The Bicycle of the Future

This last section will be a somewhat more personal interpretation of the bicycle and its role in the future. To be quite honest, I doubt whether future bicycles will look very different from those of the present time. Similarly, I would answer the question about the future of the bicycle less wildly enthusiastic than some of my environmentally hopeful friends. Of course, I may be badly mistaken in these predictions — and indeed it would make life more interesting if I were. But most of what is being projected had as fair a chance in the past as it ever will in the future; if they didn’t make it then, why should they make it now?

Most of what I call the Bicycle Fiction images that are conjured up by those who see a golden future for two- wheeled self-propelled transportation are totally unrealistic. They present visions of a world with roads dominated by sleek pedal-driven cars, with overhead monorails in which the passengers sit merrily pedaling away, while fully enclosed recumbents dart by on separate bicycle paths. From the air, the whole pedal-driven mess is being controlled by police in human-powered helicopters.

The underlying assumptions are so unrealistic as to make this vision a sure loser. In fact, nowhere today are we any closer to realizing any of this in practice than we were when such concepts were first drawn up in the 1950’s. In this section, I will present my own expectations for the future, comparing them, as well as the premises on which they are based, with those of my more optimistic or imaginative colleagues.

Such visions are all based on unrealistic assumptions. One of these assumptions is the total collapse of external energy sources, combined with a sudden desire on the part of the populace to maintain their mobility on the one hand, while accepting the need to provide the requisite propulsive power themselves. The alternative, and more popular vision, is the one by which bicycles and other human powered vehicles become so much more attractive that those who now drive around in cars will be converted to the cause of self-propulsion. The one is as unlikely as the other.

18.1. He was going to revolutionize the bicycle industry: European designer Colani. Other than some balsa wood models, nothing remains of these grandiose plans. If you have read this book, it will not be difficult to appreciate why, looking at this photo.

18.2. Fully enclosed recumbent on three wheels. This Euro-Vector is still one of the world’s fastest HPV’s. Interestingly enough, the aerodynamic shape of this one was not computer-generated, as was the original US Vector but ‘eyeballed’ by the German physicist- frame builder Hans-Christian Smolik.

Human Powered Vehicles

Let us first take a closer look at the presumed prototype of tomorrow’s vehicle, the HPV, or human powered vehicle. Although most interest in these sleek machines was generated since the 1970’s, similar concepts have been around since record attempts were first made on streamlined bicycles by renowned bicycle racers before the outbreak of the First World War.

In addition to the things said in the preceding section about the concepts on which these machines are based, we should take a look at their actual form and use as developed until now. Whether another 10, or even 100 years of development will lead to such improvement that they will lend themselves to mass use can perhaps best be judged by extrapolating their development to date.

In the HPV races that are held regularly under the auspices of the IHPVA (International Human Powered Vehicle Association), some impressive speeds have been reached by such machines — at the time of this writing the record stands at about 105 km/h (65mph). That’s in an all-out sprint with a flying start over a distance of 200m (650ft) — quite impressive when you realize that regular bicycles in competition reach speeds of 70km/h (44mph) over similar distances.

Although the speed reached over such a short sprint obviously says something about the vehicle’s aerodynamic properties, a more practical measure is the speed reached continuously over a longer distance. Even under such conditions, as established in the one hour time trial, the HPV’s performance is quite impressive. So far they have improved on the records established on regular machines by about 25%, and these higher speeds were achieved by non-super-athletes.

Even so, that’s after nearly eighty years of development, of which the last twenty were quite intensive, with inter national cooperation and commercial sponsorship. Percentage-wise, the hour record on regular bicycles (presently more than 52km) has been improved about as much during the last 75 years as that on HPV’s.

18.3. This HPV was raced successfully as early as 1914.

18.4. Four-wheeled cruiser. Although it offers weather protection and looks sleek, it is sluggish and clumsy — hardly the transport of the future.

The Cycling Power Equation

All work on HPV’s aimed at optimizing the speed reached on them is based on a comparison between the available propulsive power and the power required to overcome the resistances of the bicycle. The ultimate speed can be determined by equating the two. The total resistance that must be overcome when cycling is comprised of the following components:

- Rolling resistance of the tires on the road surface.

