History of the Bicycle: 200 Years of Evolution

Introduction: the most efficient machine

The bicycle is often cited as the most energy-efficient means of transport humans have ever built. Over the same distance, it lets a person travel several times faster than walking with far less effort, and it needs neither fuel nor produces exhaust. Yet this seemingly simple machine took a surprisingly long process of trial and error to reach its present form. The wheel and the chain, the bearing and the pneumatic tire were each born in different eras at different hands, and the pieces only came together at the end of the 19th century.

In this chapter we trace the bicycle's journey in chronological order, from the dirt roads of Mannheim, Germany, in 1817 to today's public bike-share docks in Seoul. Rather than simply listing dates and inventors, we also look at why particular shapes appeared when they did. There was a clear engineering reason why the penny-farthing's front wheel grew as tall as a person, and the Tour de France had its own philosophy for banning derailleurs for so long. First skim the 200-year story, woven from technology and society, sport and industry, on the interactive timeline below; then we'll examine each part in detail in the text.

Leonardo da Vinci's bicycle? The sketch controversy

One drawing never fails to come up when people discuss the bicycle's origins. On the back of a page in the Codex Atlanticus, the collection of Leonardo da Vinci's notes, there is said to be a sketch strikingly similar to a modern bicycle, with a chain driving the rear wheel. The drawing reportedly came to light during manuscript restoration work at a monastery in the 1960s, and when the Italian scholar Augusto Marinoni published it in 1974, the claim that "the bicycle was already conceived in the Renaissance" spread around the world. An interpretation was even added that da Vinci's pupil Salaì had copied his master's idea.

Today, however, most researchers regard the sketch as a later forgery added to the page. The German historian of technology Hans-Erhard Lessing and others have pointed out that the drawing does not appear in photographs of the same page taken before the restoration, and that someone appears to have drawn the bicycle shape over a few circles and lines that were already there. Above all, the bicycle in the drawing features chain drive and a steerable front wheel, which would not appear for another 300 years, in far too finished a form. As we will see, the real history of the bicycle's invention was a long series of failures and incremental improvements, and a drawing that seems to skip that entire process only deepens the suspicion.

1817: Karl Drais's 'running machine'

On 12 June 1817, Karl von Drais, a forestry official and inventor in the Grand Duchy of Baden, Germany, wheeled a strange machine out into the streets of Mannheim. It consisted of two wooden wheels set in line, one behind the other, with a beam and a seat mounted on top. Sitting astride the seat and kicking off the ground with alternate feet, he is said to have ridden to a nearby coaching inn and back, a little over 13 km, in about an hour, a pace that held up well against the horse-drawn carriages of the day. Drais called the machine the Laufmaschine, or 'running machine'; in France it became the draisienne after its inventor, and in English the 'draisine'.

What made this device, with neither pedals nor chain, revolutionary was that it showed two wheels in line could stay upright. At a standstill the design inevitably topples, but once moving above a certain speed the rider can keep balance by turning the front wheel slightly. This is exactly the principle behind today's pedal-less 'balance bikes' on which children learn to ride. Drais fitted a handle to steer the front wheel and even added a rest to support the arms. The machine is estimated to have weighed around 20 kg.

Mount Tambora and the 'Year Without a Summer'

What's intriguing is the historical backdrop to the draisine's appearance. In April 1815, Mount Tambora on the island of Sumbawa, in present-day Indonesia, produced the largest eruption in recorded history. Ash and sulfate aerosols blasted into the stratosphere blocked out sunlight, and the following year, 1816, Europe and North America endured the 'Year Without a Summer'. Snow fell in June, grain failed to ripen, and crop failures and famine followed; as the price of oats soared, feeding horses became difficult. With more horses starving or being slaughtered, interest grew in a means of transport that could replace them.

Some historians see this climate disaster as the direct trigger that led Drais to conceive a 'machine that runs without a horse'. Since Drais had been working on human-powered vehicles before then, it's hard to claim the volcano was the sole cause. Still, the argument that the social problem of a horse shortage provided fertile ground for the invention to attract attention is persuasive. The draisine was briefly fashionable across Europe, but riders avoiding rutted roads by using the sidewalks kept colliding with pedestrians, several cities banned them, and the craze cooled within a few years.

