As I write this (6-2012) the price at the pump has Dropped to somewhere in the neighborhood of $3.30 / g. I guess I’m suppose to feel good about that. It’s amazing how much of the price is tax. The incredible automobile continues to become more and more efficient which is great for mother earth but don’t expect to save any money at the pump. With increased efficiency under the hood less fuel is being bought resulting in less tax revenue. Our lawmakers, not being very efficient, will have to make up these losses by raising the gasoline tax. Also proposed is a tax based on miles driven. The simple solution for me is to ride my bike.
What’s the MPG equivalent of me on my bike? “How Things Work” has concluded that riding a bicycle is equivalent to 912 MPG when compared to the automobile. 1 gallon of gas = 31,000 calories. When How Things Work factors in the losses (weight, drag, resistance) it drops to about 300MPG.
If you enjoy math try this. Tom Murphy is an associate professor of physics at the University of California, San Diego. His blog post entitled “MPG For A Human”, how efficient are humans at moving ourselves about, takes a look at how to convert miles ridden on a bicycle to MPG . Here are just a few of Professor Murphy’s calculations and conclusions.
“On one extreme, we could use a gallon of lard for our fuel. Though not a delight to eat, at close to 2000 kcal/$, lard is probably the best value in the grocery store in terms of energy per dollar (just a guess). This is truly the closest thing we could get to eating a gallon of gasoline proper.”
“So depending on the mode of biking and how you want to do your accounting, we got about 290 MPG in town, 160 MPG on the open road. Converting to the more universal and useful measure of energy per unit distance, these numbers map to 5 kWh/100-mi, and 2.8 kWh/100-mi. For comparison, electric cars turn in performances around 30 kWh/100-mi, and a 40 MPG car uses 90 kWh/100-mi (but beware a direct comparison between these last two: if the electricity is derived from fossil fuels, the fossil fuel investment becomes similar for the two: ).” Notice how the in town MPG is better than the open road MPG, just like a Hybrid car.
Fly in the Ointment
“Our walking or biking economies look pretty decent stacked up against cars—especially if we considered consuming foodstuff as potent as gasoline. This is all well and good until one appreciates that because of the way Americans grow, harvest, distribute, and prepare their food, every one kilocalorie of food eaten has consumed about 10 kcal of fossil fuel energy (dominated by oil). Our 7000 kcal gallon of food therefore took 70,000 kcal of fossil-fuel energy to produce, or a little over two gallons of gasoline. So you would divide the “food economy” values we calculated by 2.2 to get the fuel economy that supported your bike trip or hike. Now walking consumes 18–34 MPG of oil equivalent, and biking comes in at 70–130 MPG.”
Only alluded to in his post was the efficiency of four passengers in a very efficient car. Without figuring in the loses due to added weight it would be 40 mpg x 4 =160mpg. What about one of those buses that runs on natural gas hauling fifty people? Let’s just pull a number out of thin air and give the bus a 5 MPG x 50 passengers equal to 250MPG. The bicycle still looks very respectable. (For the complete analysis please read professor Murphy’s blog. Very thought provoking stuff.)
Well………I’m just a guy riding a bike. I struggle with writing, spell check continues to show me how truly ignorant I am and math makes my head hurt, although I’m pretty good at calculating the tip. There is money to be saved by riding my bike although how much depends on the cost of the “human fuel” required to ride, yes required. When fitness increases so does efficiency, less fuel to do the same amount of work. I wrote about this in the past, see my post Calories Burnt Per Mile or Please Santa Bring Me a Garmin. Lets move on.
Talk about inefficient, I’ve recommissioned my heavy road bike and plan to use it as a commuter. The grocery store, the library, the local hardware store and the swimming pool are all places I can easily reach by bicycle. I put a rack on the back , as if it wasn’t heavy enough. I made a 1/4 pound bike lock out of stuff laying around the garage, just to keep the casual thieves away. It’s an old bike but it’s mine. I thought about taking it on a trip but………nah. I just need to minimize the stuff I need and figure out how to carry it on my carbon road bike.
Human MPG is just the tip of the iceberg when it comes to saving money by riding a bike. Total cost of ownership is MPG + all the other cost /miles on the odometer. I need to look at that at some point. I think I’ll be pleased when comparing it to the cost of ownership of my truck, at least until our law makers find a way to tax the bicycle. Don’t Tread On Me!
Thanks for reading my stuff and for all the great comments received by my previous post. Keep in touch.