Rachelle Kuebler-Weber had only been riding the Jump pedal-assist electric bike for about 15 minutes when the front wheel locked up, sending her flying over the handlebars.

“It happened as soon as I hit the brakes,” Kuebler-Weber said. “I barely touched it. It was like the front tire hit a brick wall.” The fall broke her wrist, gave her a mild concussion, and left her left side completely bruised. She posted several photos of herself looking downcast in a cast and sling on Facebook.

Jump, which is owned by ride-hail giant Uber, has hundreds of pedal-assist electric bikes scattered across dozens of cities in the US and Europe. The red-painted bikes use the same brand of brakes — Japan’s Shimano — as rival Lyft, which operates bike-share systems in cities across the country through its Motivate subsidiary.

Uber acknowledges that it uses the same brake as Lyft

This week, Lyft recalled thousands of e-bikes in New York City, Washington, DC, and San Francisco due to braking problems that caused some of the bikes’ front wheels to lock up. Uber acknowledges that it uses the same brake as Lyft, but it claims it has modified them to address the malfunction. Uber’s explanation was first reported by The Washington Post.

Several riders of Lyft’s bikes have come forward with stories of accidents and injuries, but fewer are reporting issues with Uber’s Jump bikes. That said, at least three Jump customers have posted on social media about their accounts of accidents or near-accidents because of allegedly faulty brakes. The Verge spoke to two of them.

Kuebler-Weber said she owns an e-bike and considers herself a savvy rider. “I have a lot of experience with electric bikes and cycling in general, and have NEVER fallen as an adult,” she wrote on Facebook. “You guys need to tune your systems before putting these new bikes out on the road. Brakes completely locking with barely a touch should never happen.”

“Brakes completely locking with barely a touch should never happen.”

She sent a summary of the accident and photos of her injuries to Jump. The company told her that they would pull the bike from service, investigate what happened, and then follow up. She has yet to hear back.

Matthew Bruckner, a law professor in Washington, DC, told The Verge that he encountered a similar problem while riding one of Jump’s e-bikes to work last August. Bruckner said he heard what sounded like a “small explosion” after squeezing the brakes while riding downhill. The front wheel briefly locked, but he managed to stay upright.

“If the brake would have stayed locked, I would have been gone,” he said. “That would have been it.”

In a one-star review on Yelp, a Sacramento resident named “Amber B.” posted a picture of her severely bruised leg, an injury she says she sustained after riding a Jump e-bike. The story is similar: she applied the brakes, and the bike locked up. “All the sudden the back end of the bike came out from under me and I fell down with the bike landing on top of my leg,” she wrote. The fall left her “really shaken up from the experience and hurt.”

If there are other incidents, Uber won’t say. Matthew Wing, a spokesperson for the company, said in a statement, “Late last year we introduced an updated model bike with a new brake system. Our older bikes have Shimano brakes but with a hardware modification to improve braking.”

Uber plans to completely replace its older bikes with the new models within a few months. The company says it implemented the hardware modification to the brake system in its older model bikes a year ago so the braking response is smoother and more gradual.

“Uber should have notified everybody.”

After its braking issue emerged, Lyft sent a message to riders and published a blog post explaining its decision to recall its e-bike fleet, saying it was making the move “out of an abundance of caution.” A member of the board of the San Francisco Metropolitan Transportation Authority says Uber should afford its riders the same courtesy. “Just like Lyft notified everybody, Uber should have notified everybody,” Cheryl Brinkman, who sits on the SFMTA board of directors, told the San Francisco Examiner.

Kuebler-Weber agreed. “Uber never said a word,” she said. Since her injury, she’s been forced to use Uber’s ride-hail service almost daily to get around. She may have a torn ligament in her wrist. But as for Jump’s e-bikes, “I’ll never touch one again,” she said.

Update April 17th 11:31AM ET: An Uber spokesperson clarified the timing of the brake modification after the publication of this article.