The modem bicycle did not come falling out of the sky. A complex and interesting process of technical development has taken place since the German baron Karl Drais zu Sauerbronn (usually referred to as Von Drais) developed his walking machine — the first recognizable predecessor of today’s bicycle. Understanding this process of development will help achieve a thorough understanding of the technical aspects that are relevant to today’s bicycle.
Only with the knowledge of the historical development and the many systems and concepts that have been integrated in the process, will it be possible to fully appreciate and evaluate the technical developments of today. Conversely, it will facilitate a sober look at concepts that are presented as new, revolutionary improvements. Only too often, these represent non-solutions for problems that are incorrectly perceived. Or they may amount to nothing more than a new version of an old idea that had failed before — usually for sound technical reasons. An informed bicycle rider is not easily fooled.
The laws of physics have not changed in the more than 170 years since the first bicycles appeared. And remarkably, much of what makes for the quality of a bicycle is simply a matter of applied physics. Phenomena ranging from the rolling resistance of the wheels to leverage of the cranks, from the power of the brakes to steering and maneuvering, are all simple mechanical matters that can be understood, calculated and influenced by rational methods. A sober view of these subjects can contribute significantly to guide future development in the right direction, lest we waste time and resources trying to solve problems that don’t exist or that are fixed by the laws of nature.
The First Bicycle
The bicycle Von Drais introduced in the year 1817 was a wooden two-wheeled vehicle that weighed some 45 kg (100 lbs). It comprised a wooden beam structure, straddled by the rider, with a fixed wooden rear wheel and a steerable wheel in front, controlled over a tiller mechanism. It was propelled by pushing off with the legs, rolling along between these propulsive pushes.
Accounts according to which a certain De Sivrac was supposed to have invented a similar, though un steerable, vehicle some 20 years earlier were proven to be false, but were unfortunately copied from one book to the next. Even Leonardo da Vinci never built (or even drew) the vehicle in which some see a bicycle that was depicted on the back of an original manuscript page. In short, it is sale to say Von Drais was indeed the first person to perceive the idea of the bicycle — two-wheeled, human-powered, single-track propulsion.
Despite the technical and visual development the bicycle has undergone in the years since, the basic concept is clearly present in Von Drais’ invention, and what is more, unlike so many other ideas, this one was actually built and used in practice. The essential principle was the transition from an intermittent (walking) to a continuous (rolling) movement, which greatly reduces energy consumption, as depicted in Fig. 1.1.
1.1. Comparison of relative power output requirements of cycling and walking. Cycling is several times more energy-efficient than walking, since the body weight does not have to be raised with every step, as it is in walking.
1.2. Von Drais’ original bicycle of 1817
The most important principles of the modern bicycle were present in this machine: the idea of placing the two wheels in line and steering the front wheel. This al lowed balancing the inherently unstable vehicle through a combination of the effect of the inertia of the rolling mass and the direction of the steered wheel. In section 6, The Steering System, we will discuss this principle in more detail.
Everything that has changed on the bicycle in the intervening years can be regarded as refinements on the basis of this basic principle, rather than as new developments or even revolutionary concepts. How ingenious it was should be clear from the dramatic improvements it has allowed since its early days, without changing the basic concept. The maximum speed has gone from 15 to 50 km/h (10 and 30 mph, respectively), its weight from 45 to 9 kg (100 and 20 lbs. respectively). These improvements were due to a more refined choice of materials, more precise manufacturing techniques, detail improvements ranging from the use of ball bearings and pneumatic tires, and better road surfaces. Thus the overall efficiency of the machine could be raised from perhaps 40% to something more like 90%, meaning that the modern bicycle transforms some 90 watts of every 100 watt input into propulsive power.
1.3. Michaux’ velocipede (approx. 1860). This was the first commercially produced crank-driven bicycle.
The Crank-Driven Bicycle
Even during Von Drais’ lifetime, several ingenious tinkerers attempted to improve on the basic design by introducing some form of continuous mechanical drivetrain to replace the stepping motion. Although Gavin Dalzell (or, according to unsubstantiated speculative interpretation, Kirkpatrick Macmillan) built ingenious treadle-driven machines in Scotland, others simply connected foot-driven cranks to the front wheel. The first commercial application of this method was the one introduced and patented by father and son Pierre and Erneste Michaux of France in 1861.
The Michaux themselves, as well as others, worked continuously on refining the design and its mechanical details. This way, the total weight of a typical bicycle could be halved during the time from 1860 to 1870, due to the use of lighter, but structurally sounder construction techniques, and the rolling resistance could be dramatically reduced through the use of ball bearings.