- Air resistance, or drag, of bike and rider relative to the surrounding air (with or without wind).

- Friction resistance of the bicycle’s various moving parts

- Resistance against acceleration, determined by the inertia of the moving mass of bike and rider

- The effect of gravity when going up (or down) hill.

When all these factors are considered, the required power output can be determined from the following (simplified) formula as a function of speed and acceleration:

P=v (Fr+Fd+Fg+0.5a² m) η

Where:

For conditions of steady speed and level road, the acceleration and gravity factors can be left unconsidered, leading to the following simpler steady-state, level road formula:

P = v (Fr + Fd) η

HPV’s have to get their improvement over the regular bicycle out of a reduction of the air drag value, Fd in these formulas. Everything else can be improved at least as easily on a regular bike as on an HPV. Take weight and mass, which are invariably lower, or more favorable, for the regular bicycle than for the HPV. The other factor is rolling resistance, which is easier to minimize without undue discomfort on a road bike than lying flat in an HPV. Fig. 18.6 summarizes the results on a level road at steady speed for a number of different machines: regular bike in upright position, racing bike in low crouched position, and HPV.

18.5. Colani’s dream HPV. Although it is optimistically marked with the inscription ‘100km/h,’ it never got to be more than a scale model.

18.6. Relationship between output and speed as a function of bicycle type.

18.7. Today’s track racer still looks remarkably much like a conventional bicycle, despite disk wheels.

The cyclist’s output, here referred to as P followed by a number, must be equated to the value for P to calculate the speed v. It has been found that cyclists can be divided into three categories, each with particular riding habits and power output level:

- The casual and utility cyclist: Pc1 = 60W

- The fitness or fast recreational cyclist: Pc2 = 150W

- The racing cyclist Pc3 = 250W

These values are represented in Fig. 18.6 as horizontal lines. Wherever such a line intersects the curves for the required output, the speed reached by that cyclist with that bike can be read off. The HPV brings an advantage only to the racer, while the casual or utility cyclist does not reach a noticeably higher speed on the HPV than he does on the racing bike — in fact, this person would benefit considerably more by replacing his utility bike by a racing machine. Thus, the UCI regulations, which until 1990 prescribed the limits of design dimensions for bikes used in sanctioned races, can not be blamed for stagnating development.

Curiously enough, this is exactly the public the propagators of the future bicycle millennium have in mind: the non-cyclist or hitherto casual cyclist who has to be dragged from behind the steering wheel of his car to appreciate the virtues of self-propulsion. Fitness and racing cyclist ride bicycles anyway, they are quite satisfied but are too small in overall numbers to make much of an impact on the overall situation. In addition, HPV would need more development than they have undergone to date if they are to be made roadworthy and practical. So far, none of them are much good when ridden on public roads — and even less so when faced with the non-riding situations bicycles are exposed to, including storage and transportation.

18.8 .Three years of work went into this experimental HPV at OldenburgUniversity’s Applied Physics Department.

18.9. Prof. Schondorf (left) of CologneTechnicalUniversity has developed some interesting human powered vehicles.

Comfort and Suspension

As described in Section 17, most of the concepts for tomorrow’s dream bike include the wish to sit back the way you do in a Porsche. If you’ve ever driven any distance in that kind of car, you may know that it is not as comfortable in the long run as it is exhilarating at first. On a bicycle, it makes even less sense than in a car, because you have to move your legs around and around.

Whatever else one tries to achieve, two goals remain essential: minimizing rolling resistance and keeping the whole structure as light as possible. Leaning back, there is no way you can be comfortable without additional suspension. Adding any kind of suspension negatively affects at least one, if not both of these criteria.

18.10. Wheel size and its effect on uneven surfaces. Smaller wheels have more ‘ups and downs.’

Thicker tires add weight, and if inflated less to increase their cushioning effect, the rolling resistance goes up too. For road use, all other kinds of suspension, though less effective, tend to have the same effect of in creased weight. The one place to use suspension is off- road, because on very rough surfaces, traction can be improved by means of a suspension, and the tires can be inflated harder, resulting in a reduced rolling resistance.

