Experts on Camera

Dr. Jennifer Dill: Electric bikes

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“E-bikes” are soaring in popularity, and many cities and states are offering rebates, tax credits, or other incentives to purchase them.

On Thursday, May 11, 2023, SciLine interviewed: Dr. Jennifer Dill, a professor of urban studies and planning and director of the Transportation Research and Education Center (TREC) at Portland State University. She discussed topics including: E-bike purchasing and ridership trends; the effects of programs incentivizing the purchase of e-bikes; the health and mobility benefits of e-bikes; environmental sustainability of e-bikes compared to gas- or electric-powered cars; how e-bikes fit into the transportation landscape in urban, suburban, and rural areas; and e-bikes effects on road safety, for both e-bike riders and other users of the road including bicyclists, pedestrians, and motorists.

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JENNIFER DILL: My name is Jennifer Dill. I’m a professor at Portland State University, where I also direct our Transportation Research and Education Center. My research focuses on active transportation, mainly bicycling and walking. And I look at questions of why people decide to use those modes and the effects on their health and other factors.


Interview with SciLine

What is an electric bicycle, or e-bike?


JENNIFER DILL: It’s really important when we talk about e-bikes to understand what we mean when we use the term e-bike, particularly in the U.S. Most states in the U.S. have adopted a three-tiered classification system for e-bikes. Two of those types of e-bikes are what we call pedal, or electric assist. In other words, you have to be pedaling the bike to make it go. It will not go on its own. And those two types, one of them limits the top speed with assist to 20 miles an hour, and the other up to 28 miles an hour—or otherwise, the motor will cut off. A third type of e-bike is what we call a throttle e-bike, where it will actually go without you pedaling. And that also maxes out at 20 miles an hour with that electric assist. The other thing that’s really important to know in the U.S., at least: All e-bikes—official e-bikes—do have to have pedals that work. So, you have to be able to ride the bike like a standard bike without electric assist. And that may be in contrast—and as some people visit other countries and see different types of e-bikes that are really more, in the U.S., what we would call a moped or even an electric motorcycle.

Can you describe any current trends in e-bike purchasing and ridership?


JENNIFER DILL: I would say overall across the world—and in the U.S.—e-bikes are booming, becoming much more popular and a bit more mainstream. So, between 2018 and 2021, the number of e-bikes sold annually in the U.S. went from 300,000 to over a million. And there’s one estimate that in 2021 there were more e-bikes sold in U.S. than electric cars and trucks. But we do have to keep in mind that, similar to cars, e-bikes are still a very small fraction of all of the bicycles out there in the U.S.

What city programs exist to incentivize the use of e-bikes, and what effects do those programs have?


JENNIFER DILL: At Portland State University, we’re keeping an inventory of all programs across the U.S. and Canada that are offering incentives to the public, including things like rebates, free bikes, e-bike lending programs, tax waivers, other types of incentives. At last count, we found at least 70 active pilot or adopted programs that are about to be implemented in the U.S. with another 33 proposed. So, the numbers have been increasing. And those incentives are particularly important for low-income households because e-bikes are not cheap, at least a high-quality one. The price of a typical e-bike ranges from about $1,000 to over $5,000, averaging maybe around $2,500 or so. And we have found that, of the incentive programs that are out there in the U.S., over a quarter them do give priority to lower-income households in terms of purchases or loans. There’s another type of incentive program aside from the rebates. There are also programs that loan e-bikes out to people to test them out because it is a new technology that people are generally unfamiliar with. And particularly if you haven’t even ridden a bike in a long time, trying one out can be pretty effective at making a decision on whether or not it’s going to work for you. We’ve done some research in the Portland area with a large hospital system, where the program lent e-bikes to employees for a six-week period to test them out. And some of these were pretty suburban locations. And we found that the share of those employees who were biking to work nearly doubled to almost 60%. There’s other evidence from employer-based programs that these types of loan programs can encourage people to purchase their own bike afterwards.

What are the benefits of e-bikes for health and well-being?


JENNIFER DILL: I think there’s a myth out there—or a bias among some people that think that e-bikes are maybe cheating, and you don’t get exercise. But there’s ample peer-reviewed evidence that e-bikes actually do contribute to health and do provide adequate physical activity. In particular, we know that when you’re riding an e-bike, it is lower intensity when you’re using that electric assist. But the research has found that people still are in that range of moderate-to-vigorous physical activity, which is what the health recommendations are for adults. We also find that while it may be lower intensity while you’re riding the e-bike, e-bike riders ride more often and often for longer distances, so they’re still getting great health benefits. Another really important thing that we have found about e-bikes is that they work for people who can’t ride a standard bicycle. So, in our national survey, we found that 29% of e-bike owners said they had some sort of physical limitation that made riding a standard bicycle difficult. And 10% of them said they couldn’t even physically ride a standard bicycle. So, it’s really providing health benefits, particularly for people who don’t have another option in terms of a bicycle. The other thing—there’s a lot of research out there that shows that the transportation mode that you use can affect your wellness and your mental health. And numerous studies, including some that we’ve done, have found that people who are riding bikes, particularly for commuting, have greater well-being in terms of their commute and are happier about their commute. And that can correlate with overall better well-being. And e-bikes, in particular—we have found that people just enjoy them. They say they are fun, and that can have positive effects on your overall well being.

What about benefits for the environment?


JENNIFER DILL: One of the reasons we’re seeing these incentive programs being adopted by a lot of public agencies is that there is good evidence that e-bikes have the potential to reduce our use of private automobiles and other vehicles that pollute more. And what we have found through our research is that about a third of the trips that e-bike owners are making were for commuting, and another 20% were for errands. And so, those are what we often call utilitarian type trips. And about two-thirds of those e-bike owners said that they would have driven a car for that trip if they hadn’t used their e-bike. So, we are seeing that e-bike users are using their e-bike instead of driving a car much of the time. And we’ve used those numbers to estimate that for any individual e-bike that is owned, we would reduce carbon emissions by about 225 kilograms per year because of those trade offs.

How do e-bikes affect traffic congestion?


JENNIFER DILL: Well, in general, anytime you get someone out of a car and onto a bike or transit or any other mode, at least initially you will reduce motor vehicle traffic. But we do find that there is a response to that. So, if traffic congestion goes down, there will be other shifts. People will start to see that and start driving other—maybe not the e-bike riders—but other people might shift either the time or their route. So we generally find that when you reduce congestion, unless you do something else like price—put in tolls and things like that—that congestion probably will come back. But what that does mean is we don’t necessarily need to expand our roads, right? So that’s a better way—if we can get more people on e-bikes and other modes of transportation, it’s a way that we can accommodate growth in our cities without necessarily expanding road capacity.

What is known about e-bikes’ effects on road safety?


JENNIFER DILL: Right now, we do not have a lot of good data on e-bike crashes. And that’s because our current systems of reporting crashes don’t distinguish between a standard bike and an e-bike. So, we don’t have great data to really answer a lot of safety questions. What we do know from basic physics is that the faster someone is going on a bike, if they crash, the odds of an injury are going to go up. And that’s similar to cars. The faster car is going, the greater chance of an injury if there’s a crash. We see some evidence from a couple studies that motorists may misjudge how fast an e-bike is going. And so that could contribute to crashes. So far, there’s no strong evidence in the U.S. that e-bike riders exhibit riskier behavior, which is something we’ve seen in other countries. So we’re going to need to continue monitoring and doing research on that.

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[Posted May 11, 2023 | Download video]