I'm thinking of getting an electric bike, and like most, it states the speed limit at 25Kph, which also happens to be the speed I typically cycle at. My question: is this speed set in stone? Is there a limiter of some kind preventing me from going faster? If there is, is this limit defeatable?

  • In the USA, many (but not all) states adopted guidelines from the CPSC -- the Consumer Products Safety Commission -- to inform their own laws. Exactly which laws apply to you, and how each manufacturer interprets them for enforcement reasons, will vary. Nov 19, 2016 at 17:28
  • BTW, different companies read the CSPC's guidelines differently. Optibike, for instance, doesn't implement a cutout, but just has their mid-drive motor sized to a level that complies with the letter of the guidance (not going above 20mph/hr on flat ground with a 180lb rider not pedaling) -- but if you're pedaling along with it, you get the same amount of assistance that you would at a lower speed, and if keeping up a good cadence can often get the motor into more efficient power band than it would be without any input from the rider. Nov 19, 2016 at 17:37
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    Common sense should stop you going too fast. I had an ebike kit on an older MTB, that was capable of 25 km/h, and could do 45 km/h while pedalling madly. Downside is cars could not anticipate my speed and routinely pulled out in front. And the bike's brakes are still only bike brakes. After too many close calls I sold it on and now ride road bikes.
    – Criggie
    Nov 19, 2016 at 20:07
  • Yeah, my vague recollection is that most US states have a horsepower limit and a speed limit -- if the bike exceeds the limits it must be licensed as a motorcycle. The horsepower limit is likely fairly firm (and I think is fairly consistent across the US), but the speed limit is "squishy" since it depends on how hard you pedal. If you somehow defeat the horsepower limit you're breaking the law. Nov 19, 2016 at 20:13
  • nod. Texas, incidentally, also has a weight limit. Makes it tricky for velomobiles and trikes if one's trying to optimize for battery life, comfort and distance rather than weight. Nov 20, 2016 at 1:33

4 Answers 4


The limit is set by law depending on the country. There's nothing to prevent you from going faster if you can pedal harder. The limiter just cuts off the electric assistance above 25km/h, so you'll have to rely on pedal power alone above that speed!

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    To the second part of the question: Defeating the assist limiter is likely illegal, and how its done is likely model specific.
    – Batman
    Nov 19, 2016 at 16:17
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    @Batman, well -- not necessarily illegal in and of itself, but it would make your e-bike no longer a street-legal unlicensed vehicle in many states; if you turn into a moped then you need more safety gear, licensing, &c. If you were using it off-road, then that wouldn't matter for legal reasons -- indeed, there are some companies that sell e-bikes that are outside the US legal limits into the united states specifically for offroad use; the Stealth Bomber comes to mind. Nov 19, 2016 at 17:30
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    @Charles - In many countries, where E Bikes are allowed off road, many trails are restricted to road legal E Bikes.
    – mattnz
    Nov 19, 2016 at 19:23
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    It's worth pointing out that just because your bike is throttled down to a certain limit doesn't mean that's the limit where you are. There are bikes sold in the US for example that are limited to the lowest e-bike limit anywhere in the country, even though the actual limit varies place to place. Nov 19, 2016 at 21:56

If you typically ride at 25km/h there may still be benefits to a compliant electric bike: being less tired, acceleration, and hill climbs. However many electric bikes aren't built to be a fast ride - they're often heavy and have a frame geometry aimed at comfort rather than efficiency. So you may have to pay more than you'd like for a limited benefit. The other option is a retrofit kit (usually the front wheel). There are some ridiculously powerful ones on the market which are legal to sell but not to use on public land (the rules apply to the bike not components), but sensible kits also exist.

  • Care to share some links for these retrofit kits you mention? Nov 21, 2016 at 20:27
  • It's a while since I've looked. I wouldn't want to recommend something that could turn out to be illegal. To get an idea of pricing before looking in more detail you can look on Amazon
    – Chris H
    Nov 21, 2016 at 22:37

You can buy kits to mod the regulator between the battery and the motor. This allows you to modify the acceleration curve of the bike. Kind of like re-jetting a carburetor.

This curve sets the maximum acceleration at a given velocity, which can get you into and out of tight spots faster. Electric motors are capable of instant maximum torque, which just spins the wheels if not regulated (cool, but impractical).

As long as you do not modify the maximum velocity, then it is still legal. Obviously does not change the power rating of the battery or motor. Violates the warranty, though ;)

  • The regulator is exactly the component that regulates the power output, which in turns sets the acceleration curve. There are no laws about that curve, or how fast you are allowed to arrive at maximum power output, whose value is of secondary importance to maximum velocity. Nov 20, 2016 at 1:46
  • Ahh. Yeah, I wasn't reading your answer closely above. Objection withdrawn. Nov 20, 2016 at 1:50

I live in the State of New Hampshire, U.S.A. I can tell you that there is a federal law (http://www.iloveebikes.com/distributorfiles/fedregulation.pdf) that basically defines an electric bicycle as something that goes less that 20m.p.h. You can make them go faster through tinkering, but if it goes faster than that it's considered a Moped, and must be registered to drive on (or beside) any roads. If it looks like a bicycle chances are you won't get caught, unless your going insanely fast (like 30 or 40 MPH or more) but if you do you could very well get ticketed.

  • I'd add that your odds of getting ticketed while riding around are basically zero. But if, god forbid, you cause an accident, you will be punished for using an unregistered vehicle. Aug 2, 2021 at 6:42

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