Nothing compares to the simple pleasure of riding a bike.
— JOHN F. KENNEDY
A simple but significant step forward on my path of self-transformation and transcendence of fossil fuels has been to ride a bike. Biking is a wonderful catalyst for mindset change. It’s so good, in fact, that today I ride not to be low-energy, but because I love to ride.
During my first year in California, I didn’t bike; the idea didn’t occur to me. There was still dissonance between my intellectual understanding of global warming and the way I lived day to day. Instead, I rode a large, 35-miles-per-gallon motorcycle the six miles to and from Caltech.
As I became more aware of the interconnectedness of the components of our predicament and my daily actions, burning gasoline increasingly began to feel wrong. Eventually it occurred to me to bike. I owned a solid bicycle—a sturdy old touring machine that had once carried me across 1,000 miles of erstwhile prairie—but it was sitting, neglected, in the back of my parents’ garage in suburban Chicago. During a visit one Christmas,1 I asked the local bike shop for a box and shipped it west.
What a revelation! The first time I biked to Caltech, the feat seemed epic. Somehow a bike made traveling six miles through the suburbs into a grand adventure. I felt unsteady and awkward at first, but after a few days, biking began to feel good—as if I were flying—a feeling I’d taken for granted as a kid. As my body grew stronger and I gained confidence, I cut my commute time in half. The neighborhoods along my route became familiar. I came to rely on biking as my primary exercise.
I started doing as many errands as possible on my bike. I began bike-towing my kindergarten-aged kids to and from school. I carted groceries home in their bike trailer. My bicycle trip radius expanded, and I learned to use public transit to expand it even more. I came to see Altadena and Los Angeles through new eyes. Today, I still enjoy urban exploration by bike, which has a unique magic.2
Yes, cars are faster over long distances and keep out bad weather. But bikes are better than cars in just about every other way:
• Biking is more fun.
• Biking keeps me fit.
• Biking across town is often faster than driving.
• Biking cures my blues.
• There are no traffic jams on a bike.
• Bike commutes, unlike car commutes, don’t leave me frazzled—and won’t lead to divorce.3
• Biking prevents sickness, at least for me.4
• Biking saves serious money.5
• Bikes are far easier and cheaper to maintain than cars.6
• A good bike can last a lifetime; most cars are junk after eight years.7
• Car ownership is a web of obligations and expenses; biking is simplicity and freedom.
• Biking supports local businesses.8
• Bikes are easy to park—right next to your destination.
• Biking is the antidote to urban sprawl, and over time will lead to more beautiful neighborhoods.
• Biking is quiet.
• Biking leaves the air clean and doesn’t cause respiratory disease.
• Biking is safer for you and for others (more on this below).
• Biking is sexy.
• Biking is adventurous.
• Biking is great thinking time.
• Biking reminds me to enjoy the ride.
Our bodies are made to move!
Let’s carefully address the question of whether biking is more dangerous than driving. Biking does carry risk, and should be undertaken with care, but research unequivocally shows that riding a bike is safer than driving a car. This truth probably comes as a surprise. It surprised me, at least.
As you’d expect, the risk of injury on a bike is higher. But people who bike regularly are so much less likely to die from heart disease (heart attacks and strokes) that on balance biking is safer. When all causes of death are taken into account, and when averaged over a large enough population, it turns out that bicycling is roughly ten times safer than driving (not bicycling) because the health benefits outweigh the risks.
De Hartog et al. estimated that the physical exercise due to bicycling 4.7–9.3 miles (7.5–15 km) per day9 adds between 90 and 420 days of life expectancy, whereas the risk of accidents subtracts between 5 and 9 days and the risk of increased inhaled air pollution from motor traffic subtracts between 0.8 and 40 days.10
Overall, their best estimate is that the benefits of a modest (three miles each way) bicycle commute outweigh the risks by a factor of nine.11 Biking is also less likely to kill others, but that’s a separate effect.
This result is corroborated by several other studies. To give one example, Rojas-Rueda et al., who studied Barcelona’s bike sharing program, estimate the biking benefit (in all-cause mortality) to be well over a factor of ten.12 On the other hand, I couldn’t find a single peer-reviewed study concluding that driving was safer than biking.
In my opinion, this is revolutionary information. Because of it, I now think about biking and driving in a completely new way. The studies also demonstrate the dangerous human tendency to ignore risks from gradual processes such as heart disease (or global warming), and to give too much weight to risks with lower likelihood but higher immediacy.
Finally, it’s possible to tip these already great odds dramatically further in your favor by biking smart: ride sober,13 follow the rules of the road,14 avoid dangerous situations,15 wear a helmet,16 and use lights at night.17
Once, when I still flew on commercial airplanes, I took a trip to Hannover, Germany, to meet with astrophysics colleagues. What struck me most immediately about Hannover—especially coming from Los Angeles—was its bicycle traffic.
Hannover has an extensive system of segregated bike tracks along city streets. Bicycles are accommodated in the street system as equals to cars and pedestrians, not as an afterthought. The countryside around Hannover has a network of bike paths18 running along rivers and lakes connecting the small surrounding towns.
And people in Hannover make great use of their bike infrastructure. Students, business people, mothers with kids, elderly folks are all out rolling along together on the segregated tracks. A friend lent me his mom’s old bike, so I rode everywhere, including to the gravitational-wave detector in nearby Sarstedt.
In Los Angeles, by contrast, bikes have barely registered in the urban planning consciousness. Bike infrastructure here typically consists of signs suggesting that motorists “share the road,” and there are few bicycles on the roads. In the Pasadena urban core, I can ride for miles and I might see two other bicyclists. One Sunday in 2014, during a seven-mile ride from Eagle Rock back to Altadena, I counted the car and bike traffic. I tallied more than 800 cars19 but only one other bike.