Of course, futurists also expect their utopian road bicycles to have more, rather than less, comfort compared to the conventional bike of yesterday. In the low-slung design that is taken for granted in most of these concepts, small wheels and a low body position are required. Both increase the need for an effective suspension, even to get the same comfort — much more so if a higher degree of comfort is required. All this adds weight and further complicates the machine. The effect of small wheels on comfort and energy recovery is illustrated in Fig. 18.10. You may also refer to the comments about this subject in Section 17. Another problem would be the fact that the low slung body position only works well if a restraint holds the rider’s back in place. But that then has to be designed in such a way that it allows the perspiration generated at the physical output level of cycling to evaporate.

18.11. A futuristic utility bicycle that is supposed to be practical — but not ridable, as the author found out when requesting a closer look at it.

The point I am trying to make with this example is that, to be practically suitable, any bike design that differs drastically from that of the conventional model requires so much in the way of other tricks as to become hopelessly complicated and often harder to handle.

Cycling Under Cover

Very similar to the arguments for the other aspects of the HPV and similar special designs are those in favor of enclosures. Since people drive around in cars that are covered, it is assumed they will be more easily converted to riding bikes if they are covered too. But cy cling can be hard work, generating enough heat to make any enclosure unbearable. Air conditioning can not be the answer: to remove the heat generated by the cyclist, approximately ten times the cyclist’s output has to be made available to the air conditioner that would be needed.

18.12. Dream bike of the fifties. Today, Benjamin Bowden’s plastic-bodied Spacelander is a much sought-after collector’s item.

There are other problems with this idea. Whereas a conventional bicycle is relatively insensitive to cross winds, the enclosed model is easily swept aside by a strong wind, even the air stream generated by a passing truck. Handling an enclosed HPV can be much more difficult than one might expect. The materials used must be very light, and are quite prone to damage caused either accidentally or by vandalism. And while today’s bike can be transported or parked relatively easily, their enclosed counterparts resist most attempts in that direction.

At least one experiment with the presumably practical use of a roadworthy versions of an HPV for commuting was carried out in 1981 during the otherwise laudable though short reign of the environmentally responsible Adriana Gianturco as head of Caltrans, the California state transportation authority. An early version of the 3-wheeled 2-rider Vector was ridden between Stockton arid Sacramento in California on a closed-off freeway lane.

The route did not really represent your typical com mute run, typically characterized by plenty of cross traffic, sharp curves and other obstacles. An entire infrastructure was provided, with (motorized) escort vehicles, changing facilities, transport into the city. And, of course, there were reporters and medics, traffic police and others standing guard. The result was proclaimed a great success and promptly buried in the files: the HPV had managed to complete the trip in 70% of the time required on a regular bicycle, at times reaching speeds of 80 km/h (50 mph) on level ground.

A success after all? Not really. Unless the state can be counted on to provide every commuter with enough training to bring up his speed to the point where an HPV is of any speed advantage. Unless whole freeway lanes are permanently blocked to other traffic to allow HPV’s to do their thing. Unless enclosed storage and changing facilities, shuttle service and police escorts are provided for every trip. Unless California summer weather can be guaranteed everywhere all the time.

Don’t take my skeptical approach too seriously, though. There may be sound reasons for some people to believe in, or at least dream of, a golden age for self- propelled transportation. There are understandable, if not substantiated, reasons to have faith in man’s perfectibility, which should also increase his appreciation of the bicycle as a means of transport (a hard one to sell in an age when cycling is equated with fitness).

Even if most of tomorrow’s bikes will look just like today’s machines, even if most people riding them will do so because they are a little different from the rest, there is nothing wrong with hoping some will choose different machines and some who prefer to drive their cars today may someday voluntarily choose to cycle. Just don’t expect either a social or a technical bicycle revolution — whether now or in the future.

18.13. Experimental plastic utility bicycle in motor-scooter disguise. This 1989 Batavus weighs nearly as much as its motorized counterpart.

18.14. Despite heavy funding from Volvo and the Swedish state, this Itera plastic bike didn’t live up to the expectations.