California’s official collision records now tell a striking story about e-bikes. According to a new UC San Diego study, reported e-bike collisions in the state grew from 2 in 2018 to 1,506 in 2024. The researchers describe the growth as exponential, and the injured e-bike riders skew younger than the state’s injured traditional cyclists.
That headline number is real, and it deserves attention from anyone who rides an e-bike or is about to buy one for a teenager. But it also needs careful handling, because a count of reported collisions is not the same thing as the risk of any individual ride. This article walks through what the study actually found, where its limits are, and what the findings mean in practice for parents and buyers.
What the Researchers Actually Measured
The team analyzed collision data from the California Highway Patrol’s Statewide Integrated Traffic Records System, covering 2018 through 2024. That dataset included 4,035 e-bike collisions alongside 58,332 traditional bicycle collisions, which gives the study an unusually large comparison group.
A few findings stand out from the UC San Diego report:
- Reported e-bike collisions rose from 2 in 2018 to 1,506 in 2024.
- 15.6 percent of injured e-bike riders were age 14 or younger, versus 10.2 percent of injured traditional bicycle riders.
- Moderate-to-severe injuries were more common among e-bike riders than among traditional bicycle riders.
- Overall mortality rates were similar between the two groups across the study period, but the researchers observed a significant increase in e-bike-related deaths in 2024.
- E-bike riders were more likely to be involved in violations involving unsafe speeds and improper turns.
- E-bike collisions were more likely to occur in more affluent communities than traditional bicycle collisions.
In the UC San Diego article, first author John Austin, MD, offered an explanation for the severity gap, describing crash forces in some e-bike collisions as closer to what trauma teams see in motorcycle crashes. That framing comes from the news release as the researchers’ explanation, not as a directly measured finding, so treat it as informed context rather than a lab result.
Study snapshot (figures per UC San Diego Today, July 2026)
data| Metric | E-bike riders | Traditional bicycle riders |
|---|---|---|
| Reported collisions, 2018 through 2024 | 4,035 | 58,332 |
| Annual reported collisions | 2 in 2018, rising to 1,506 in 2024 | Not broken out in the news source |
| Injured riders age 14 or younger | 15.6% | 10.2% |
| Moderate-to-severe injuries | More common | Less common |
| Mortality over the study period | Similar overall, with a significant rise in e-bike deaths in 2024 | Similar overall |
| Common cited violations | Unsafe speeds, improper turns | Not the elevated categories |
Raw Counts Are Not Per-Trip Risk
Here is the distinction that matters most when reading this study, and the one most likely to get lost in scary headlines: the researchers counted reported collisions, not risk per ride.
Going from 2 reported collisions to 1,506 sounds like a 750-fold explosion in danger. The data cannot show that. The study reports collision counts without an exposure denominator, meaning there is no matching data on how many e-bike trips, riders, or miles those crashes came out of. Without that denominator, a rising count is compatible with rising risk, with flat risk spread over far more riding, or with some mix of the two.
Two plausible factors deserve mention here, and both have to be framed carefully. E-bike adoption in California may have grown substantially over these years, which by itself would push crash counts up even if each ride carried the same risk. Reporting and classification practices may also have shifted, since how officers categorize an e-bike crash could have changed as the vehicle category became more familiar. Both are plausible contributors to the growth curve. Neither is measured in this dataset, and the study design cannot separate either one from a genuine change in risk. Treating any of these explanations as established would repeat the same mistake as treating the raw count as proof of danger.
So the honest reading is narrower but still important. California’s statewide traffic collision records now contain far more injured e-bike riders than they did six years ago, the injured population includes a disproportionate share of children, and the recorded injuries trend more severe than in traditional bicycle crashes. Those are facts about what the CHP records contain. What no one can say from this data is that your individual ride got exponentially more dangerous, and the study, read carefully, does not claim that.
It is also worth resisting the opposite temptation. “It is just more riders” does not dissolve every finding. The severity comparison is drawn among recorded injured riders, e-bike against traditional bicycle, and it remains an important observed association even with the exposure question open. It is still an observational result, so it does not establish that e-bikes cause worse injuries, and differences in who ends up in the records could shape it. But more kids under 15 among the injured and more moderate-to-severe recorded outcomes are signals worth acting on while better data develops.
