I hacked into the worst e-bike and fixed it [video]

TL;DR: The author reverse-engineered, cracked the Bluetooth, and built a custom screen to repair and upgrade a broken Revo hubless electric bike with cracked plastic shells, turning it into "the world's best worst bike." ## Background: The Worst Electric Bike Ever The Revo hubless bike has been described as "the world's worst electric bike." It has a laundry list of problems: disintegrating plastic body, self-destruct mode (unintended acceleration), and most features relying on a now-defunct smartphone app—rendering the wheel lock, headlight, etc., completely useless. The author borrowed this Revo from viewer Brian and set out to fix it piece by piece. ## Teardown and Circuit Board Exploration ### Finding the Brain The author tore off the plastic shell and found a "rat's nest" of wiring and the main circuit board (the brain) inside the motor housing. The ESC (electronic speed controller) was hidden under a metal plate; another board handled all other functions. After unplugging 14 harnesses, the author was surprised to find that every connector on the board had numbered ends (e.g., "14") and all components were labeled in English—silly design, but the electrical engineer had put in good effort. These labels also made reverse engineering much easier. ### Grabbing Serial Data The author used a 4-wire cable to keep access to the board and set up a temporary lab, using CoolTerm for serial communication. Eventually, data appeared—"Revo ready" showed up on screen—but that alone wasn't enough to get useful info. ## Cracking the Bluetooth Password ### Discovering a Password Reset Vulnerability Everything on the Revo relied on the Bluetooth app. Every Revo shipped with a default password (six 1s), but once paired with the app, the password was changed, and the only way to reset it was via the app (now dead). The author accessed the BLE chip, and when attempting to connect with a wrong password, the real Bluetooth key appeared in the serial output: **696969**. This was a security hole—physical access via serial allowed reading the plaintext password. ### Understanding the Protocol After connecting over Bluetooth, the author used a laptop terminal to log the Bluetooth controller's output. By pressing buttons, squeezing brakes, twisting the throttle, etc., they collected a ton of status update data. Later, an old Revo Android app was found online; the author had Claude decompile it and search for command strings. For example, "set headlight on" corresponded to command "C14". The author successfully sent commands to turn the headlight on/off and even control the kickstand servo—acquiring the full protocol list. ## Building a Custom Screen ### CYD (Cheap Yellow Display) The author used a microcontroller (CYD, ~$22) with Bluetooth, Wi-Fi, and UART as the screen the Revo should have had from the factory. With help from Claude to write code, real-time monitoring and control were achieved: showing speed, battery level, assist mode, turn signal status, headlight toggle, badge light (blue Beno badge) control, etc. The screen can display self-destruct mode warnings (if assist is on, the bike might run off when pushed) and kickstand ejection warnings. ### Improving the Badge Light The original badge light used an EL (electroluminescent) panel which required a high-voltage transformer and produced an annoying buzz. The author removed the transformer and replaced it with a 12V LED strip, directly connected to the bike's 12V circuit—eliminating the noise and making it easier to drive. ## Other Fixes ### Reassembling the Plastic Shell The copper inserts on the clamshell housing easily cracked and fell out. The author measured and 3D-printed adapters, glued them into the broken mounting holes, and reassembled everything—resulting in a very sturdy fit. ### Brakes and Grips Upgraded brake pads; cleaning didn't fix the slippery grips, so new grips were installed. ### Hole in the Rear Fender Covered with yellow reflective tape to match the existing tape on the wheel. ### Kickstand The loose kickstand was bent back into shape and re-secured with generous amounts of Loctite threadlocker. ### Final Cleanup and 3D-Printed Mount Cleaned off adhesive residue from the plastic body and applied band-aids to hairline cracks. Designed and 3D-printed a more suitable sunshade and mount for the screen (using high-strength material). ## Final Delivery and Demo The bike was fully assembled, and the author showed Brian the results: the screen displayed real-time speed, battery, assist level (Eco to Turbo); turn signal arrow icons; headlight icon changing state; and the Beno badge light controllable. The screen also added warnings: "If pedal assist is on, the Revo may run away" and "Ejector is active." The custom screen solved all the features that had been rendered useless by the missing app. Source: https://www.youtube.com/watch?v=hPrtVGimBYs