But even this improved bicycle did not go much faster than its simpler predecessors as long as the wheel was driven directly. After all, the overall speed was deter mined by the pedaling speed and the circumference of the driven wheel. With a diameter of 70 cm (28’), the typical wheel had a circumference of 2.20 m (7’-4”). Even when pedaling at a rate of 80 rpm, the speed did not exceed 80 x 2.20 = 176m/min or 10.5km/h (6.5mph), and that is about the same speed Von Drais had achieved, even though the crank-driven bicycle required less effort.
1.4. Replica of Gavin Daizell’s treadle-driven machine, often attributed to Kirkpatrick Macmillan.
1.5. High-wheel, or ordinary, bicycle of around 1870.
On the newer, more efficient machine, the rider noticed a distinct excess power, certainly under favorable conditions — level roads with a firm, smooth surface. To exploit this excess power, it would be necessary to improve the drivetrain by increasing the ratio between pedaling speed and riding speed. The easiest way to achieve this was through the use of a larger diameter driven wheel. Made twice as big in diameter, its circumference would also be doubled, allowing twice the speed, even if at the expense of more effort.
This development, as well as several other technical refinements of the bicycle, took place mainly in England, which had become the center of the bicycle industry around 1870, when the French were more preoccupied fighting a war against Germany. Besides increasing the wheel size, many refinements such as tension-spoked wheels, tubular steel frames, as well as brakes and lights were introduced during this time.
1.5. High-wheel, or ordinary, bicycle of around 1870.
The Indirectly Driven Bicycle
Although the high-wheel bicycle, with its big driven front wheel, dominated the scene for a period of some 20 years towards the end of the 19th century, it was clearly a dead-end development. Indirect drives were added to overcome the limitation of the wheel size to something compatible with the rider’s leg size. But eventually it became clear that there were other methods of power transmission available that provided the same benefits without the cumbersome large diameter wheel, which had severe problems such as toppling the rider over the handlebars when it suddenly stopped — whether intentionally or accidentally.
1.6. Probably the first bicycle driven by means of a chain to the rear wheel Lawson’s 1873 safety bicycle.
Lawson had introduced the concept as early as 1873, be it without much initial response: a chain connecting the cranks with the rear wheel. Such an indirect drive system connecting the cranks with the driven wheel (which no longer had to be the same one that was steered) allowed an almost infinite ratio between crank speed and wheel speed. Consequently, without making the wheel particularly big, it was possible to achieve quite sensational traveling speeds, as long as the cyclist’s power was adequate and conditions were favorable.
Oddly enough, it took until 1885 before the concept of the chain-driven bicycle, as refined by John Kemp Starley on his Rover Safety Bicycle, from which our modern bicycle developed, began to catch on. The term safety bicycle referred to the use of small wheels, with the rider so far back that the risk of toppling over was minimized as compared to the conventional high-wheel bicycle. The term ordinary, often used to describe the high-wheel, dates from the period 1885 to 1890 — between the introduction of the safety bicycle and the ultimate decline of the high wheel.
Fig. 1.7. Starley safety cycle, approx. 1885.
Pneumatic Tires and Other Novelties
Although the American introduction of solid rubber tires around 1870 had provided a significant improvement over the original iron-hooped wooden wheels, and were standard on all high-wheels, the comfort of the safety bicycle was distinctly inferior to that on the high wheel. With the reduced wheel diameter, the shocks to which the road surface irregularities subjected the rider were much greater. This led to poor control over the bike, fatigue and other physical complaints such as headaches.
In 1887, the Irish veterinary surgeon John Boyd Dun lop, in trying to eliminate the cause of headaches of which his son complained after riding his small- wheeled tricycle, essentially reinvented the pneumatic tire (although a patent had been issued to an English inventor some twenty years before, it had never been applied and Dunlop was unaware of it). This development combined light weight with an effective suspension at the most suitable point, namely as close to the contact point between road and vehicle as possible. The pneumatic tire not only increased comfort, it also improved the bicycle’s overall efficiency on most road surfaces.
Fig. 1.8. Early high-tech drivetrain with shaft drive, dating back to 1885.
On a bike with solid tires, irregularities In the road surface were translated into vertical movement which was lost to forward motion. The pneumatic tire, by contrast, formed itself around the unevenness, absorbing much less of the propulsive force. Consequently, even bicycle racers, most of whom had disdainfully snubbed this comfort that contradicted their macho image of the sport, soon converted their bikes to pneumatic tires. By the end of the century, the pneumatic tire was used al most universally on quality bicycles.