The 1860s: pedals arrive, and the 'boneshaker'

For about 40 years after the draisine, two-wheelers faded into the background of history. They returned to the stage in Paris in the 1860s. The workshop of Pierre Michaux, a maker of carriage parts, and his son Ernest began producing the vélocipède, with cranks and pedals attached directly to the front axle. At last, riders could keep moving with their feet off the ground. Around the same time, the French-born mechanic Pierre Lallement received a US patent for a pedal drive in 1866, and opinions still differ over who came up with the pedal first.

Michaux's velocipede became hugely popular from around the 1867 Paris Exposition, and in 1868–1869 'velocipede mania' swept France, Britain and the United States. This was also when riding schools opened in converted indoor riding halls and the first official races were held. But the machine was anything but comfortable. A heavy wrought-iron frame, wooden wheels and the iron bands around them transmitted every jolt of the cobbled streets straight into the rider's body. English speakers nicknamed it the boneshaker. It often weighed well over 30 kg.

When the Franco-Prussian War broke out in 1870, the French bicycle industry took a heavy blow, and leadership passed to Coventry in England, where the sewing-machine and precision-engineering industries were well developed. This historical backdrop explains why much of the innovation in bicycle technology over the following decades took place in Britain.

The 1870s: the high-wheeler and the 'penny-farthing'

The boneshaker had a fundamental limitation. Because the pedals were attached directly to the front axle, one turn of the pedals turned the front wheel exactly once. There's a limit to how fast a person can comfortably pedal, so the only way to go faster was to increase the distance covered per revolution, in other words the wheel's diameter. A 1 m wheel travels about 3.1 m per revolution, while a 1.5 m wheel travels about 4.7 m. With the same pedaling, that's 50% more speed.

So front wheels grew bigger and bigger, until it became standard practice to choose the largest wheel the rider's leg length would allow. Racing front wheels sometimes exceeded 1.5 m in diameter. The 'Ariel', introduced in 1870 by James Starley and William Hillman in England, used a tension wheel held in place by thin wire spokes and a hollow steel-tube frame, making the huge front wheel light and strong. At the time, the high-wheel bicycle born this way was called the ordinary, meaning simply 'a normal bicycle'. The name 'penny-farthing', from its resemblance to a large penny coin beside a small farthing, is said to have come into wide use toward the end of the 19th century, as the design was becoming outdated.

The high-wheeler was fast and elegant. In 1882, Herbert Cortis of England became the first to ride more than 20 miles (about 32 km) in an hour on a high-wheeler, and from 1884 to 1886 Thomas Stevens rode one around the world. But the price was high. Because the rider sat almost directly above the front wheel, 1.5 m off the ground, a single stone could pitch them forward headfirst, and such crashes were common. English speakers called this taking a 'header'. Even getting on and off took skill, so the high-wheeler remained the preserve of brave, athletic young men.

1885: the Starley Rover and the 'safety bicycle'

Attempts to solve the high-wheeler's dangers came from many directions. The answer that changed history was the chain. Instead of connecting the pedals directly to the wheel, linking a large sprocket on the crank axle (the chainring) to a small sprocket on the rear wheel with a chain lets one turn of the pedals rotate the rear wheel two or three times. Speed could now come from the ratio of tooth counts, the gear ratio, rather than from a bigger wheel. In England, Harry Lawson had already introduced the 'Bicyclette', with chain drive to the rear wheel, around 1879, but it was not a major commercial success.

The decisive blow came from John Kemp Starley, nephew of James Starley, who had built the 'Ariel' high-wheeler. The Rover he unveiled in Coventry in 1885 had front and rear wheels of similar size, a saddle set low between them, and chain drive to the rear wheel. Riders could easily put a foot down, and the low center of gravity all but eliminated the fear of pitching forward. People called this new type the safety bicycle to distinguish it from the high-wheeler. Over the next few years the Rover was refined again and again, gaining a raked front fork for steering stability and converging on the diamond frame made of two triangles.

Remarkably, this layout remains almost unchanged 140 years later. The great majority of road bikes, hybrids and mountain bikes sold today still follow the Rover's basic design: a frame of two triangles, two wheels of similar size, and chain drive to the rear wheel. Materials and components have changed endlessly, but the bicycle's 'skeleton' was essentially complete by the late 1880s. Incidentally, the company bearing the Rover name later turned to cars and became one of Britain's best-known automotive brands.

1888: Dunlop's pneumatic tire

Even after the safety bicycle appeared, one problem remained. Its smaller wheels took harder knocks from the road than a high-wheeler's, and the solid rubber tires of the day absorbed almost none of the shock. The man who solved it was, surprisingly, not from the bicycle trade at all but a veterinarian in Belfast, Northern Ireland: John Boyd Dunlop. When his young son complained of headaches from the jolting of his tricycle, Dunlop devised a way to wrap the wheel with an air-filled rubber tube, and he was granted a patent in 1888.

