Electric bikes typically reach speeds between 15-20 mph. Can an electric bike achieve speeds of 40 mph? This represents more than twice the standard speed. Let's dive into whether electric bikes can hit 40 mph and what affects their top speeds.
What Decides How Fast Your E-Bike Can Go
Motor power is the biggest speed factor. Most regular e-bikes come with motors between 250W and 750W, which typically max out at 20-28 mph. To reach 40 mph, you'd need something beefier—around 1,000W or more. Think of it like this: a 250W motor is like a compact car, while a 1,000W+ motor is more like a sports car.
Battery voltage directly impacts your speed potential. Standard e-bikes run on 36V or 48V batteries, but faster models might use 52V or even 72V systems. Higher voltage means more power delivery to the motor, which equals faster speeds. It's like having a bigger fuel line to your engine.
The controller manages how much power flows from the battery to the motor. Some controllers are programmed with speed limits (especially on store-bought e-bikes), while others allow much higher performance. Tweaking these settings can unlock hidden speed, but manufacturers often lock them down for safety and legal reasons.
Weight makes a huge difference. A lighter rider on a lighter bike will go faster with the same motor than a heavier setup. For every 10 pounds you can shed (from either yourself or the bike), you might gain 1-2 mph in top speed.
Aerodynamics matter more than you might think. Once you get above 20 mph, wind resistance becomes your biggest enemy. Crouching down in a more streamlined position can easily add 3-5 mph to your top speed without any mechanical changes.
Tire type and pressure affect how efficiently your electric bike rolls. Skinny, smooth tires pumped to their maximum PSI will roll much faster than knobby, wide, or under-inflated tires. The difference can be 2-4 mph in top speed.
SEE ALSO How Increasing Voltage Impacts Electric Bike Speed and Power
What the Law Says About Fast E-Bikes
In the US, e-bikes come in three main flavors:
Class 1 gives you pedal help up to 20 mph—no throttle, just assistance when you pedal.
Class 2 has a throttle but still maxes out at 20 mph.
Class 3 helps you pedal up to 28 mph, which is quite zippy for bike lanes and paths.
Anything faster than these limits? Well, that's not technically an "e-bike" anymore according to the law. Once you cross that line, your ride becomes a moped or motorcycle in the eyes of the law, bringing a whole new set of rules: registration, insurance, and proper licensing.
Options If You Want to Go 40 mph on Electric Power
If you've got the need for speed, you have some options:
High performance e-bikes push the boundaries of the classification system. Some manufacturers make powerful models that can hit 30-35 mph, though they often ship with limiters to keep them street-legal. These still fall short of 40 mph unless modified.
Electric mopeds and motorcycles are purpose-built for higher speeds. With more powerful motors (often 2,000W+) and frames designed for stability at speed, these can easily hit 40 mph or more. The trade-off? You'll need to register, insure, and license them like any other motorized vehicle.
DIY and modified e-bikes can certainly reach 40 mph with the right upgrades. Some riders swap in bigger motors, higher-voltage batteries, and performance controllers. Just remember—once modified, these usually don't qualify as e-bikes anymore under the law.
The Downsides of Super Fast E-Bikes
Before you set your heart on a 40 mph electric bike, consider these practical issues:
Safety becomes a big deal at these speeds. Bicycle helmets aren't rated for motorcycle-speed crashes. Regular bike brakes might not stop you quickly enough. And hitting a pothole at 40 mph could send you flying. There's a reason motorcycles have beefier frames, suspension, and brakes.
Your battery won't last long at top speeds. Wind resistance increases exponentially with speed. While you might get 40-50 miles of range at 15 mph, that could drop to just 10-15 miles when cruising at 40 mph. That awesome long-range ride you planned? It might end with you pedaling a very heavy bike home without power.
Components wear out faster when pushed to their limits. Chains snap, spokes break, and motors can overheat when regularly running at maximum output. These repairs add up quickly.
You'll draw unwanted attention. Zooming past other cyclists at double their speed or keeping up with cars in the road tends to get noticed—sometimes by law enforcement.
Conclusion
While 40 mph e-bikes exist in the technical sense, they occupy a gray area between bicycles and motorcycles. For most riders, the speed limits on legal e-bikes (like Qiolor JR city bike) provide plenty of zip while keeping things safe and simple. If higher speeds are truly necessary for your commute or riding style, consider vehicles specifically designed for those speeds rather than pushing an e-bike beyond its intended use.
FAQs
Can I remove the speed limiter on my e-bike to go faster?
Technically yes, but doing so typically makes your e-bike illegal for use on public roads and bike paths, voids warranties, and may create safety issues with components not designed for higher speeds.
How much would it cost to build a 40 mph electric bike?
Expect to spend $2,000-5,000 for components that can reliably and safely handle those speeds, plus potentially more for registration and insurance since it would likely be classified as a moped or motorcycle.
Will I get pulled over if my e-bike goes too fast?
It's definitely possible, especially if you're riding at motorcycle speeds without proper registration or in areas restricted to standard bicycles and legal e-bikes. Enforcement varies by location but is becoming more common as e-bikes grow in popularity.
