Some middle-aged Americans cannot remember a time before television. That's a chilling thought right there. 

How difficult it must be for them to visualize what evenings were like before Miltie, Lucy, Johnny, and Walter. 

Suppose there is some fictitious substance -- "televiseum," we'll call it -- which is necessary for the operation of all TV sets. If the world-wide supply of televiseum ran out, those middle-aged people would face a challenging adaptation. 

In the post-televiseum age, we would all have to get along with radio and books and various home-crafts for entertainment in the evening. Not too bad for those of us who look back with fondness to the pre-televiseum age. 

Almost nobody can remember a time before automobiles. Maybe that's why contemplation of a post-petroleum age is such a problem for so many people. 

But not for bicyclists.

When enthusiasts allege that the bicycle is faster than the automobile, they're usually basing the comparison on "economic speed." 

Such calculations take into account the fact that the average wage-earner spends a minute-and-a-half-at-work for each mile driven. That's about what is required to pay all of the expenses associated with operating an automobile. 

You might enjoy figuring out the economic speed of your own car. Be sure to amortize your fixed expenses and to include depreciation (a penny per mile for each grand in the purchase price) as well as other variable costs (gasoline, oil and maintenance). Don't forget that this all comes out of spendable income, the part of your earnings you don't start receiving each year until sometime in May (the first four months having been devoted to earning what you must pay in annual taxes). 

Unless you receive a huge salary and own a cheap car which you rarely drive, you too are spending upwards of a minute-and-a-half-at-work for each mile you drive your car. 

Thus, a car that averages 25 miles per hour around town takes about 2.4 minutes per mile. Adding this to the requisite 1.5 minutes-at-work gives a total of 3.9 minutes per mile. 

Now, a bicycle does only about 15 miles per hour or four minutes per mile. That corresponds to an "economic speed" approximately the same as for an automobile -- not faster.

When was the last time you saw a gallon of gasoline? 

Nowadays, gasoline is an invisible abstraction, represented in digits. 

Earlier in the petroleum age, they used to show you the stuff before you bought it. Remember those tall glass cylinders down at the filling station? You could actually see the pinkish liquid draining away, passing the gallon-marks, gurgling through the hose into your tank. 

A paradigm for our time.

Reducing automobile speed saves petroleum. It also saves lives. 

This latter point is now supported by global statistics. Countries with lower speed limits have proportionately lower fatality rates, generally measured as lives lost per 100 million miles driven. 

But it does take more time to go places at slower speeds. For the sake of discussion, let's adopt a new unit of time -- the "life-time." It amounts to 613,200 hours. (Take 70 years times 365 days times 24 hours and you get 613,200 hours in an average life-time. Surprise!) 

Thus, we can calculate how many life-times would be spent traveling, say, 100 million miles. The slower the speed, naturally, the more life-times it would take. 

There must be some speed at which the number of life-times spent just equals the number of lives lost in accidents per 100 million miles driven. There is. 

It's 56 miles per hour. 

Slower than that and you waste more life-times, faster and you lose more lives. 

Time is a non-replenishable natural resource -- whether measured in minutes, years, or life-times. It is not something to be wasted, apparently, in the act of driving. For, as you see, motorists choose every day to expend another non-replenishable natural resource, petroleum, to conserve life-times. 

At the appropriate cost in lives.

Cars save time. Automobiling is faster than bicycling, there is no denying that. 

Or is there? 

It depends on what you need the time saved for. If you need the time for healthful exercise, say, then the bike doesn't come out so far behind. 

If you need the time to earn money to pay for your car, then the bicycle may actually be, economically speaking, faster. 

If you're going to spend your time looking for parking or gasoline, or if you plan to fill your time saved watching "Bowling for Dollars,"... 

Enough said.

Don't bother to look for a better engine than the one you already have in your car. 

The reciprocating-piston, internal-combustion engine is the undisputed efficiency champion for automotive applications. It's called an Otto cycle, by the way, if it has spark plugs, a Diesel if it doesn't. Either way, you have the best possible kind for three reasons, each a sine qua non. 

First, there are the salutary consequences of having the combustion internal. What this means is, the heat gets converted to mechanical motion in situ -- right there in the combustion chamber. It doesn't have to go anywhere. 

In an external combustion engine like the old-fashioned steam locomotive -- and all the new-fashioned steam turbines -- the heat has to be transferred from where it's produced to where it's to be used. Huge inefficiencies result, particularly at low power settings. 

