California lawmakers are once again taking aim at the gray areas of electric bike regulation, this time by targeting what has quietly become one of the biggest loopholes in the state’s e-bike laws.
On Friday, Diane Papan (D–San Mateo) introduced Assembly Bill 1557, a measure designed to clarify that electric bicycles sold and operated in California must be limited to a maximum of 750 watts of peak motor power. If passed, the bill would end the long-running practice of marketing increasingly powerful e-bikes as “750-watt” and therefore street-legal, even when they can briefly deliver far more power than that.
Under current California law, e-bikes are limited to 750W, but the statute does not explicitly define whether that cap applies to continuous power or peak output. Many manufacturers have leaned hard into that ambiguity, advertising bikes as compliant while allowing short bursts of power that translate into rapid acceleration and higher real-world speeds.
The difference between continuous and peak power is that the former is theoretically the maximum amount of power that the motor can sustain indefinitely, while the latter is a fuzzier number that represents the maximum power the motor can provide in short bursts, though neither has a truly standardized method of measurement.
According to Papan, that gap between labeling and reality is contributing to a rise in serious injuries, particularly among younger riders. Trauma surgeons and public health officials have reported that e-bike crash victims are often more severely injured than traditional cyclists, with injury patterns that more closely resemble motorcycle crashes. Marin County, in particular, has seen high-profile youth injuries that helped push the issue into the legislative spotlight.
AB 1557 would draw a very clean line: any electric bicycle capable of producing more than 750 watts of peak power would no longer qualify as an e-bike under California law. That could force manufacturers to rein in motor tuning or reclassify certain models entirely.
As Papan put it, e-bikes remain an important tool for mobility and sustainability, but the state appears increasingly unwilling to let blurred definitions undermine safety.
Electrek’s Take
This is cute, and I get the logic behind it, sort of. But a fundamental lack of understanding of both physics and marketing means that this rule change would be mostly bark and little bite, though it would create a nuisance for e-bike retailers in the US.
First of all, I don’t think higher power motors are the main danger on an e-bike. That’s because unlike nearly every other type of transportation in the US, e-bikes are speed limited (well, legal ones are). So regardless of how powerful the motor is, it still cuts off at 20 mph (32 km/h) for Class 1 and 2 e-bikes. The only difference that power makes is that the bike gets to 20 mph quicker because it has stronger acceleration. Basically, it’s not as sluggish off the line. But crashes aren’t happening because the bike gets to top speed in 6 seconds instead of 9 seconds. They’re happening because parents bought their 14 year old an e-bike and the kid didn’t have the rider training to use it responsibly or understand the rules of the road to ride safely in traffic. So I think the goal of reigning in motor wattage with an eye on safety is misguided.
Next, the whole idea of using motor wattage as a benchmark is silly because these are all made up numbers anyway. In reality, there’s really no such thing as hard and fast power numbers when it comes to e-bike motors. While we often throw around terms like “500W motor” and “750W motors”, these are just approximations. It’s not a figure like mass, where you can weigh a motor and say that it weighs 2.5 kg. Power numbers depend on many other factors, several of which are unrelated to the motor. For example, taking a “750W” motor and connecting it to a 1,000W speed controller (the electrical brain of an e-bike) would cause that 750W motor to operate at around 1,000W of power. The motor may eventually overheat on a long hill or other sustained high-power scenario, but it would do it. So was it really a 750W motor to begin with? Was it a 1,000W motor? Should we have called it a 2,000W motor because the controller could have been 2,000W, if we so chose?
The simple fact of the matter is that the power ratings for motors are just what the manufacturer has labeled them, and are basically nominal figures – i.e., they’re a name. Look no further than the fact that they land at nice, easy round numbers of 250, 500, 750, 1,000W, etc. If these were real, hard and fast measurements, then we’d have a lot of 782W or 239W motors out there.
So California can try to get nitpicky with motor wattage laws all it wants, but since these figures are mostly nominal anyway, it just means e-bike companies will have to be careful with how they name their motors. It will surely sow confusion when the same e-bikes suddenly come with lower power stickers, or a separate “California edition” is rated with lower power despite otherwise looking identical, but that’s where we are.
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