How to Safely Disable the Speed Limit on Your Mountain E-Bike

I have to say this before we touch a single wire: unlocking your e-bike changes its legal classification. In most places, a bike that assists past 20mph (or 25km/h in Europe) is legally considered a moped or motorcycle. If you ride it on public streets or shared bike paths, you can face massive fines or have the bike impounded. Furthermore, altering the controller or using a tuning chip will instantly void your manufacturer's warranty. If your motor burns out next week, you are paying out of pocket. Only do this if you intend to ride on private, unrestricted off-road trails.

This is the oldest trick in the book, and it doesn't require buying any extra parts. Your bike's computer calculates your speed by counting how many times the rear wheel completes a revolution. If you go into your LCD display's hidden settings menu (usually accessed by holding down the 'Up' and 'Down' buttons simultaneously for three seconds), you can change the programmed wheel size. Tell the computer you have tiny 16-inch wheels instead of your actual 29-inch wheels. The bike will now think you are going much slower than you actually are, effectively raising the speed limit before the motor cuts off.

Changing the wheel size throws off your speedometer and odometer permanently. If you want a clean, professional solution, you need a 'tuning chip' (like SpeedBox or PearTune). These are tiny microchips that plug directly into the wiring harness between your motor and your speed sensor. You have to remove the plastic casing around your bottom bracket to install them. The chip intercepts the speed signal, halves it, and sends the fake slower speed to the controller. This tricks the motor into assisting you all the way up to 30mph or more, while some premium chips will even calculate the math to keep your speedometer accurate.

If you don't want to mess with settings or buy a $150 chip, there is a physical workaround for bikes with external spoke magnets. Your bike calculates speed using a magnet on the rear wheel spoke that passes a sensor on the frame. If you take that magnet off the spoke and zip-tie it to your pedal crank arm, and move the sensor to face the crank, the bike will now measure your pedaling cadence instead of your wheel speed. Since your pedals spin much slower than your wheels, the bike thinks you are going incredibly slow, and the motor will never hit the cutoff limit.

Now that you have unlocked the motor, you need to understand that you are pushing it harder than the engineers intended. Running a motor at maximum assist at 28mph up a sustained fire road generates a massive amount of heat. Because you bypassed the limiter, the bike won't force you to slow down. You have to be the adult in the room. If you smell burning electronics or the motor casing feels too hot to touch, stop and let it cool down. A fried stator will cost you more than the bike is worth.