few years ago, some of my col-leagues started commuting to

work on their bicycles. Even-tually, I realized that some of them were riding longer distances than my commute would be, and I decided to give it a try. The first ride was dif-ficult and took quite a bit of time. But I kept at it and came to enjoy it. I’ve been commuting by bike two or three days a week for the past four years. These long rides give me plenty of time to ponder things, and one of the things I’ve pondered is if it makes economic sense to commute by bicycle. On the surface, it seems like a straight-forward question. But the more you think about it, the more com-plicated it becomes.

Let’s start with some background parameters. My commute by automo-bile is 31 km (19 mi), mostly on major highways in the Boston area. I can’t take the same highways by bicycle and wouldn’t want to. By bicycle, I take

back roads and even a stretch of a bicy-cle path, and my route is actually more direct. It’s about 26 km (16 mi). Liv-ing in New England, the weather isn’t always conducive to bicycling. There are some hard-core cyclists that have

studded snow tires for the winter. I do not. I will ride when the temperature is as low as –9 °C (15 °F) but not in the snow. I also avoid riding in the rain. In the end, I commute by bike about 38% of the time, so I need a car for the rest of the time. Presumably, biking some days will let my car last longer and reduce my maintenance costs. And I save money on gas. Let’s start looking at specific costs.

Equipment CostRather than get into the detailed costs of operating a car, I’ll use a lumped

sum. The American Automobile As-sociation currently estimates the all-inclusive average cost of operating an automobile in the United States at US$0.363/km (US$0.585/mi). The U.S. Internal Revenue Service allows a cost

of US$0.34/km (US$0.55/mi) for tax purposes. I don’t have a large or fancy car, so let’s use US$0.31/km (US$0.50/mi) for my cost. I don’t pay any tolls on my drive to work, so that means that the cost for me to commute by car is US$19.00/day. That’s a surprising-ly high figure.

There is no easy way to calcu-late the cost of operating a bicycle, so we’ll have to do it item by item. After commuting on my old, run-

of-the-mill bike for a year, I decided to buy a nice road bike. It is a little more comfortable than my old bike was and quite a bit faster. I paid close to US$1,500 for the bike plus some acces-sories. If well maintained, the bike should easily last ten years. There are also maintenance costs. I like to have a professional look it over once a year. There are also components that wear out—tires, tubes, chairs, gears, bearings, brakes, etc. I’ve spent about US$1,200 maintaining my bike over the past three years, or about US$400/year. I’ve also bought

12 July/August 2012

The Economics of Bike Commuting■ Fred Schindler

Digital Object Identifier 10.1109/MMM.2012.2197139 Date of publication: 11 July 2012

Fred Schindler (m.schindler@ieee.org) is with RF Micro Devices, Billerica, Massachusetts

A

© STOCKBYTE

14 July/August 2012

additional accessories and upgrades—lights, gloves, helmets, bike clothing, new handlebars, etc. That has totaled about US$750 over the past three years, but much of it is for items with a usable life longer than three years, so let’s estimate the annual cost at US$125.

If we amortize the cost of my bike over ten years and add the annual cost of maintenance and accessories, it comes to US$675/year. I’ve managed to ride close to 4,850 km (3,000 mi) each of the last three years, so the cost is US$0.14/km (US$0.225). That makes my equipment cost US$7.20/day for commuting by bike.

FuelThe fuel cost for an automobile is in-cluded in the lumped sum mileage cost of US$0.31/km (US$0.50/mi). A bike doesn’t use any fuel. But I do. There is no question that I am quite a bit hungrier and I eat quite a bit more food when I ride my bike. I haven’t kept a tally of what I eat every day, so I’ll have to make an estimate. The cost is modest. I don’t go out and have an extra res-taurant meal. But I will have larger servings and eat some snacks on days I bike. I’m sure the amount I con-sume and what it costs varies quite a bit from day to day. Some days, coworkers bring in leftover treats from home, and I can partake heartily for free! My best guess is that on average I consume an additional US$3.00 of food and drink per day I commute. Add that to the equipment cost, and we are now up to a total of US$10.20/day commuting.

TimeTime is money, and it takes longer to pedal a bike than to drive a car. On a good day, my commute by car takes about 30 min. My commute by bike takes about 55 min. That’s a 25 min difference per trip, or 50 min per day. I also need to shower and get changed

after I ride my bike, once when I get to work and once when I get home. On days when I drive my car, I still have to shower and get dressed once, so there is a net increase of once per day. Let’s say that takes 15 min, making the dif-ference between car and bike about 1:05 per day.