The Modern Bicycle
1.9. Aerodynamic gadgets such as disk wheels are nothing new. These full and open disks were introduced as early as 1893.
During the last ten years of the 19th century and the first few years of the 20th, quite a number of other clever technical refinements were developed for the bicycle, ranging from low-resistance freewheels to effective braking systems, and from electric lighting to multiple speed gearing mechanisms. By and by, however, the industry’s interest in bicycle technology began to decline. That was due largely to the development of the motor car and the airplane, which soon attracted most of the engineers who had formerly worked on the development of the bicycle.
Even so, there remained to be a great demand for the bicycle at a time when it was the only form of individual transportation available to large numbers of people. Consequently, the first 20 years of the 20th century were by no means devoid of technical progress. What declined most dramatically was the newsworthiness of these developments. Instead of presenting the latest in bicycle technology, newspapers started to pay more attention to the pioneering feats associated with motoring and aviation.
Both these new industries — if that is the word to use for what remained a backyard operation for at least ten years, while the bicycle was being produced by modern industrial methods — owed much to the bicycle and the engineers who had perfected it. Many of the parts that went into the first planes and cars were borrowed from the bicycle, and the men who were responsible for their development had gained their knowledge in the field of bicycle engineering.
Renaissance of Bicycle Technology
It is interesting to observe that with the present renaissance of bicycle technology, the younger industries are beginning to repay their debt to the bicycle. Thus, quite a number of the new materials and construction techniques used on state-of-the-art bicycles were first developed for aerospace use. Similarly, the testing equipment used in other branches of industry are slowly finding acceptance in the bicycle field. The development of the HPV (human powered vehicle), as well as of some of the aerodynamic bicycle components used on more conventional racing bikes, would be impossible without the airfoil designs and materials derived from aerospace applications.
But there is much more to the renewed interest in bicycle technology which is largely centered in North America. Even though the industry seems to be more firmly than ever in the hands of a limited number of large, mainly Japanese, component manufacturers, who manage to dictate what will be fashionable in bike- tech matters, a surprising number of small American companies and individual designers are responsible for the real innovations, much of which is being absorbed by these large component makers.
There has been much progress in the last ten or fifteen years. Steel is slowly being supplanted by other materials for many purposes. We now have conventional tires that roll as lightly as the best tubular racing tires, brakes that require little force to stop reliably, and gears that predictably shift in defined steps. The same goes for the accessories: whereas a good luggage rack or light was virtually non-existent when I first started writing about the subject, there is now an abundance of good products in each of these areas.
1.10. Today’s version of the aero dynamic bicycle may look sleeker the principles behind it remain the same.
Special Bikes
Although the concept of the conventional bike is clear enough, there have been special machines ever since the bicycle was first developed. Von Drais already offered a tricycle, and in later times unusual machines of various types have often been available: tandems and trikes, recumbent bicycles and sociables (two-up bikes on which the riders sit side-by-side). From time to time, bicycles with fairings and completely enclosed machines, bikes with treadle drives and with shaft systems, indirectly driven ones and any number of oddities have been introduced.
1.11. The German Minister of Transportation inspecting a futuristic bicycle derivative at the biannual Cologne Inter national Bicycle and Motorcycle Show.
Recently, there is also a renewed interest in even more unusual machines, including the HPV’s that were mentioned above. These special designs are intended to prove how fast man can go on muscle power alone. Interesting though this is, it should not be forgotten that perhaps the main factor that makes the bicycle so fascinating is its practical application. Whereas other pieces of sports equipment are strictly limited in their use, the bicycle serves as a practical vehicle as well.
It is interesting and entertaining to observe the development of the torpedo-shaped HPV’s and other record machines, not to mention the flying bicycles with which such isolated feats as the crossing of the English Channel have been achieved. But even the most enthusiastic people involved in their development agree that they offer little in the way of practical applications for the bicycle as it is used today, or for the future of cycling. Prepare to see bikes that are very much like those of today for many years to come, even if the HPV and flying bike records continue to be broken on highly specialized machines.
Just the same, some impulses come from such developments and their pursuit should definitely be continued. For the time being, the application of such techniques and materials may well be limited to the field of pure racing, especially time trialing. No doubt we can expect to see some spin-offs from these innovations used on the normal bicycle some day — be these tires with less rolling resistance, wheels with reduced wind resistance, or hopefully more reliable components.