Why the Youth Numbers Deserve the Most Attention
The share of injured riders age 14 or younger, 15.6 percent for e-bikes against 10.2 percent for traditional bikes, lands in a specific policy moment. San Diego County has already moved on youth e-bike restrictions, which we covered in our report on San Diego’s e-bike age rules, and other jurisdictions from Colorado to Watertown, New York have been redrawing the lines around who can ride what, where, and with what gear.
The violation data adds context. E-bike riders in the dataset were more likely to be involved in violations for unsafe speeds and improper turns. The study does not report why, and the records do not tie those violations to rider age, so the careful reading is simply that speed-related and turning mistakes appear more often in the e-bike crash reports. That is still useful information for anyone deciding how much speed to put under a new rider.
The affluence finding is harder to interpret. E-bike collisions clustered in wealthier communities compared with traditional bicycle crashes. The study reports the pattern without explaining it, and the dataset contains no information about who owns which bikes or why crashes concentrate where they do. It stands as an observation about where recorded e-bike crashes happen, not a story about any particular kind of household.
The researchers’ own recommendations are measured: rider education, consistent helmet use, safer infrastructure, and policy tailored to how e-bikes actually differ from bicycles. They also plan to link collision records with hospital and trauma data in future work, which should sharpen the severity picture considerably.
What Parents and Buyers Should Do With This
None of this argues against buying an e-bike. It argues for buying deliberately, especially when the rider is young. A practical checklist, consistent with what the researchers found and recommended:
- Confirm the legal class before anything else. Class 1, 2, and 3 e-bikes have different speed and access rules, and many jurisdictions set age minimums for Class 3, so check local rules before assuming a young teen can ride one. Our guide to e-bike classes explains the differences, and our state-by-state law roundup covers what applies where you live.
- Match power and speed to rider maturity, not to the spec sheet. The violation data centers on unsafe speed. A slower Class 1 bike a young rider can handle beats a faster bike they cannot.
- Budget for a properly fitted, certified bicycle helmet. Consistent helmet use is one of the researchers’ core recommendations, and it only works if the helmet actually fits and actually gets worn.
- Keep the equipment sized and maintained. A correctly sized bike keeps the brakes and controls where a young rider can actually reach and use them, and well-maintained brakes and working lights are baseline requirements on any bike that carries motor speed. This study does not test equipment, so treat this as standard maintenance sense rather than a research finding.
- Practice before traffic. Supervised sessions in an empty lot, covering braking distances, low-speed control, and turning, address the improper-turn and speed mistakes the data highlights.
- Do not confuse an e-moto with a legal e-bike. Off-road electric motorcycles sold without pedals or above class speed limits generally fall outside the e-bike class system, and many places do not allow them on public roads at all. Check local rules before any street riding, and treat these machines as a separate category from the e-bikes this study covers.
The Bottom Line
The UC San Diego study is best read as a warning signal in California’s official collision records, not a per-ride risk verdict. The CHP’s statewide database now records far more injured e-bike riders than in 2018, those riders skew younger than injured cyclists, their recorded injuries trend more severe, and deaths ticked up significantly in 2024. Whether the average ride got riskier is a question this data cannot answer, because nobody counted the rides.
For riders and parents, the useful response is the boring one: right class, right speed for the rider, fitted helmet, working brakes, practice, and a clear line between e-bikes and e-motos. The researchers’ next step, linking crash records to hospital data, should tell us much more about severity. We will cover that work when it publishes.
FAQ
FAQ
+Does the study prove e-bikes became more dangerous per ride?
+What did the study find about children on e-bikes?
+Were e-bike injuries more severe than bicycle injuries?
+Do these numbers apply outside California?
+What should I check before buying an e-bike for a teenager?
Sources
- UC San Diego Study Finds An Exponential Increase in E-Bike Injuries in California (UC San Diego Today, July 20, 2026, by Lizelda Lopez): the primary source for all collision counts, percentages, severity findings, and researcher recommendations in this article. RoostMode did not conduct or participate in this research.
- An Exponential Increase in e-bike Injuries in California (Austin et al., Trauma Surgery and Acute Care Open, July 17, 2026): the peer-reviewed study behind the news article. The UC San Diego source states the authors declared no competing interests.