Before I started commuting by bike, I would go running for exer-cise, also two to three times per week. Usually I would do this during lunch break at work. It would take me about an hour to run, shower, and get dressed. I now get quite a bit more exercise by biking instead of run-ning. Accounting for the time I no longer spend running, I have a net time penalty of 5 min.

But there is one more consideration. The commute by car is not predict-

able. In normal con-ditions, it takes me 30 min. On the very best of days, it can take only 25 min (a rarity). On bad days, it can take 45 min or even as much as an hour. I have n’t calculated the average time, but I sus-pect 35 min is a good estimate. The commute by bike is much more predictable. Traffic is not much of an issue. Weather (wind and temperature) can have

an effect, as can how I feel. But unless I have an equipment failure, the range is between 49 and 58 min. I maintain my bike well and use very good tires (see “Surprised Bike Maintenance Costs So Much?”) so equipment failures are rare.

In the end, there isn’t a significant time impact on my life if I commute by bike instead of by car. This is largely because it allows me to dispense with running for exercise.

HealthHealth and medical expenses are a tricky area. Certainly, riding this much on a bike has improved my health—my weight has decreased, my cholesterol is lower, my heart rate has come down, as well as my blood pressure. These

Time is money, and it takes longer to pedal a bike than to drive a car. On a good day, my commute by car takes about 30 min. My commute by bike takes about 55 min.

18 July/August 2012

Casual bike riders tend to think of a bike as something that requires little or no maintenance—all you have to do pump up the tires and oil the chain from time to time. Once you start riding thousands of kilometers (or miles) you realize that it’s not so simple—lots of things can and do wear out.

TiresTires can be bought for as little as $US10 each, and that’s probably what the tires that come with a bike are worth. But after commuting for a few months, you come to realize that it’s worth spending more on low-resistance and puncture-resistant tires. Before I bought puncture-resistant tires, I averaged a flat every 300 km (200 miles). It takes about 20 min to replace a tube (10 min if you get really proficient). Good puncture-resistant tires cost about US$50 each. A good set of tires lasts about 5,000 km (about 3,000 mi), so, about a year for me. At 5,000 km (3,000 miles), the tread of the rear tire is mostly worn way at the center, and the sidewalls show wear. You can ride longer, but cornering performance decreases and there is an increased risk of flats. The front tire wears much more slowly, so switching tires front to back can extend the useful life. (Send me an e-mail if you want my views on the performance of different tire brands.) My annual cost for tires has been US$100 (though I could reduce it to as little as US$60 by using the tires longer).

ChainsChains wear out. It’s called “chain stretch,” but it’s really wear in the bushings and pins that hold the links together. A well-maintained chain (which means frequent cleaning and careful lubrication) lasts about 5,000 km (3,000 mi). A poorly maintained chain will only last a third that distance. What happens when a chain wears out? The chain will no longer mesh properly with the sprockets (gears) and will occasional miss or skip. Eventually, it becomes unridable. A good chain costs US$30 (though it’s possible to spend more than three times that). My annual cost for chains is US$30.

CassettesThe cassette is the collection of sprockets on the rear wheel. These also wear out. A worn chain will reduce the life of the cassette. Many people recommend changing the cassette whenever you change the chain. I’ve been able to get two chain lives from my cassette. A good cassette costs US$70, though it’s possible to spend US$400. My annual cost for the cassette is US$35.

Brake PadsI manage to wear out a set of brake pads about once a year. My annual cost is US$10.

CablesThere are cables that control the brakes and the shifting mechanisms. I’ve had one fail per year. Though a cable

only costs about US$15, mine have always failed at inopportune times, so it’s been most expedient to have a bike shop replace them for about US$50. My annual cost is US$50.

Bottom BracketThe bottom bracket is that part of the frame that the pedals crank around. It’s also the name for the bearings for the crank. As you can image, they get a fair amount of wear. Mine lasted about 8,000 km (5,000 mi), though I suspect they would have gone longer it I’d been more careful maintaining them. A good bottom bracket costs US$75, and I’ll set my annual cost at US$30.

WheelsWheels don’t generally wear out, though they can be damaged by a large hole in the pavement and by neglect. The spokes need to be checked and tightened as necessary to keep the wheel in true. Then there are the bearings in the hubs. The rear bearing gets considerable wear. Mine started to fail at about 10,000 km (about 6,000 mi). The labor of replacing a bearing is considerable, and the original wheel on my bike was of modest quality, so I opted to replace the entire rear wheel for US$120. My annual cost is US$60.