A development of an entirely different kind, namely the mountain bike, has already had a great impact on both the design of the bicycle and the way it is used. Who would have guessed in the early eighties that this would happen, in a time when mountain biking was purely a leisure activity for the adventurous thrill- seeker. Yet today the mountain bike not only accounts for the majority of adult bicycles sold in many countries, it is also greatly influencing the overall use of the bicycle.
1.12. High-tech frame by industrial designer Frans de la Haye, using a cross frame design arid tension wires. It never went into production.
The Scientific Bicycle
In the second half of the nineteenth century, the bicycle was taken seriously by the engineering and scientific community. It is fascinating to see that this interest is recurring. For scientific pursuits, the bicycle is more interesting than may seem obvious at first. Its apparent simplicity fools many into thinking there can’t be much to it. What makes the bicycle so interesting is perhaps the fact that one is always working at the mar gin: whereas in many other fields it is easy enough to add lots of power or weight, in bicycle matters, very marginal effects have to be considered at all times.
1.13. Mountain Bike adaptation of the tension wire cross frame by California mountain bike pioneer Joe Breeze.
To get just a few watts more power out of the rider is a significant achievement, saving mere grams of weight, decreasing air or rolling resistance by diminishingly small amounts, is often all that can be achieved, but is worthwhile in a sport where the limits are so clearly set by a fine-tuning of the balance between human performance, mechanical perfection and minimal weight.
Today’s development again does not only go into more refined mechanical gadgets, although these are the most obvious, featured prominently in the trade press. Much of the information that exercise physiologists have obtained about the human body is derived from the study of the bike as a machine and the role of the cyclist as its propulsive force. The bicycle ergometer and its more recent off-shoots are the devices used to measure human power, endurance, oxygen consumption, heart rate and efficiency, whether related to bicycle use or not.
Similarly, the scientific work done on developing the bicycle pays off in other disciplines as well. But the main benefit of the increased scientific interest in the bicycle is perhaps in the changed social status. Whereas it was considered at best a little odd to ride a bicycle twenty years ago, and that not only in the fully motorized USA, today it is quite accepted, even admired. It seems a bit of the aura of the renewed scientific interest in the bike is rubbing off to make the pursuit more glamorous than it had been for nearly a hundred years.
Bicycle Quality
Despite the renewed technical interest in the bicycle, there is still a lot of junk out there. Yet the vast majority of bikes and their components offered today are qualitatively superior to what has been sold for many years. This is due largely to the commendable shift of the bike buying public from cash-and-carry outlets and department stores to the qualified bicycle trade. In addition, the trade itself has greatly benefited from the rejuvenation that results from the entry of many experienced and knowledgeable cycling enthusiasts.
1.14. Today’s bicycle is the derivative of yesterday’s. Essentially, there is not much d between this turn-of-the century touring bike and most modern high-quality bicycles.
In the early bike boom of the nineteenth century, American-made bicycles were by and large of excellent quality, but so were English, Dutch, French, Italian and German machines. And all of them cost a lot of money: it was common for a working man to spend a month’s wages on a touring bike. Only with the in creased interest in motoring, did a period set in when bicycles were not considered worth spending much money on. Thus, by the nineteen-sixties, most bikes sold hardly represented a few days’ pay. Lately, how ever, the trend has been a return towards higher quality — and price.
Today the bicycle is no longer seen as a cheap item for those who can not afford a car. Instead the bicycle has become a status symbol in many circles. That is good for the sport and it is good for the industry — as it is ultimately to the cyclist. Numerous manufacturers have helped upgrade the image of the bicycle, some times employing dubious methods including the propagation of ideas that were later dropped again. Even so, the overall effect has been a positive one.
When considering this upgraded image and the high price tag attached to quality components, it should not be simply assumed that expense is always necessarily synonymous with quality and suitability. Although you usually pay for what you get, you don’t always get what you pay for, if only because the high price may be attributable to features that are irrelevant for your particular application. In this guide, you will encounter numerous suggestions to help you establish the quality and the suitability of a bicycle and its components for your specific circumstances — and detailed instructions on keeping a good bike working properly.
1.15. One reason for the high price of high-quality bicycles is the amount of work and detail that goes into making such a machine. Al though this is not your everyday bicycle, the exploded view of this Alex Moulton AM 7 shows the intricacy of its construction. Considering most of this is done by hand, the cost can be justified.