You Can't Buy Wireless MTB Brakes—So I Made Them! | Berm Peak

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.

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.