Second, the reciprocating piston has some superb attributes. Sure, there's a little vibration from those reciprocating pistons and rods. The much-touted Wankel rotary engine has no such vibratory components inside. Neither does the Brayton cycle, better known as the gas turbine. 

Well, our piston moves up and down in a cylinder and can thus produce any compression ratio the designer chooses -- nine, ten, whatever. You may not care about this, but the second law of thermodynamics does. Compression ratio is a first-order determinant of engine efficiency. 

The rotary engine is limited absolutely by its internal geometry to a compression ratio no higher than about six and a half. Rotaries always lose efficiency contests with the reciprocating-pistons. 

So do turbines. They're okay in high-power "cruising" applications such as in aircraft -- jet engines are turbines. But for start-stop driving, be glad you have reciprocating pistons. Besides modern automobile engines have fully overcome vibration with ingenious counterweights and balance shafts. 

Third, there's what might be called 'commensurate flame velocity." That'll take some explaining.

"What is the greatest invention in the world?"

There's an intermittent fire that bums in each combustion chamber of your car's engine. (You may have thought of it as an explosion, but fire is a better term.) At 55 MPH. Each fire is ignited about 25 tunes per second. 

If you could view the burning in slow motion, you'd see the flame moving across the face of the piston from the point of ignition toward the cylinder walls. The fire lights up, rushes through the combustion chamber, and goes out -- all while the piston is virtually stationary. 

Now, here's an amazing -- and important -- thing. 

The flame velocity is not a constant. It varies with the speed of the engine. When the engine runs faster, the flame burns faster; when the engine runs slower, the flame burns slower. How does it know? 

All right, amazing -- but why important? 

"Commensurate flame velocity" gives the reciprocating-piston, internal-combustion engine its most distinguishing feature, dynamic range. You may correctly surmise that the term "dynamic range" was borrowed from high fidelity sound reproduction technology. There, it denotes the ability to accommodate faithfully a wide variety of sound intensities from soft to loud. 

As used here, we mean that for an engine to be endowed with dynamic range, it must accommodate faithfully a wide variety of speeds and loads such as are experienced in the automotive application. Low power demands must be met with low fuel consumption, and high with high. 

The reciprocating-piston engine does this better than any other kind in the world. If it were not for this single feature, the automobile would never have become practical. 

Imagine -- no highways, no suburbia, no drive-throughs, no displacement of the bicycle. 

By the way, for quite a long time experts were really not sure how the engine "knows." The solution to the mystery is something of a mouthful: Flame speed adjusts itself to the engine speed as a result of compression enhancement of inlet induced charge turbulence. 

Now both you and your engine know.

Please excuse some bicycling zealots for their tactless ridicule of America's pickup truck fleet. 

Those boisterous tall-tired machines bring new dimensions to trucking. Take that dwarfed truck bed, for example. Notice how it contrasts with the outsized fenders and the requisite roll bar. 

What you see is an expressive art form -- not prosthetic machismo. 

Let's enjoy these sculptured marvels while there's still enough gasoline to move them.

Whose oxygen are you breathing right now? 

Much of it comes from green plants nearby. During the daytime, their leaves store solar energy by "fixing" carbon out of atmospheric carbon dioxide. It's called photosynthesis, and oxygen is a byproduct. Day and night, the green plants metabolize part of the stored energy. But there's plenty of carbohydrates left over for us and other plant-eating "parasites" to consume. 

We need to breathe that oxygen, too. 

So does the engine in your automobile. About a pound of oxygen per mile. That's an order of magnitude more than a bicyclist consumes. 

Some countries drive more than their share of automobiles. The green plants nearby may not be able to supply all the oxygen they need. Oxygen must be imported from somewhere else. 

The Amazon jungles have plenty of green plants, but few automobiles. 

Maybe you're breathing Brazilian oxygen.

Approaching the post-petroleum age, we hear a lot of talk about 0-L-S, our-life-style. 

0-L-S, it seems, is what we must preserve. Any alternative energy source is okay so long as it doesn't affect 0-L-S. 

Yet petroleum once was an alternative energy source, and think of all the changes it made in 0-L-S. Plastics, for example, come from petroleum, and it's hard to imagine telephones, transistors, or fast foods without plastics. In the past we've embraced 0-L-S modifications unafraid. 

Take the automobile. It certainly applied petroleum and imparted a whole new 0-L-S unto us. Some now fear its loss. 

One of the most promising alternative energy sources for personal transportation is muscle power. The consequent 0-L-S is reasonably familiar. 

Particularly to bicyclists.