Tune-UpMy local bike shop will give the bike a thorough once-over for US$70. This included adjusting everything as required, including the spokes. It costs more if anything needs to be replaced. My annual cost is US$70.

Cleaners and LubricantsI use a solvent to clean the chain about every 300 km (200 mi). I also have oils for the chain and the various bearings. My annual cost is US$40.

This brings my total annual maintenance cost to US$420. I’ve dropped this to US$400 for my cost per commute calculation because I believe some of my replacement parts will last longer than the original parts, and I can make my tires last longer. Of course there are a number of parts that can wear out that I have not yet replaced, so I don’t really know what they’ll contribute to by annual cost. This includes: the pedals, since they have bearings (US$35); the front wheel (US$120); the crankset (US$150); the rear derailleur (US$80); and the front derailleur (US$20). There are other parts of the bike I can imagine wearing out, including the seat (US$80), the bar tape (US$20), and the shifter/brake levers (US$280). My bike frame is mostly aluminum with a few pieces of carbon fiber. It all looks very solid after about 15,000 km (about 9,000 mi), but I wonder if it may eventually show signs of fatigue. Considering all this, US$400 per year is a good low estimate for my long-term maintenance costs.

Surprised Bike Maintenance Costs So Much?

20 July/August 2012

should all be good things for my long- term health, but I have no good way to monetize this. In the long run, I should save on my medical costs, but how much? Besides, most of the saving will go to my medical insurance provider. I may also live longer, but there is no good way to estimate how much longer and how valuable that will be.

There is also a downside. Bike rid-ers have accidents. They are rarely life threatening, but there can be signifi-cant trauma. I have a neighbor that has been commuting by bike for about 30 years. He has had two major acci-dents involving cars where he’s needed surgery. In my limited time riding, I’ve had one accident. I man-aged to do so without anyone else’s help. I turned too fast on a patch of sand and fell very hard on my side. I ended up with a nasty clavicle fracture that required surgery and a couple of cracked ribs. I don’t know what the total cost was; my insurance company paid most of it. My share was in the hundreds of dollars.

There are also potential chronic is-sues from bike riding. Generally, riding a bike does not cause difficulty in the joints or the back, but heavy usage can al-ways be an issue. My knees used to both-er me quite a bit when I ran for exercise, but now they don’t. But now one of my hip joints tends to get mildly irritated. The worst impact can be on the wrists and the hands. There can be quite a bit of pressure on the hands, though a good bike fitting will minimize that. Road vi-brations are telegraphed up to the hands from the front wheel through the han-dlebar and can cause problems similar to repetitive use syndrome (carpal tunnel). Good gloves, handlebar, padding, and bar tape can minimize this.

So in the end, it is difficult to quan-tify the health benefits and liabilities of bike riding. I think it’s fair to say they offset each other and the net impact on cost is close to zero.

Other StuffI thought it would be interesting to look at the difference in carbon foot-

print between biking and driving a car. I suspect there is a significant car-bon impact from manufacturing my car, as well as a smaller impact from manufacturing my bike. Since I would own my car regardless of my biking, I think we can ignore the manufactur-ing impact. That mostly leaves fuel to consider. My car uses about 5 L (1.3 gal) of gasoline per day I commute. According to Wikipedia, combustion of gasoline releases 2.3 kg/L of CO2 (8.8 kg/gal), so my daily commute re-leases 11.5 kg of CO2.

The calculation for bike commuting is more difficult. I’ve tried a wide range

of tools to try to esti-mate how much energy I burn per day com-muting by bike, and the results vary wildly. A good median result is that I use about an ad-ditional 1,000 calories (more correctly 1,000

kcal) per day I bike. Assuming I replen-ish that with food, we need to figure out how much CO2 1,000 calories of food contributes. Here again, there are wildly varying estimates for the car-bon released by making food. It varies depending on the way the calculation is done and on the food. In the end, I decided to simply average the results for a wide range of foods (ranging from 1.1 to 8.9 kg per 1,000 calories) giving a result of 5.3 kg per day I bike. If I was a vegan, apparently I could cut that in half.

There is also the impact of the eco-nomics and politics of energy. In the United States, most of our petroleum comes from Canada. That means I am supporting that hockey-obsessed land of the north when I drive! Seriously, the petroleum market is global, and many of the major petroleum export-ing counties have political agendas I’m not fond of, so I do think reducing the gasoline I consume is a good thing. Of course, a fair amount of the petro-leum I save by not driving goes into the petroleum used to produce of the food I consume, but overall there is a mod-est net savings.

(continued on page 32)

There is also the impact of the economics and politics of energy.