In fact, the idea of the pneumatic tire had already been patented by the Scot Robert William Thomson in the 1840s. But there was no vehicle to use it on at the time, and the idea was forgotten. Dunlop's tire, by contrast, arrived just as the bike boom took off. When bicycles on pneumatic tires crushed their solid-tired rivals in races in 1889, the mood in the industry changed overnight. In 1891, the Michelin brothers in France introduced a detachable design that let the tire be removed from the rim to make puncture repair easy. Offering comfort, speed and easy repair, the pneumatic tire was the last piece of the puzzle that completed the safety bicycle, and before long it became a foundation of the automobile industry as well.

The 1890s bike boom and women's emancipation

Once the chain-driven safety frame met the pneumatic tire, the bicycle was no longer a dangerous toy for daring young men. The 1890s saw an unprecedented bike boom in Europe and America. Factories raced to adopt mass-production methods, and prices fell rapidly. Cycling clubs led the 'Good Roads Movement' demanding better roads, and the paved roads it produced became the roads cars would drive on a few years later. The fact that the Wright brothers ran a bicycle shop before building their airplane, and that car companies such as Peugeot, Opel and Rover started out as bicycle makers, shows that the bicycle was the training school of modern mechanical industry.

The most dramatic change, though, came in women's lives. Middle-class women of the time were bound by corsets and floor-length skirts, and traveling far without a chaperone was socially taboo. The bicycle gave women, for the first time, the freedom to go wherever they wanted, whenever they wanted. To ride, women began wearing loose trousers gathered below the knee, known as bloomers. Named after the American women's rights activist Amelia Bloomer, who championed them in the 1850s, the garment was at first an object of ridicule, but with the bike boom it became a symbol of the 'rational dress' movement.

"Let me tell you what I think of bicycling. I think it has done more to emancipate women than anything else in the world. It gives women a feeling of freedom and self-reliance. I stand and rejoice every time I see a woman ride by on a wheel." — Susan B. Anthony, interview with Nellie Bly, 1896 (New York World)

These words from Susan B. Anthony, a leader of the women's suffrage movement, are the most famous testimony to the bicycle as more than a vehicle: a tool of social change. In 1894, a woman known as Annie Londonderry set off to cycle around the world, and the temperance campaigner Frances Willard published a book about learning to ride in her fifties, inspiring other women. There was no shortage, of course, of voices condemning women cyclists as 'unladylike', or of baseless medical warnings that cycling harmed women's health. But the procession of women on pedals did not stop, and it fed into the broader expansion of women's suffrage in the 20th century.

A history of gearing: from flipping wheels to Campagnolo

When the safety bicycle adopted the chain, the concept of a 'gear ratio' was born, but early bicycles were single-speeds with just one ratio. Everyone knew that climbing called for an easy gear and flat roads for a hard one, but building a device to change gear on the move was no easy task. Early 20th-century racers fitted a different-sized cog on each side of the rear wheel; at the foot of a climb they would stop and flip the wheel around to change gear.

From the early 1900s, the French cycle tourist Paul de Vivie (pen name Vélocio) campaigned hard for multi-speed gearing. Henri Desgrange, founder of the Tour de France, on the other hand, believed gears undermined a pure contest of riders' strength and long refused to allow them in the race; he is said to have remarked, in effect, that "variable gears are only for people over 45." The Tour de France did not officially permit derailleurs until 1937.

The most iconic name in the history of gearing is Italy's Tullio Campagnolo. As the story goes, while racing as an amateur in a cold mountain race in the late 1920s, he was unable to undo his wheel's wing nuts with frozen hands, couldn't change gear, and lost the race. Starting from that experience, he devised the quick release, which fastens and releases the wheel with a single lever, patented it around 1930, and then turned to developing derailleurs. After the rod-operated shifters of the 1940s, the Gran Sport he unveiled around 1949 used a cable to move a parallelogram linkage that shifted the chain onto the neighboring cog, and this principle survives in most derailleurs to this day. In the same period, France's Simplex and Huret, and later Japan's SunTour and Shimano, also made major contributions to derailleur innovation. In particular, the 'slant parallelogram' design devised by SunTour in the 1960s is regarded as an invention that greatly improved shifting precision.

