SIOUX FALLS, S.D. (AP) — The 14-year-old was riding an electric bicycle at an estimated 25 mph when he slammed into Janet Stotko during her evening walk, leaving her unconscious and bleeding on a sidewalk in her Minnesota neighborhood.

The 2024 crash nearly killed Stotko, who was raced to a hospital with severe brain injuries, a facial fracture and broken eardrum. But after being on a ventilator for two days, spending three weeks in the hospital and enduring brain surgery, she survived, surprising even her doctors.

At a checkup, she said, her doctors told her, “Wow, we can’t believe you’re here.”

Now, she’s pushing for stricter laws regulating e-bikes in hopes that others won’t be hurt.

E-bikes offer a convenient, eco-friendly and cost-effective alternative to cars, but their increasing use is drawing safety concerns. A study by the University of California, San Francisco found that rider injuries from e-bikes nearly doubled each year from 2017 to 2022, and a University of California, San Diego study showed injuries in San Diego among e-bike riders under 18 soared 300% from 2019 to 2023.

Under federal law, most e-bikes are considered nonmotorized vehicles just like traditional bicycles, so riders don’t need a driver’s license or insurance and they don’t have to wear a helmet. But many states have more stringent rules, and regulations vary widely.

Health experts have called for new laws and better enforcement of existing regulations, and officials in many places are taking action.

Here’s what e-bikers should know to keep themselves and people around them safe.

Not all e-bikes are the same

Many states have adopted a three-tier classification of e-bikes: Class 1 have motors that kick in while riders pedal with maximum speeds of 20 mph; Class 2 have throttles that reach the 20 mph maximum without pedaling; and Class 3 provide pedal-assist up to 28 mph.

There are faster versions available, sometimes called e-motos, that can reach 40 mph even without pedaling. Many states treat these bikes like motorcycles, so they’re not allowed on sidewalks or paths, but in some states there are no specific rules for the ultra-fast bikes.

As John Maa, a general surgeon at MarinHealth Medical Center in Northern California, notes, it’s basic math that increased speeds lead to increased injuries.

“It’s Newton’s principles, right? Force equals mass times acceleration, and also kinetic energy is mass times velocity squared,” Maa said.

Learn where you can and can’t ride

Speed limits, helmet requirements and other rules for e-bikes are changing rapidly, and what’s legal in one city or state might be illegal in the next.

New York City imposed a speed limit of 15 mph on all electric bikes in October, and Florida lawmakers recently sent the governor a bill limiting e-bike speeds to 10 mph within 50 feet of pedestrians. In Connecticut, an October law requires all e-bike riders to wear a helmet, and bikes without pedals equipped with batteries over 750 watts will require a driver’s license.

“We were not only hearing from manufacturers and riders, but we were hearing from concerned citizens trying to share the road with these new electric bikes and e-scooters, and also law enforcement who really needed some clear policies set into place,” said Christine Cohen, the Connecticut state senator behind the legislation.

Know your bike

The market is full of vehicles that blur the line between a traditional e-bike and something closer to a motorcycle, and manufacturers don’t always make the distinction easy to spot.

To understand a bike’s capabilities and where it can be legally ridden, check its top speed, motor wattage, and whether it requires pedaling or operates on throttle alone. Anything outside the three-class classification could be subject to motor vehicle regulations, making it illegal to ride on some shared-use paths where slower e-bikes are allowed.

“The first thing we always tell people is familiarize yourself, read the manual, look at some videos, look at your specific model,” said Charles DiMaggio, an injury public health researcher and professor at New York University’s medical school.

Going to a local bike shop instead of buying online can help, enabling riders to ask questions, take a test ride and learn what’s legal and what isn’t.

Follow traditional bike safety measures

Hospitals and medical groups like the American College of Surgeons and American Association of Neurological Surgeons have called for stricter policies and offered safety tips.

Above all, they stress wearing a helmet. Other tips include riding defensively around cars, using front and rear lights, wearing reflective vests in the dark, and avoiding biking under the influence of drugs or alcohol. Experts also recommend against altering an e-bike to make it faster.

Maa added that e-bike riders should consider wearing a motorcycle helmet that covers the neck to protect against spinal injuries. He also advises parents to make sure their children can comfortably ride a pedal bike before they graduate to e-bikes.

“Make sure they’re comfortable, they understand the rules of the road, they’re able to navigate turns, understand the flow of traffic, the use of bicycle lanes,” Maa said.

Minnesota victim wants accountability

After she was injured, Stotko told the city council in her community of Hastings, Minnesota, about her crash to push for a stricter ordinance. The city agreed, reducing maximum e-bike speeds to 15 mph on city trails, prohibiting e-bikes on sidewalks and imposing penalties.

City police issued a citation to the 14-year-old rider for operating an e-bike underage, but no one was charged for the injury to Stotko.

“It’s really about taking accountability and ownership of owning an e-bike and operating one,” she said.