E-Bike Speed Unlock Guide: How to Remove Speed Limiters by Brand & Model

If you’ve hit the 20 mph ceiling on your electric bike and want to go faster, you’re not alone. Most e-bikes sold in the US come with a factory speed limiter to comply with federal and state laws, but many riders want to know if and how they can remove it. This guide breaks down speed unlock options by major brand, what’s actually involved, and the legal and mechanical trade-offs you need to weigh before you start changing settings.

Why E-Bike Speed Limiters Exist (And What They Actually Do)

The speed limiter isn’t a single part — it’s a combination of software and hardware working together. On most e-bikes, the controller reads wheel speed from a sensor (either a magnet on the spoke or a sensor inside the motor) and cuts motor power once you hit a preset threshold. That threshold is usually 20 mph for Class 1 and Class 2 e-bikes, and 28 mph for Class 3 models.

The limiter only affects motor assistance, not your ability to pedal faster. If you’re on a downhill, you can exceed the limit under your own power — the motor just stops helping. This distinction matters because unlocking the speed limiter doesn’t make the bike physically capable of more; it changes how long the motor keeps pushing.

The trade-off is real: every mph you add increases aerodynamic drag exponentially, not linearly. Going from 20 mph to 28 mph requires roughly double the motor output, which means your battery drains significantly faster. A bike that gets 40 miles of range at 20 mph might only get 25–30 miles at 28 mph.

Brand-by-Brand Speed Unlock Methods

Bosch

Bosch is the most common mid-drive motor system on premium e-bikes, and it’s also one of the most locked down. The speed limit is stored in the motor controller firmware, and you can’t change it through the display or a simple app.

What works: The only reliable method is a speed box (also called a dongle) that plugs between the motor and the display. These devices intercept the wheel speed signal and send a modified signal to the motor, tricking it into thinking you’re going slower than you are. Popular options include the SpeedBox 2.0 and the PearTune. Installation takes about 20–30 minutes and requires disconnecting the display cable, plugging in the dongle, and hiding the unit in the frame.

What doesn’t work: There’s no software hack or app-based unlock for Bosch systems. The firmware is encrypted, and Bosch actively updates it to block known workarounds. If you take your bike to a dealer for service, they can detect a speed box and may void your warranty.

Rider outcome: With a speed box, a Bosch-equipped bike can reach 28–30 mph on flat ground, depending on the motor (Performance Line vs. Cargo Line) and your weight. Expect a 15–20% range reduction at sustained higher speeds.

Failure mode to watch for: The most common issue with Bosch speed boxes is intermittent cutoff — the motor cuts out briefly at random intervals, then resumes. This usually happens because the dongle’s signal isn’t perfectly synchronized with the motor’s speed sensor, especially on bumpy roads where the cable connection wiggles. If you feel surging or hesitation after installation, reseat both ends of the dongle connection and secure the unit with a zip tie so it can’t shift. If the problem persists after two attempts, remove the dongle and ride at the factory limit — a faulty signal can confuse the motor controller and trigger a fault code that requires dealer service to clear.

Shimano

Shimano’s STEPS system is the second most common mid-drive platform, and it’s slightly more accessible than Bosch. The speed limit is also in the firmware, but Shimano offers regional variations that some shops can flash.

What works: The most practical option is again a speed box — the PearTune and similar devices work with Shimano STEPS E6100, E7000, and E8000 motors. Installation is similar to Bosch: unplug the display cable, insert the dongle, and route the wiring. Some riders also report success with the Shimano E-Tube app for adjusting certain parameters, but the speed limit is not one of them — the app only adjusts assist levels and wheel size, not the cutoff.

What doesn’t work: Shimano’s newer EP8 and EP6 motors use updated encryption that makes third-party dongles less reliable. As of 2024, some speed boxes work intermittently with these motors, but firmware updates can break compatibility.

Rider outcome: Unlocked Shimano systems typically reach 25–28 mph. The mid-drive torque delivery means acceleration stays strong even at higher speeds, but the motor’s internal gearing creates more resistance when you pedal past the assist cutoff.

Failure mode to watch for: Shimano systems sometimes throw an error code (usually E010 or E043) after a speed box is installed. This is the motor controller detecting an abnormal signal pattern from the speed sensor. The fix is usually straightforward: power the bike off completely, wait 30 seconds, and power it back on. If the error returns within the first mile, the dongle is likely incompatible with your firmware version — check the manufacturer’s website for a firmware update or a different model. Riding with an active error code can reduce assist to a crawl, so don’t ignore it.

Bafang

Bafang motors are the workhorse of the DIY and conversion kit market, and they’re the easiest to unlock. Unlike Bosch and Shimano, Bafang uses open-source-friendly controllers that you can reprogram directly.

What works: If you have a Bafang BBS02 or BBSHD mid-drive kit, you can buy a programming cable (USB-to-UART) for about $15–20 and download the free Bafang Configuration Tool software. The software lets you adjust the speed limit, current limits, and throttle response. For hub motors like the Bafang G060 or G062, you can often change the speed limit through the display settings — many displays (like the DPC-18 or C965) have a hidden settings menu accessible by holding the up and down buttons for 5 seconds.