1903: the birth of the Tour de France

As cycling went mainstream, bike racing soon became a huge spectacle. Its pinnacle is the Tour de France. In 1903, the French sports newspaper L'Auto planned an unprecedented long-distance race around France to win its circulation war with a rival paper. The first edition ran over six stages totaling about 2,428 km, setting out from Paris and returning via Lyon, Marseille, Toulouse, Bordeaux and Nantes. Some stages exceeded 400 km and had to be ridden through the night, and riders had to fix breakdowns themselves without mechanical help. The first winner was Maurice Garin, said to have been a former chimney sweep.

The race was a huge success. Newspaper sales soared, and the Tour, held every year except in wartime, established itself as the world's most prestigious bike race. The yellow jersey (maillot jaune) worn by the overall leader was introduced in 1919; the widely told explanation is that it came from the yellow paper L'Auto was printed on. The Tour de France has been more than a sporting event; it has also served as a proving ground for bicycle technology. Almost every innovation in today's bikes, from derailleurs, lightweight materials and clipless pedals to aero design and electronic shifting, was tested or fought over on this stage.

Cycling history in Korea

The bicycle is believed to have first arrived in Korea at the end of the 19th century. Records and anecdotes tell of reform-era figures such as Seo Jae-pil and Yun Chi-ho riding bicycles around the 1890s, when it was called jajeoncha (自轉車), meaning 'self-turning cart', or jahaenggeo (自行車). At first it was a curiosity for a tiny elite and for foreigners, but in the early 20th century it gradually spread to practical uses such as mail and shop deliveries.

Eom Bok-dong, the cycling hero of colonial Korea

For Koreans under Japanese colonial rule, the bicycle carried a special meaning, and at its heart was Eom Bok-dong (1892–1951). A clerk at a bicycle shop, he made his name by beating Japanese riders to win a bicycle race held in Gyeongseong (now Seoul) in 1913, and he is said to have gone on to success in many more races. At a time of pent-up resentment toward Japan, the mere fact of a Korean beating Japanese riders was a great comfort, and he rose to become a national hero, so much so that a popular lyric ran, 'Look up and see An Chang-nam; look down and see Eom Bok-dong.' Records also show, however, that later in life he was implicated in bicycle thefts, so today many people try to see both his heroic side and his human failings.

The Samchuly and the first Korean-made bicycles

The starting point of Korea's post-liberation bicycle industry was Kyungsung Precision Industry, founded by Kim Cheol-ho in 1944. This maker of bicycle parts changed its name to Kia Industrial in 1952 and in the same year produced the first bicycle made in Korea, the 'Samchuly'. Born amid the ruins of war, the Samchuly became a symbol of Korea's homegrown machine industry. Kia Industrial later grew into a car company, while the bicycle business was spun off as a separate company in 1979 and continues today as Samchuly Bicycle. In the 1960s and 1970s, bicycles carried the everyday life of the industrialization era as the cargo bikes of rice shops, postmen and newspaper carriers.

The age of leisure, and Ttareungyi

Since the 2000s, the bicycle in Korea has shifted from a means of earning a living to a symbol of leisure, health and green transport. Bike paths were built along rivers, and in 2012 the roughly 633 km cross-country cycle route from the Ara West Sea Lock in Incheon to the Nakdong River Estuary Bank in Busan opened, becoming a bucket-list ride for many enthusiasts. In 2015, Seoul's public bike-share 'Ttareungyi' officially launched. Rented by smartphone and returnable at any station, Ttareungyi quickly became a staple of city life and is now widely used for the 'last kilometer' between subway and bus. In 2018, a new chapter opened when the law was changed to let pedal-assist e-bikes that meet certain standards use bike paths.

The 1970s: the birth of BMX and the mountain bike

By the mid-20th century, with the car now king of transport, the bicycle in America was regarded mainly as a children's toy. Yet it was those very children and young people who opened a new chapter in cycling history. From the late 1960s, kids in Southern California began imitating motocross riders, racing small-wheeled bikes over dirt hills and jumps. When the opening of the 1971 motorcycle documentary On Any Sunday showed kids riding bikes on dirt, the pastime became a nationwide craze and established itself as a sport in its own right: BMX (Bicycle Motocross). BMX racing became an Olympic event from the 2008 Beijing Games.

Around the same time, another experiment was under way in Marin County, north of San Francisco. Young riders picked up sturdy, heavy secondhand cruisers built in the 1930s and '40s and modified them with fat tires and motorcycle levers. People called these junkers 'clunkers'. From 1976, they held races for the fastest descent down a steep dirt fire road on Mount Tamalpais. Because riders dragged their coaster brakes all the way down, the grease inside the hub burned off and had to be repacked after every run, which gave the event its name: the Repack race.

