In London, UK last month, Sakine Cihan was hit by an electric bicycle and subsequently died in the hospital. This tragic incident isn’t alone. Electric bicycles have been implicated in deaths in studies from the Netherlands, Israel, and Beijing, although almost all of those fatalities were on the part of cyclists, not pedestrians. Studies in Israel and Switzerland found more injuries, again almost entirely to users of electric bicycles, not others.
Perhaps this is what was on the New York City administration’s mind in October 2017 when it cracked down on electric bikes, especially for delivery services. At the time, it claimed that it had hard data supporting increased danger to pedestrians. However, when pressed later, a city spokesperson made it clear that they didn’t track electric bike incidents separately.
311 does record persistent, “chronic” problems caused by biking, rollerblading or skating, but doesn’t break down those complaints to show how many stemmed from e-bikes, Grybauskas said. About 400 such calls have been made in the past year, with most coming from the Upper West Side, Grybauskas said. But that number includes complaints about all kinds of bicycles, as well as skateboarders and roller-bladers.
A year later, New York has amended its position. Since July 2018, electric bicycles limited to 20 kph have been permitted, specifically those with acceleration solely controlled by pedaling.
So what are the actual dangers of electric bicycles, and to who?
The answer varies somewhat around the world. In the Netherlands, the study shows that it’s mostly older male cyclists who are ending up in the hospital or worse. 31 of 38 fatalities in the study were men over 65. The study’s authors point to several factors which combine to cause issues. The increased speed of the electric bicycles vs pedal bikes in the same age cohort suggests that reduced time to react combined with slower reaction times was a factor. The increased weight of the bikes combined with diminished muscle tone was considered a concern. And that it was men not women who were the very large majority indicated a risk perception difference, likely due to great diminishment of physical capability for men vs women.
In Israel, the study between 2013 and 2015 found 795 injuries, 8% of which were of pedestrians, not riders. Children, women and seniors were relatively equally represented among those injured. Two of the pedestrians who were struck later died of their injuries. The study focused on poor cycling infrastructure, with both a lack of separated bike lanes and pedestrians accidentally walking along in bike lanes as the cause of concerns.
Switzerland has had a long history of electric bicycle adoption, with penetration increasing from 2005 to the present. And with that has come injuries. The study in question tracked electric bicycle related injuries for people admitted to an emergency department in Bern. Once again, more mature men represent the majority of those showing up with injuries, with 70% being male and most being over 40. This study pointed not to decreased physical capabilities, but to another urban cycling challenge common in European cities, tram rails. No pedestrians were reported among those injured.
The Chinese studies found yet another pattern of danger. Most of the injuries on electric bicycles came from a lack of helmets and collisions with cars. The large Beijing study was devoted to car and electric bicycle interactions.
The force of impact of an electric bicycle and rider on a pedestrian can be almost four times harder
There are some commonalities that emerge among the various studies and reports from around the world. The first is that electric bicycles are both heavier and travel faster, making them more dangerous to both their riders and to pedestrians unlucky enough to be hit by them. This can be most clearly understood by looking at the formula for the energy of impacts:
F = (0.5 * m * v^2) ÷ d
Let’s pull that apart a bit. F is force. M is mass. V is velocity. D is distance traveled from time of impact to a complete stop. There are two components that matter for this, mass and velocity. Electric bicycles are typically two to three times the mass of non-electric bicycles, and this extra mass is additive to the body weight of the rider. Taking an example, a 70 kg rider on a 10 kg road bike has a combined mass of 80 kg, while if they are on a 30 kg electric bike the combined mass is 100 kg, 25% higher than alone. Electric bicycles are usually legally limited to 25 kph on city streets, while the average cycling speed in Copenhagen is 15.5 kph. Assuming the potential for 9.5 kph higher impact and 25% higher mass, the force of impact of an electric bicycle and rider on a pedestrian can be almost four times harder.
This potential for much harder impacts on pedestrians has safety experts understandably worried. Let’s take another example, that of an electric bicycle that’s heavier and faster, both of which exist. The Sur Ron MX Electric bike is top of the line, and sold only for off-road use, although it’s easy to find videos of it on city streets. It weighs 50 kg and has a top speed of 80 kph. An impact with a pedestrian given a rider of the same weight would be in the range of 45 times harder.
Pulling at another thread, electric bicycles are causing accidents among men more often than women in Europe. The Netherlands experience is most telling. Electric bicycles are especially dominant among the old, as they no longer have the physical capacity to bicycle themselves due to failing health. However, electric bicycles are also heavier and move faster than the bicycles they used to ride. Once again, physics does not favor this equation. There are a three key points to attend to. First is that in general, human reaction times get worse as we age, although this is both highly variable and somewhat trainable. If two riders see something ahead of them on the road such as a pothole, the older one will react somewhat more slowly by braking or swerving. The second is that with higher velocity on an electric bike, there is less time before you reach the obstacle. That combination alone is a challenge. But the next one is the kicker. As with impacts, braking is a exponentially related to velocity, not linearly. That means that as you travel more quickly, it can take a lot longer to slow down, and that slowing mostly occurs at the end of the braking cycle, i.e. it takes a lot less time to slow from 15 kph to 0 kph, than from 25 kph to 15 kph. The weight of an electric bicycle has one last impact. They are a little less nimble, in general, than lighter non-electric bikes. It takes more muscle and technique to swerve or bunnyhop one, one of which usually diminishes with age.
Cycling infrastructure is important to consider, but it comes with its own problems. Separated bicycle lanes shared by electric bicycles means that there are heavier and faster vehicles co-existing in narrow paths with relatively hard boundaries. Many cycling organizations have fought against electric bikes and electric motor scooters being allowed in bicycle lanes in cities around the world as a result.
Finally, electric bicycles share something with electric cars: they are delightfully quiet. That too comes with an issue. The disparity in weight and speed means that pedestrians have to treat them more as motorized vehicles in terms of treating them with respect, but pedestrians don’t hear them coming.
Urban planners and traffic safety regulators are struggling to come to grips with electric bicycles. They offer tremendous advantages for urban mobility, they reduce congestion, they offload overloaded transit, every electric bicycle is arguably one less car on crowded city streets, and they don’t pollute. But the interaction between electric bicycles, pedestrians, cars, trucks, and other cyclists needs attention, especially as electric bicycles continue to take market share from small motorcycles and bicycles.