What doesn’t work: You can’t unlock a Bafang motor without either the programming cable or a display with accessible settings. If you bought a pre-built bike with a proprietary display, you may need to replace the display with a compatible one to access the settings.

Rider outcome: This is the most flexible option. You can set the speed limit anywhere from 15 mph to 40+ mph, but be realistic — a 750W motor will struggle to push you past 30 mph on flat ground, and a 500W motor will top out around 25 mph. The programming software also lets you tune throttle response and pedal assist sensitivity, which is a bonus if you want a more aggressive ride.

Verification step: After you change the speed limit in the Bafang Configuration Tool, save the settings and disconnect the cable. Take the bike for a test ride and pedal up to the old cutoff speed — you should feel the motor continue to assist past 20 mph. If the motor still cuts out at the old limit, the settings didn’t save properly. Reconnect the cable, open the software, and confirm the new speed value is still there. A common mistake is changing the value but forgetting to click “Write” before disconnecting — the software won’t save changes automatically.

Rad Power Bikes

Rad Power Bikes uses a custom controller with a proprietary display, and the speed limit is set in the controller firmware. The good news: Rad has historically left the speed limit accessible through the display settings.

What works: On most Rad models (RadRunner, RadCity, RadWagon), you can access the speed limit setting by holding the up and down arrow buttons simultaneously for about 5 seconds until the display enters the settings menu. Navigate to the speed limit option (usually labeled “SPd” or “Speed Limit”) and change it from 20 mph to 40 mph (the maximum the controller allows). This is a legitimate setting, not a hack — Rad includes it in the display firmware, though it’s not documented in the owner’s manual.

What doesn’t work: This method doesn’t work on newer Rad models with the updated display (RadRunner 2 and later). Rad has locked down the settings menu in recent firmware updates, and there’s no reliable third-party dongle for their proprietary connector.

Rider outcome: Unlocking a Rad bike to 40 mph doesn’t mean you’ll actually go 40 mph — the 750W geared hub motor will realistically top out around 25–28 mph on flat ground. The unlock just removes the artificial ceiling so the motor can keep pushing until it hits its mechanical limit.

Failure mode to watch for: If you change the speed setting and the display shows the new value but the motor still cuts out at 20 mph, the controller firmware may have a secondary limit that the display setting doesn’t override. This is more common on 2023 and later models. There’s no user-accessible workaround for this — the secondary limit is baked into the controller. Your only options are to accept the factory limit or replace the controller entirely, which costs $200–300 and requires matching the connector types.

Specialized

Specialized e-bikes use the Brose motor system (in the Turbo line) or the proprietary SL 1.1/2.2 motors (in the Turbo Vado and Como SL). The speed limit is in the motor firmware, and Specialized has been aggressive about locking it down.

What works: The only practical option is a speed box like the PearTune or the STUnlocker app. STUnlocker works via Bluetooth on some Specialized models — you connect to the bike’s display with your phone and change the speed limit through the app. This works on the Turbo Vado and Como models with the TCD display, but not on the SL models with the integrated display.

What doesn’t work: Specialized dealers cannot unlock the speed limit, and the company actively voids warranties if they detect tampering. The STUnlocker app costs about $30 and requires a compatible display firmware version.

Rider outcome: Unlocked Specialized bikes reach 28 mph on the Turbo line (which is already Class 3) and about 25 mph on the SL line. The SL motors are lower torque (35 Nm vs. 70 Nm on the full Turbo), so they run out of steam sooner at higher speeds.

Verification step: After changing the speed limit with STUnlocker, confirm the change by checking the bike’s status screen — the app should show the new cutoff speed. Then take a test ride and pedal steadily past the old limit. You should feel the motor continue to assist without a hard cutoff. If the motor cuts out abruptly, the app may have changed the display setting but not the motor firmware. Reconnect the app and check for a “write to motor” step — some models require a separate confirmation to push the change to the motor controller.

Aventon

Aventon e-bikes are popular budget options, and they use a mix of proprietary and generic controllers. The speed limit is accessible through the display on most models.

What works: On the Aventon Pace 500, Level, and Sinch, hold the up and down buttons on the display for 5 seconds to enter the settings menu. Navigate to “PAS” or “Speed” and set the limit to 28 mph (the maximum). The Aventon Aventure and Aventure.2 use a different display, but the process is similar — hold the power button and the up button simultaneously.

What doesn’t work: Aventon’s newer models (like the Level.2) use a locked display that doesn’t expose the speed setting. There’s no third-party dongle for Aventon’s proprietary connector, so your options are limited to replacing the controller and display entirely.

Rider outcome: Aventon bikes with 750W motors will reach about 28 mph unlocked, which matches their Class 3 rating on some models. The Pace 500 has a 500W motor and will top out around 24–25 mph.