Several Repack racers soon became figures who would transform the bicycle industry. Frame builder Joe Breeze is credited with creating the first modern mountain bike when, around 1977, he built a new frame designed from scratch for off-road riding, the so-called 'Breezer'. Gary Fisher, reputed to hold the fastest Repack time, founded a company called MountainBikes with Charlie Kelly in 1979 and sold bikes built on Tom Ritchey's frames. When Specialized launched the first mass-produced mountain bike, the Stumpjumper, in 1981, MTB spread explosively, leading to the first UCI World Championships in 1990 and Olympic status at the 1996 Atlanta Games. Many technologies first tried on mountain bikes, such as suspension, disc brakes and wide gear ranges, later spread to other bikes.

The materials revolution: steel → aluminum → carbon → titanium

The history of frame materials has been an endless contest over how light, how stiff and how durable a frame can be. From the late 19th century to the late 20th, the undisputed star was steel. Butted chromoly tubing, thick at the ends and thin in the middle, like the '531' tubing Reynolds of England introduced in 1935, was the standard for racing bikes for decades thanks to its light, lively ride. Steel is tough and easy to repair, and it remains popular for touring bikes and handmade frames.

In the 1970s and '80s, aluminum threw down the challenge. Aluminum has only about a third of steel's density, but it is also less stiff, so tubes of the same diameter flex too much. Companies such as America's Cannondale solved this with 'oversized' tubes of much larger diameter, and aluminum frames went mainstream in the 1990s. Light and affordable, aluminum is still the main material for entry-level bikes.

The real revolution was carbon-fiber-reinforced plastic (carbon). Made by setting carbon fibers in resin, carbon has the unique advantage that, by adjusting the direction and number of fiber layers, designers can make some areas stiff and others compliant exactly where they want. Carbon frames attracted attention when they won Grand Tours in the mid-1980s, and as one-piece (monocoque) molding advanced in the 1990s, professional racing became essentially carbon's domain from the 2000s onward. Bikes became so light that the UCI went as far as setting a minimum weight of 6.8 kg for race bikes. Titanium, meanwhile, was tried from the 1970s and came into serious use in the 1980s and '90s. Rustproof, fatigue-resistant and known for its distinctively smooth ride, it is called a 'frame for life', but it is difficult to work and therefore expensive.

1984: indexed shifting (SIS) and clipless pedals

For decades after Campagnolo, shifting was 'friction' shifting. The derailleur moved exactly as far as you pulled the lever, so you had to fine-tune the lever position by ear until the chain settled precisely on the next cog. That was no problem for experienced riders, but it was hard for beginners, and even experts often fumbled while stamping on the pedals up a climb.

In 1984, Japan's Shimano introduced SIS (Shimano Index System) on its Dura-Ace groupset. Notches in the lever made it 'click' into place one step at a time, and the cable, derailleur and sprockets were designed together as a single system to match. Indexed shifting, where moving the lever one click moves the chain exactly one cog, soon became the industry standard. In 1990 came STI, combining brake and shift levers in one so riders could shift without taking their hands off the bar, and Campagnolo answered with 'Ergopower' in the early 1990s.

In the same year, 1984, the French ski-equipment company LOOK unveiled the clipless pedal, adapting the principle of the ski binding. Until then, racers fixed their feet with toe clips and leather straps on the pedals, slotting a groove in the shoe sole onto the pedal; with the straps cinched tight, getting a foot out in a crash was difficult. LOOK's pedal let the cleat on the shoe sole 'click' into the pedal and released easily with an outward twist of the heel. When Bernard Hinault won the 1985 Tour de France on these pedals, clipless pedals spread almost overnight. The name 'clipless' comes from the absence of toe clips. In 1990, Shimano launched its walkable SPD pedals for mountain biking.

Electronic shifting: Di2 and eTap

Even after indexed shifting, cable-operated shifting had chronic problems. Cables stretch over time, and dirt and rust in the housing make shifting sluggish. Mavic and others tried electronic shifting in the 1990s, but issues with batteries, waterproofing and reliability kept it from catching on. What changed things was Shimano's Dura-Ace Di2, released in 2009. Pressing a button on the lever sends an electrical signal down a wire to a small motor inside the derailleur, which moves the chain to precisely the right position. No cable tension adjustment is needed, and shifts stay as precise after thousands of changes as on day one.

