E-Bike Speed Limiters & Derestriction: Legal Risks in Australia

Every e-bike sold in Australia has a speed limiter. The motor assist cuts off at 25 km/h — pedal harder than that and you are on your own. Some riders remove or bypass this limit. Here is what happens when they do.

Why the 25 km/h Limit Exists

Australian law (and European EN 15194 standard, which most e-bikes sold here comply with) defines a legal e-bike as:

• Maximum continuous motor power: 250 W
• Motor assist must cut off at: 25 km/h
• The rider must pedal for the motor to provide assist (pedal-assist, not throttle-only — with some state exceptions for low-powered throttles)

Above 25 km/h, you can still ride faster — the motor just stops helping. You pedal under your own power, same as a regular bicycle.

Why 25 km/h? It is a compromise between usefulness and safety. At 25 km/h, an e-bike travels at roughly the same speed as a fit cyclist on a regular bike. This means:

• Infrastructure (bike lanes, shared paths) is designed for this speed range
• Stopping distances are manageable with bicycle brakes
• Collision energy with pedestrians and other cyclists is within survivable limits
• The bike handles like a bicycle, not a motorcycle

How Speed Limiters Work

Software Limit

Most e-bikes use a software speed limit in the motor controller. The controller reads the wheel speed sensor and progressively reduces motor power as the bike approaches 25 km/h, then cuts it completely at or just above 25.

How it is bypassed:

• Derestriction dongles/chips: small electronic devices that plug between the speed sensor and the controller. They halve the speed signal — the controller thinks the bike is going 12.5 km/h when it is actually going 25 km/h, so it keeps assisting to 50 km/h.
• Magnet repositioning: some speed sensors use a magnet on the wheel spoke. Moving the magnet to a smaller-diameter part of the bike (e.g., the crank arm) makes the controller think the wheel is spinning slower.
• Firmware modification: flashing the motor controller with modified firmware that removes or raises the speed limit. Some manufacturers' diagnostic software can do this.
• Third-party apps: some Bluetooth-connected e-bike motors can be derestricted via smartphone apps that modify controller parameters.

Hardware Limit

Some motors have a hardware speed limit — the motor physically cannot spin faster than a certain RPM, or the controller hardware caps the current at a certain speed. These are harder (sometimes impossible) to bypass without replacing the controller.

What Happens When You Derestrict

Performance Changes

• Higher top speed: typically 32–50 km/h depending on the motor, battery voltage, and rider weight
• Faster acceleration: the motor keeps pushing beyond 25 km/h instead of fading out
• Reduced range: the motor draws more power at higher speeds. Battery consumption increases roughly with the square of speed — doubling speed quadruples energy use. A derestricted bike may lose 30–50 % of its range.
• More heat: the motor runs at higher RPM and current for longer. Overheating risk increases, especially on sustained high-speed rides or climbs.

Handling Changes

These are less obvious but more dangerous:

• Longer stopping distances: bicycle brakes (even hydraulic discs) are designed for bicycle speeds. At 40 km/h on a 25 kg bike, stopping distance increases by 50–80 % compared to 25 km/h.
• Tyre performance: e-bike tyres are rated for e-bike speeds. At 40+ km/h, tyre grip, puncture resistance, and heat build-up change.
• Frame and fork stress: bicycle frames are designed for bicycle forces. Sustained 40+ km/h riding, especially on rough surfaces, subjects the frame to stresses it was not engineered for.
• Suspension: if the bike has suspension, it is tuned for e-bike speeds. Higher speeds mean harder impacts and faster compression — the suspension may bottom out or behave unpredictably.

Legal Consequences in Australia

The Bike Is No Longer a Bicycle

A derestricted e-bike does not meet the legal definition of a bicycle. It is classified as a motor vehicle — the same category as a motorcycle or moped.

This means:

• You need registration (which you cannot get, because the bike does not meet motor vehicle design standards)
• You need compulsory third-party insurance (CTP/TAC)
• You need a motorcycle licence (or at minimum, a moped licence)
• The bike must meet Australian Design Rules (ADR) for motor vehicles — lights, indicators, mirrors, horn, tyres, braking standards

In practice: a derestricted e-bike cannot be registered because it does not meet ADR standards. This makes it illegal to ride on any public road, path, or footpath — not just "not a bicycle," but literally unregisterable.

Fines

If caught riding a derestricted e-bike, you can be fined for:

• Riding an unregistered motor vehicle
• Riding without CTP/TAC insurance
• Riding without an appropriate licence
• Riding a vehicle that does not meet ADR standards

Fines vary by state but can total $1,000–$5,000+ across multiple offences.

Insurance Implications

If you are involved in an accident on a derestricted e-bike:

• Your bicycle insurance is void (the bike is not a bicycle)
• Your home and contents insurance may deny a theft claim (the bike was modified to be non-compliant)
• TAC/CTP coverage does not apply (the bike is unregistered and uninsured)
• You are personally liable for any damage or injury you cause — with no insurance backing

If you injure a pedestrian at 40 km/h on a derestricted e-bike, you face personal liability for their medical costs, lost income, and pain and suffering — potentially hundreds of thousands of dollars.

Warranty

Most manufacturers explicitly void the warranty if the bike is derestricted. The motor controller logs operating data — including maximum speed reached. If you send the bike in for a warranty claim and the logs show 42 km/h, the claim is denied.

The "Private Property" Exception

Derestriction is not inherently illegal — it is illegal to ride a derestricted e-bike on public roads and paths. On private property (your own land, a private track, a closed course), the road rules do not apply. Some riders derestrict for private off-road use and re-restrict for public road riding.

Practicality: this requires a derestriction device that can be easily toggled on and off — which some dongles support.

Why Riders Derestrict

1. The 25 km/h limit feels slow. On a flat road with no headwind, a fit rider on a regular bike can cruise at 28–30 km/h. An e-bike that cuts out at 25 feels like it holds you back.
2. Keeping up with traffic. In 40, 50, and 60 km/h zones, a 25 km/h e-bike is significantly slower than traffic. Some riders feel unsafe being overtaken constantly.
3. They can. The derestriction devices are cheap ($30–$100), easy to install, and widely available online.

Alternatives to Derestriction

Ride a Speed Pedelec (S-Pedelec)

In some countries (Europe, parts of the US), speed pedelecs are a legal category — e-bikes with assist up to 45 km/h, requiring registration, insurance, and a helmet.

In Australia: there is no speed pedelec category. An e-bike with assist above 25 km/h is a motor vehicle, period. This legal gap frustrates riders who want a fast, legal e-bike.

Get Fitter

Above 25 km/h, you are pedalling under your own power. A fitter rider can sustain 30–35 km/h on an e-bike after the motor cuts out. The motor gets you to 25 — your legs take you further.

Choose a More Efficient Bike

A lighter bike with thinner tyres, a more aerodynamic riding position, and efficient gearing will coast faster above 25 km/h after the motor cuts out. The motor limit does not change, but the bike's roll-out above 25 km/h is better.

Bottom Line

Derestricting an e-bike is straightforward, cheap, and tempting. It is also illegal on public roads, voids your warranty, invalidates your insurance, and creates personal liability for any accident you cause. The legal consequences are not theoretical — police in Melbourne, Sydney, and Brisbane actively target modified e-bikes and e-scooters. If you want to go faster than 25 km/h, pedal harder — or advocate for a legal speed pedelec category in Australia.