Failure mode to watch for: The most common mistake with Aventon displays is changing the wrong setting. The settings menu includes both a speed limit and a wheel size setting, and they’re easy to confuse. If you change the wheel size instead of the speed limit, the speedometer will read incorrectly — it might show 28 mph when you’re actually going 22 mph, or vice versa. This also affects the motor cutoff, because the controller calculates speed from wheel rotations. If your speedometer seems off after changing settings, go back into the menu and verify the wheel size matches your tire (26″ for most Aventon models, 27.5″ for the Aventure). Reset it to the correct value before adjusting the speed limit.

Legal and Safety Considerations Before You Unlock

Federal and State Class Laws

The US Consumer Product Safety Commission defines three e-bike classes, and many states have adopted these definitions into law:

• Class 1: Pedal-assist only, max 20 mph
• Class 2: Throttle-assisted, max 20 mph
• Class 3: Pedal-assist only, max 28 mph

If you unlock a Class 1 or Class 2 bike to go faster than 20 mph, it no longer legally qualifies as that class. In states that require e-bikes to meet class definitions for road access, you could be riding an unregistered motor vehicle. Some states (like California) require a driver’s license and insurance for bikes that exceed class limits.

Warranty and Service Implications

Speed boxes and firmware modifications are detectable. Bosch, Shimano, and Specialized all have diagnostic tools that log motor usage data, including maximum speed. If you take your bike in for service and the dealer runs a diagnostic, they’ll see the tampering and can void your warranty on the motor, battery, and controller.

Stop and escalate threshold: If your bike is still under warranty and the motor or battery develops a fault within the warranty period, remove any speed box or revert settings before taking it to a dealer. If the dealer runs a diagnostic and finds tampering, they can refuse service entirely — not just for the motor, but for any component. If you’re unsure whether your modification is detectable, call the dealer before booking service and ask how they handle modified bikes. If the motor is making grinding noises, clicking sounds, or vibrating abnormally at speed, stop riding immediately and take it to a dealer — these symptoms can indicate internal damage that a speed box will make worse, and continuing to ride risks a complete motor failure.

Battery and Motor Stress

Running a motor past its designed speed limit increases heat generation. Mid-drive motors (Bosch, Shimano, Brose) are particularly sensitive because they push through the drivetrain, and sustained high-speed riding can overheat the motor and reduce its lifespan. Hub motors handle heat better but draw more current, which stresses the battery. A 48V battery at 28 mph sustained output can discharge at 20–25 amps, which is near the continuous rating of many budget batteries.

How to tell if you’re pushing too hard: Pay attention to how the bike feels on a long climb after you’ve unlocked it. If the motor starts to feel weak or surging on a hill that was easy before, the controller is likely reducing power to protect itself from overheating. This is called thermal throttling, and it’s a warning sign. If it happens regularly, the motor is working beyond its design envelope — you can either accept the reduced performance on climbs or revert to the factory speed limit. Continuing to push through thermal throttling can damage the motor windings, which is a repair that costs more than most speed boxes.

Brake and Tire Limits

Most e-bike brakes are rated for the bike’s class speed. A bike designed for 20 mph has brakes sized for that kinetic energy — at 28 mph, you have nearly double the stopping distance. Check your brake type: hydraulic disc brakes handle the extra speed well, but mechanical disc brakes and rim brakes (rare on e-bikes, but present on some budget models) may fade. Tires also matter — most e-bike tires are rated for 25 mph or 30 mph, and exceeding that rating risks a blowout.

Tools and Parts You’ll Need for a Speed Unlock

Depending on your brand, the unlock process requires specific tools. Here’s what to have on hand:

• For Bosch and Shimano: A speed box dongle ($50–120), a Torx wrench set (T20 and T25 are common), and zip ties to secure the dongle inside the frame.
• For Bafang: A USB-to-UART programming cable ($15–20), a laptop with Windows (the Bafang Configuration Tool doesn’t work on Mac), and a multimeter if you want to verify voltage.
• For Rad and Aventon: No tools needed for the display settings method — just your fingers and the button sequence.
• For Specialized: The STUnlocker app ($30) and a smartphone with Bluetooth.

While you’re working on the drivetrain, it’s worth checking your chain condition. Higher speeds put more torque through the chain, and a worn chain will skip under load. If your chain has more than 1,000 miles on it, consider replacing it with a model rated for e-bike torque. The KMC Unisex’s E10 EPT Chain is designed specifically for mid-drive motors like Bosch and Shimano, with higher torsion resistance to handle the extra stress.

For 10-speed drivetrains, the KMC X10 10-Speed X-Series Bicycle Chain offers a titanium nitride coating that reduces wear — useful if you’re planning to ride at sustained higher speeds. If you’re on a budget, the KMC Unisex’s X10 Chain is a solid entry-level option that’s compatible with all major 10-speed systems.

Deciding Whether to Unlock: A Practical Framework

Before you spend money on a speed box or programming cable, ask yourself three questions:

1. What’s your actual riding scenario? If you’re commuting on roads with 35 mph