32 July/August 2012

first message transmitted repeatedly was the binary-coded word “NEU-TRINO.” The data received consisted of 3,454 records spanning an interval of 142 min. “An overall data rate of about 0.1 Hz was realized, with an error rate of less than 1% for transmission of neu-trinos through a few hundred meters of rock” [1].

Such neutrino-based communication systems have been proposed (but not demonstrated) for electromagnetically challenging environments such as a sce-nario involving a submerged submarine [5]. Of course, a neutrino detector will have to shrink a great deal in weight before that enters the realm of possibil-ity. But, before we dismiss the concept of neutrino-based communication itself, we should think about what happened to Hedy Lamarr and her invention in 1942 of a frequency-hopping radio-con-trolled system for guiding torpedoes. As I described in [6], Hollywood actress

Lamarr and her coinventor George Antheil (a composer) had proposed a player-piano mechanism as one pos-sible implementation of the frequency-hopping system. Antheil later wrote “In our patent Hedy and I attempted to bet-ter elucidate our mechanism by explain-ing that certain parts of it worked like the fundamental mechanism of a player piano. Here, undoubtedly, we made our mistake. The reverend and brass-headed gentlemen in Washington who examined our invention read no further than the words ‘player piano.’ ‘My God,’ I can see them saying, ‘we shall put a player piano in a torpedo.’… In 1962, three years after the Lamarr-Antheil patent had expired, ships equipped with secure military-communication systems, based on the frequency-hop-ping technique, were deployed during the Cuban missile crisis” [6]. So, even neutrino phones may someday see the light of day.

References[1] D. Stancil et al., “Demonstration of communi-

cation using neutrinos,” Mod. Phys. Lett. A, vol. 27, no. 4, 2012.

[2] (2012, Apr. 6). ET, phone home, The Economist [Online]. Available: http://www.economist.com/node/21550242

[3] J. Aron. (2012, Apr. 6). Neutrinos send wire-less message through the earth, New Scientist [Online]. Available: http://www.newscientist.com/blogs/shortsharpscience/2012/03/ neutrinos-send-wireless-messag.html

[4] R. Boyle. (2012, Apr. 6). For the first time, a mes-sage sent with neutrinos, Popular Sci. [Online]. Available: http://www.popsci.com/science/article/2012-03/first-time-neutrinos-send-message-through-bedrock

[5] J. Hsu. (2012, Apr. 6). Neutrinos may someday provide high-speed submarine communica-tion, Popular Sci. [Online]. Available: http://www.popsci.com/military-aviation-amp-space/article/2009-10/neutrinos-may-some-day-provide-high-speed-submarine-commu-nication

[6] R. Bansal, “He(a)dy stuff,” IEEE Antennas Prop-agat. Mag., vol. 39, no. 3, p. 100, June 1997.

MicroBusiness (continued from page 20)

We already went over health and medical costs. How about more general well-being? I ride on roads with cars and trucks. Do I feel ner-vous and endangered? Actually not. For the most part, I find driv-ers in the Boston area to be very considerate of bike riders. It helps that there are more bike riders every year. There are also intangible well-being effects to consider. How does riding a bike 52 km (32 mi) impact the rest of the day? It does help me sleep well! How about fatigue? When I first started bike commuting I would be exhausted when I returned home in the evening, and wouldn’t

really be interested in doing much more for the day. Now that it’s become part

of my routine, I don’t think that is much of an impact. I have plenty of energy to do whatever I want in the evening.

Summing UpBased on the vari-ous comparisons I’ve made, it does appear I come out even or ahead in every cat-

egory. The difference is not as great as I first imagined. I’ve made a bunch of estimates and approximations, so we don’t really know the actual cost. The US$0.31/km (US$0.50/mi) estimated cost of operating a car is all inclusive,

but many of those costs hold even if I reduce the distance I drive the car ev-ery year. The other extreme is to only consider the incremental cost, which comes down to fuel expense. Fuel costs have varied quite a bit over the past few years. As I write this, gasoline cost is approaching US$1.06/L (US$4.00/gal). That makes the incremental cost for me to commute by car per day about US$5.25. If the cost of the added food I consume per day is US$3.00, it still looks like an advantage to commute by bike.

Of course, I don’t really ride my bike to work for economic reasons. I do it because I enjoy it. I spend an additional two hours outdoors, mostly on nice days, and I stay quite fit. I notice more and more people riding their bikes early in the morning and evenings, so I don’t think I’m alone.

Based on the various comparisons I’ve made, it does appear I come out even or ahead in every category.