# You Can't Buy Wireless MTB Brakes—So I Made Them! Source: https://www.youtube.com/watch?v=-JBEq6XfkVI Recap page: https://rapidrecap.app/video/-JBEq6XfkVI Generated: 2026-08-28T07:03:29.935+00:00 --- ## The Gist A custom wireless mountain bike braking system called Airlock successfully functions using a door lock actuator, an ESP32 microcontroller, and a digital rotary encoder. Despite working on the trail, the system introduces major safety liabilities and requires a smartphone app to authenticate and process stops. ## Quick Overview Wireless mountain bike brakes do not exist on the market, so the host sets out to engineer a working prototype named Airlock. The build combines 3D printed housings, RC car batteries, a step-down buck converter, a MOSFET, and an ESP32 controller to actuate a mechanical brake caliper via a handlebar lever. After overcoming technical hurdles like cold solder joints and slow release times, the system successfully stops the bike during trail testing, complete with digital anti-lock braking features and a satirical subscription app model. **Key Points:** - The host designs Airlock using a car door lock actuator and a 3S RC car battery to pull the mechanical brake caliper wire. - An ESP32 microcontroller communicates wirelessly with the handlebar controls to process brake commands with low latency. - A rotary encoder functions as the handlebar lever, translating user rotation into digital inputs that control braking force curves. - A MOSFET acts as the high power switch, allowing the tiny microcontroller to command the heavy electrical draw of the actuator motor. - Trail testing proves the wireless braking system functions, allowing the host to ride down dirt paths and bring the fat bike to a stop. - Advanced software features include an anti-lock braking system adjustable from 1Hz up to high frequencies, and a derp setting to ignore initial lever pull slack. - A satirical smartphone app accompanies the setup, locking braking functionality behind a sign-in wall and offering a $9.99 monthly subscription called Airlock Max. ![Screenshot at 13:14: The custom 3D printed actuator housing mounted on the front fork pulls the mechanical brake cable to stop the wheel during bench testing.](https://ss.rapidrecap.app/screens/-JBEq6XfkVI/00-13-14.jpg) **Context:** Mountain bikes feature multiple forms of wireless technology for shifting and dropper seatposts, but braking has remained strictly hydraulic or cable-driven due to severe safety risks. Exploring what a wireless braking setup would entail, the host builds a complete prototype from scratch in his workshop. ## Detailed Analysis To build a wireless mountain bike brake from scratch, the host starts with a mechanical disc brake caliper and a car door lock actuator to pull the cable without hoses. He powers the actuator using a 3S LiPo RC car battery and builds a custom circuit board featuring an ESP32 microcontroller and a MOSFET to handle the electrical load. For the handlebar interface, he builds a custom lever using a digital rotary encoder to give the rider a light, click-based feel that sends wireless commands to the actuator. After fixing a cold solder joint on the circuit board that caused early power failures, the system successfully engages and locks the front and rear wheels during test rides. The accompanying software includes custom curve equalization, adjustable anti-lock braking frequencies, and a satirical subscription app required to sign in and authorize stops. ### Designing the Actuator and Power System The core mechanical challenge is finding a component strong enough to pull a brake cable without hydraulics. - A car door lock actuator provides cheap and powerful linear motion, operating on a single polarity to push and pull. - A 3S 11.1-volt RC car battery supplies the necessary power to drive the actuator motor through an inline fuse. - An LM2596 buck converter drops the battery voltage down to 5 volts to safely power the microcontroller components. ![Screenshot at 01:52: The car door lock actuator is tested with an individual battery lead to verify its linear pushing and pulling movement.](https://ss.rapidrecap.app/screens/-JBEq6XfkVI/00-01-52.jpg) ### Building the Handlebar Lever and Electronics The handlebar control needs to feel natural while sending precise digital signals to the brake unit. - A rotary encoder functions as a digital volume knob, providing a lightweight lever pivot point with distinct clicks. - An ESP32 microcontroller runs the firmware, communicating with the actuator and handling wireless commands with low latency. - A MOSFET functions as a power gate, allowing the low-power microcontroller commands to safely drive the high-amp actuator. ![Screenshot at 04:33: The rotary encoder board used for the handlebar lever provides digital input steps as the rider pulls the brake.](https://ss.rapidrecap.app/screens/-JBEq6XfkVI/00-04-33.jpg) ### Bench Testing and Troubleshooting Early prototypes suffer from wiring failures and sluggish release times that require workshop intervention. - A cold solder joint on the circuit board causes the system to intermittently lose power during initial bike mounting. - The release speed of the actuator is initially too slow, prompting software adjustments and better spring tensioning. - A 3D printed enclosure houses the battery, buck converter, and microcontroller neatly on the front fork. ![Screenshot at 09:05: The host reconnects loose electronics and checks solder joints with a multimeter after the system fails on the repair stand.](https://ss.rapidrecap.app/screens/-JBEq6XfkVI/00-09-05.jpg) ### Trail Testing and Software Features Once operational in the workshop, the bike heads out to real dirt trails for performance evaluations. - The system successfully stops the bike during real trail rides, proving that wireless braking is technically functional. - A braking bias feature allows the single handlebar lever to control the front and rear actuators simultaneously with customized force ratios. - Software settings include an adjustable anti-lock braking system that pulses the brakes at specific frequencies when fully pulled. ![Screenshot at 19:41: The host test rides the custom wireless-braking mountain bike down a dirt trail and successfully comes to a stop.](https://ss.rapidrecap.app/screens/-JBEq6XfkVI/00-19-41.jpg) ### The App and Safety Features A satirical software ecosystem rounds out the build by locking basic functionality behind a subscription paywall. - A smartphone app requires riders to sign in with an Airlock ID and an active subscription balance in order to brake. - A feature called Coaster Lock acts as a fail-safe, allowing the rider to kick their foot backward on the pedals to engage the rear brake if wireless connectivity fails. - The subscription tier Airlock Max costs $9.99 a month and unlocks weekend braking privileges alongside anti-theft immobilization. ![Screenshot at 15:13: The smartphone app interface displays battery percentages, braking analytics, and subscription status reminders.](https://ss.rapidrecap.app/screens/-JBEq6XfkVI/00-15-13.jpg)