The warning comes as the popularity of e-bikes continues to grow, along with concerns that some bikes are being altered to exceed legal speed limits and bypass safety requirements.
Under state law, Class 1 e-bikes provide pedal assistance only, while Class 2 e-bikes can operate with a throttle. Both are limited to 20 miles per hour.
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"This gives me a little bit of assistance, a little push but only when I pedal," said ABC7 reporter Lyanne Melendez while demonstrating a Class 1 e-bike. "The fastest I can go is 20 miles an hour." Class 2 e-bikes also cap speeds at 20 miles per hour, but some models can be altered. "Then you have the Class 2 e-bike. I have these pedals but I don't have to use them because I've got a throttle," Melendez said.
"Look mom, no pedals. The maximum speed it allows me to go is also 20 miles an hour. But there's a way to modify that."
Manufacturers set the 20-mile-per-hour limit to comply with federal law, but some bikes can be altered or "unlocked" to go faster.
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"So in some cases there are bikes that are sold as Class 2 bike that then can be 'unlocked' or 'jail broken' so that they go over 20 miles an hour, that's against the rules," said Karen Wiener, owner of The New Wheel electric bike shop.
Wiener said some bikes sold by overseas companies exceed even higher thresholds.
"I welcome enforcement, and I think that most effective enforcement will be at the border that the things that are being imported are proper and legal and safe," she said.
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Once an e-bike exceeds 28 miles per hour, it is no longer legally considered an e-bike. These vehicles, often referred to as "e-motos," are subject to the same requirements as mopeds, including a helmet, a driver's license, a license plate and insurance.
Concerns also extend to how some e-bikes are being used. Melendez observed riders operating bikes without pedals and using sidewalks, which is illegal.
"You have no pedals. What happened to you pedal? What happened to your pedal? Pedal. That one doesn't have it either," she said while recording riders in traffic.
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Peter Chu, owner of HMP Bikes, which rents and sells e-bikes, said his bikes are capped at 20 miles per hour but acknowledged riders may alter them after purchase.
"What they are looking for is to get on the scooter faster, make more money," Chu said. Chu said some bikes are modified by adding higher-voltage batteries. "That's going to be like 30, 31. Oof, crazy dangerous," he said. Chu said responsibility for enforcement should be shared.
"We really want cooperation with certain departments like police department to give a broader education about these things. We don't want anybody to get hurt," he said.
San Francisco District Attorney Brooke Jenkins and other Bay Area prosecutors recently issued a consumer alert reminding manufacturers, retailers, consumers and parents about e-bike laws.
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"We need to be making sure that what is on our roads are safe, not only for the rider but for vehicles and pedestrians who are sharing sidewalks and roads with these e-bikes," Jenkins said.
Wiener said the issue goes beyond classification.
"From my perceptive, what we're dealing with here is an enforcement issue more than a classification issue. We already have the classification, the problem is that the state has very little recourse for people who are moving there bike into the e-moto category," she said.
Safety concerns are underscored by injury data. A University of California, San Francisco study found that rider injuries from e-bikes nearly doubled each year from 2017 to 2022, as sales of the bikes increased.
There is a third classification of e-bikes that doesn't have a throttle and only has pedals with a stronger motor that allows a person to go up to 28 miles an hour. This kind of e-bike cannot be tampered with and is used by serious bicyclists who are commuters who typically have to go a long distance.