In the US, 0.6% of commutes are on bikes20 versus 25% in the Netherlands.21 So the average Netherlander gets on a bike about 40 times more often than the average American. In Amsterdam between 2005 and 2007, residents got onto bikes more often than they got into cars.22 What accounts for this stark difference between the US and Europe? As a biker who thinks about these kinds of things while happily biking along, I’ll suggest three interconnected reasons.
The first is mindset. As the nation was settled, space was something to be conquered; land was something to be “improved.” This historically adversarial sense of space, along with the emergence of a cultural fetishization of convenience (convenience as progress) in the mid-20th century, intensified a national love affair with cars. Americans equate cars with speed, status, power, and freedom. If we think of bikes at all, we think of them more as recreational toys than as serious transportation. We’ve lost the ability to imagine a world not dominated by cars.
The second reason is urban sprawl, the physical imprint of this mindset. Cities and suburbs in the US tend to be more spread out than in Europe, with vast parking lots for cars and poor integration between residential and business districts. European cities were built before cars existed; their compactness makes them bike-friendly. In Europe, there’s simply less distance between where you are and where you need to go.
The third reason is a lack of bike-friendly infrastructure in the US, an unsurprising side effect of the car’s cultural dominance.23 Unlike bikers in Europe, bikers in the US must deal with mega-intersections, hostile and distracted motor traffic, and too-narrow roadways with traffic whizzing by, all while managing the risk of being doored by someone getting out of a parked car. Because of this lack of infrastructure, biking here is thought of as too dangerous. In Europe, segregated bike tracks that connect residential neighborhoods to shops, schools, and places of work increase both actual and perceived safety, making biking viable for even timid or elderly riders.
There’s evidence that if bike infrastructure improves, more people ride, which leads to still more bike infrastructure and still more riders. This in turn changes the culture and makes biking seem normal and less dangerous, which causes even more people to ride.
There’s also a safety in numbers effect: when there are more bikes out, motorists are more aware of bikes. Every doubling of the number of bikers in a community reduces risk of injury from motorists by over 30%.24 This increases the real safety of biking. It also increases the perceived safety of biking. Biking encourages more biking. In the long run, a culture of biking could even reverse urban sprawl, because bicyclists tend to advocate for policies that encourage local businesses and compact, integrated neighborhoods.
Of course, another major advantage of bikes is that they emit less CO2 than cars. However, despite what you may think, biking isn’t necessarily emissions-free.
Let’s compare a mile of driving to a mile of biking. A typical car gets 25 miles per gallon, and burning this gasoline emits 0.5 kg CO2 over a mile.25 It also took fossil fuels to manufacture the car; the climate impact embodied in a typical car is between 9 and 20 tonnes CO2e.26 Cars typically last 150,000 miles, so embodied emissions add an additional 0.1 kg CO2e. A typical driven mile therefore emits a total of 0.6 kg CO2e.
Now consider a typical biker. Riding a bike burns about 50 kilo-calories per mile above the resting rate.27 Producing the food for a typical vegetarian28 for one year creates 1.5 tonnes CO2e (see Chapter 9) which comes out to 0.1 kg CO2e per 50 kilocalories—one vegetarian bicycle mile. A typical meat-eater doubles this, and a proficient organic gardener or freegan could perhaps zero this out. The embodied emissions of the bicycle come out to an insignificant 0.004 kg CO2 per mile.29
On a per-mile basis, then, a 25 mpg car emits six times as much as a vegetarian on a bike. This is a fair comparison for long cross-country trips. But most of our trips are short, in-town trips; and when on a bike, I’m more likely to combine such trips and to choose nearby options like local mom-and-pop businesses. For these trips, I tend to drive about four times as far as I bike to accomplish equivalent tasks. On this basis, the car emits 20 times as much as a vegetarian on a bike, 10 times as much as a meat-eater on a bike, or 500 times as much as a freegan30 on a bike.
While biking has less impact than driving, it still has impact. Or, to be more precise, our existence has climate impact according to how our food is produced, and biking is like an intensification of our existence. Riding a bike is certainly more biospheric than driving a car—the biosphere made our bodies, and it’s great fun to use them—but ultimately riding can only be as biospheric as our food.
It might be surprising that four meat-eaters on a long-distance bike trip would emit less if they shared a hybrid car. But the take-away message shouldn’t be “cars aren’t so bad.” It should be “our food system is awful!”
Sharon rides 40 or 50 miles per week, most of it on her bike-plus-train commute to the University of California, Irvine. I asked her for her perspective as a woman bike-commuting on urban streets.
“As a woman commuting to work, I need to bring an extra outfit and be willing to mess up my hair.
“I need to carry my bike up and down stairs in the train stations, because the elevators are slow and crowded. It’s always hard to find space on the train, especially at rush hour. Some people are grumpy, and some are helpful.
“When I get on my bike, I feel as though I’m putting myself at risk. There’s one part of my ride where I say to myself, ‘This is the dangerous part.’ I have to cross several lanes of traffic coming off the freeway in order to get to the bike lane on the far side. We need some actual bike infrastructure, not just arrows painted on the street.
“People don’t bike because everything about our infrastructure is designed for the convenience of cars. Biking is an uphill battle. It’s easy to jump in a car, but biking requires planning and maybe even a kind of underground knowledge.
“Despite it all, I like to bike. It’s fun, it’s healthy, and it involves me in the sensual embodied world even more than motorcycling does. It’s delightful to go from Altadena to Irvine without using a car.”
For those who don’t bike yet, I urge you to put down this book and go for a short bike ride. If you don’t own a bike, borrow a friend’s or take a test ride at the local bike store. I think you’ll be happy you did. For the rest of you, bike on!