In 2015, America's SRAM went a step further, announcing Red eTap, which connected levers and derailleurs wirelessly with no wires at all. Campagnolo also introduced an electronic system called EPS in the early 2010s. At first reserved for top-end racing components, electronic shifting gradually trickled down to mid-range groupsets, and today it's routine to remap shift buttons or check battery levels in an app.

Disc brakes and tubeless tires

For a long time, the mainstream bicycle brake was the rim brake, which grips the wheel's rim with rubber pads. It's simple and light, but braking power drops sharply in the rain, and the rim can overheat on long descents. Disc brakes, first established on mountain bikes in the 1990s, use a caliper to grip a separate metal disc (the rotor) mounted at the wheel's center, delivering consistent braking regardless of the weather. Hydraulic discs in particular offer strong, finely modulated braking with little effort.

Road bikes were slower to adopt them because of the added weight and safety concerns about sharp rotors. After a trial period from 2015, the UCI fully permitted disc brakes in professional road racing from the 2018 season, and within just a few years most pro teams and new road bikes had switched to discs. Disc brakes also had a side effect: freed from the clearance limits of rim brakes, frames could accept wider tires.

Tubeless tires are part of the same trend. Their real starting point was the UST standard for mountain bikes launched in 1999 by Mavic, Michelin and Hutchinson: like a car tire, the tire and rim seal the air directly, with no inner tube. Sealant inside plugs small holes on its own, and 'snakebite' punctures, where the tube is pinched against the rim, disappear. Because they can be ridden at lower pressures for better grip and comfort, tubeless tires are now effectively standard on mountain bikes and have spread rapidly to road and gravel bikes. The overturning of the old wisdom that 'narrower and harder is faster', and the acceptance of research showing that reasonably wide tires can be faster on real roads, have also come about in the past 20 years.

The e-bike era

The idea of a bicycle with an electric motor is older than you might think. Records show that in 1895 Ogden Bolton Jr. of the United States was granted a patent for an electric bicycle with a motor in the rear hub. But with heavy, low-capacity lead-acid batteries, a practical product was hard to build. The turning point was Yamaha's PAS (Power Assist System), launched in Japan in 1993. Rather than simply running the motor with a throttle, it used a sensor to detect pedaling force and added motor power in proportion: 'pedal assist'. When the rider stops pedaling, the motor stops too, so it preserves the essence of the bicycle while easing only the burden of climbs and headwinds.

From the 2000s, light, high-capacity lithium-ion batteries became widespread, and around 2010 mid-drive systems with the motor at the crank axle took off, driving explosive growth in the e-bike market. The European Union shaped the market by treating pedal-assist bikes with a rated motor output of 250 W and assistance up to 25 km/h in the same category as ordinary bicycles. In Korea too, since March 2018, pedal-assist e-bikes whose motor cuts out at 25 km/h and which weigh less than 30 kg in total have been allowed on bike paths. Today e-bikes come in many forms, from city bikes for commuting to cargo bikes for hauling and e-MTBs for climbing rough terrain. Their workings and the regulations are covered in detail in the 06 E-bikes chapter.

The future of the bicycle

Over 200 years the bicycle has changed remarkably, and yet it has also remained remarkably the same. The principle of turning leg power into the rotation of two wheels, and the skeleton of diamond frame and chain, have not strayed far from the 1885 Rover. Future change, too, will most likely add new layers on top of that skeleton rather than abandon it.

Several trends already offer a glimpse of the near future. E-bikes are gaining anti-lock braking (ABS), automatic shifting and theft tracking, and there are growing attempts to 3D-print custom titanium and carbon parts for individual riders. Airless tires that never need inflating, tail lights that use radar to warn of vehicles approaching from behind, and smart helmets that detect a crash and call for help have all reached the market. At the city level, more and more cities are expanding protected bike lanes and public bike-share systems to pursue carbon neutrality and ease congestion.

Ultimately, the future of the bicycle depends as much on how cities and societies embrace it as on technology. Just as the bicycle of the 1890s brought freedom to women and pavement to roads, the bicycle of the 21st century can be one answer to the questions of the climate crisis, health and the reshaping of urban space. It's quite meaningful that this machine, born in an era when a volcanic eruption made horses scarce, is once again in the spotlight in an era searching for ways to travel beyond fossil fuels. In the next chapter, we'll look one by one at the many kinds of bicycle this long evolution has produced.

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