates when the pedals are turned. The magnets on the aluminum disc generate eddy currents in the copper disc, creating resistance that can be used to control the speed of the bike.
Engineer/Youtuber Tom Stanton describes the process of designing and building the magnetic clutch, including selecting the best materials for the discs, determining the number and orientation of magnets needed, and designing and 3D printing the components. The final version of the clutch includes 200 magnets on the aluminum disc and requires a larger sprocket on the front to increase the gear ratio and generate more torque.
The magnetic clutch has some advantages over traditional gear systems, such as no contact friction, which saves on brake pads. However, it also has some limitations, such as the wasted heat energy that makes it harder to ride and has no advantages over a direct chain drive when climbing hills. Overall, the gearless magnet bike is an interesting experiment in using magnetic technology in bicycles and may inspire further innovations in this area.