In 1903 the Tour de France was born. The first winner of this great event is Maurice Garin.
After the First World War, the term “bicycle” became the popular word to describe the bicycle used by workers, peasants and children8.
In the 1930s, multi-speed systems began to be used in cycling competitions.
The vélocar appears in the 1930s, recumbent bicycle and ancestor of the velomobile.
During the occupation of France by Germany, cars were restricted to the use of doctors, the police or the militia, the bicycle becoming the queen of transport (supplies and the black market, trips to work or to go seeing relatives, development of bicycle taxis in large cities), success in cycling competitions17.
Derailleurs developed during the 1950s.
Finally, velomobiles were reborn at the end of the 1980s.
Since the beginning of the 1990s, in several countries, spontaneous demonstrations have brought together, once a month in several hundred towns, defenders and promoters of the use of cycling in towns. These are the critical masses or velorution in France.
On March 28, 2017, in a public note18, the think tank La fabrique écologique estimates that the Interministerial Coordination for the Development of the Use of Cycling (Ciduv) is "endowed with low human and budgetary resources" and "cannot ensure the steering of an ambitious national strategy ”. France lacks understanding of the brakes on cycling. The bicycle kilometer allowance (IKV) is struggling to develop and the Ademe devotes few resources to cycling. Responsibility for cycling is delegated at the local level (by the NOTRe law) to communities where the “public transport” culture dominates, lacking a “strong national impetus”. The think tank proposes the bases for a national bicycle strategy in order to make up for the 20–25 years of delay acquired in Northern Europe, advocating the creation of an interministerial bicycle mission (MIV) and the consideration of the bicycle no longer as a a leisure activity but as an “instrument of transport policy” 19.
In fact, in France, according to an INSEE study for 2015, only 2% of working people go to work by bicycle. The bicycle is mainly used when the workplace is up to 4 km from home. This mode of transport is generally much less used than the automobile, which is largely predominant, public transport or walking, but it is on a par with motorized two-wheelers20. In the city, however, as in Paris, bicycle trips represent a third of those made by car21
The bicycle has only two points of support on the ground: it is necessarily in unstable equilibrium. Physicists speak of a metastable equilibrium because the passage from the position of temporary equilibrium to a position of perceptible imbalance is relatively slow.
The main forces in action are:
gravity, which tends to pull the bike towards the ground;
centrifugal force, which when the bike turns, tends to straighten it out of the turn.
The balance is maintained dynamically by the actions of the rider, who always endeavors to straighten his machine by tilting it slightly in the direction opposite to that in which it begins to fall.
The cyclist therefore constantly juggles between these two forces to compensate for the effects of one with the other. It is helped in this by the trail of the bicycle: it is the distance between the intersection of the axis of the fork with the ground and the point of contact of the front wheel with the ground. Indeed, the axis of the fork is inclined so that its intersection with the ground is in front of the point of contact of the wheel with the ground. Thus, if the bicycle is tilted to one side, the front wheel is forced to position so as to rotate the bicycle on the same side, thereby initiating a turn tending to balance that tilt.
Finally, when the bicycle is rolling, the gyroscopic effect linked to the rotation of the wheels thwarts any variation in the position of their axes. This phenomenon is proportional to the speed of rotation of the wheels and to their mass. This effect is usually negligible and is normally imperceptible to the cyclist. Indeed, the mass and therefore the inertia of the bicycle and its rider are an order of magnitude greater than that of the wheels, which considerably reduces the influence of the gyroscopic effect.
The frame is the main part, it usually consists of a triangle on which the rider's weight is distributed from the fulcrum of the saddle, associated with a second smaller triangle on which the rear wheel is mounted: this second triangle is made up of shrouds (outer edge of the rear triangle) and chainstays (base of the rear triangle). The front wheel is fixed to the frame by a fork, the upper part of it is mounted on ball bearings through an almost vertical tube at the front of the frame. These ball bearings constitute the headset. The top of the fork forms a stem to which the handlebars are attached. The fork can be suspended. Many modern bicycle models are also designed without fixed seatstays, replaced by a suspended system. This system can take various and varied forms, from the use of joints based on bearings, to the use of flexible materials (titanium in particular) which allow progressive deformation. Such "full suspension" bikes are designed for riding on uneven terrain such as mountain biking to provide additional comfort.
The energy is supplied by the cyclist through his feet, with which he presses on the pedals, connected to one or more gears at the level of the crankset: the chainring (s). The rear gear, the pinion (but there are often several pinions of different sizes attached together, this is called a cassette) is mounted on the rear wheel by a non-return ratchet mechanism: the freewheel. The transmission of movement between a chainring and a pinion is provided by the chain. Depending on the type of practice for which the bike is designed, the cassette can be "flat" as often on a road bike, which means that between two successive sprockets, there is only one more tooth. on the largest; on other types of bikes such as mountain bikes, the number of teeth can increase much faster between successive sprockets. The set of elements included between the pedals and the rear wheel is referred to by the term transmission.
One of the most important parts of a bicycle is the braking system. It is made up of two independent brake handles, each controlling a jaw which applies rubber buffers to the rim via brake cables. The cables are mostly protected in sheaths. Certain braking systems, for more performance, are based on the principle of the disc brake, or the drum brake, integrated into the hub.
Since the 1950s, most brake systems have been derived from the side-pull shoe design invented by Campagnolo. The two arms of the jaw tighten when the cable, attached to the end of one of the arms and passing through the end of the other, is stretched. The pressure of the pads applied by the rim is balanced thanks to a spring which distributes the force between the two jaw arms.
The increasingly frequent use of larger tires on mountain bikes ended up posing a problem: the rim and its tire became too wide to fit between the brake shoes. Initially, the cantilever system provided an answer to this problem. The jaw arms became independent, while being connected by a short braking force distribution cable. The control cable is then fixed in the middle of the distribution cable. However, this system has some weaknesses: if the fixing of the control cable is not centered, the force is poorly distributed between the arms, and if the connector becomes unhooked, the distribution cable can block the wheel suddenly by getting stuck in tire designs, which can lead to an accident if it happens on the front wheel.
A more suitable solution to the problem of tire width is the v-brake. The cable is fixed in such a way that it is directed upwards so that it cannot fall back on the tire, and also transmits the braking power delivered by the brake lever much better, while being a little easier to handle. center during assembly.
Tires and rims
The wheels are fitted with pneumatic tires, or tires, in order to increase the comfort of the cyclist, and to reduce the stresses undergone by the mechanics.
The tires can be attached to the rims in two ways: either glued (we speak of tubulars), or mounted on a notch which goes around each side of the rim (conventional tires). The width and the tread patterns of the tires are adapted according to the use of the bike: thin and smooth for the road, thicker and with numerous studs for mountain biking, etc.
In North America and other areas where the ground freezes during winter, it is possible to install tires with metal spikes. These provide greater grip on icy surfaces and enthusiasts of this means of transport can thus circulate throughout the winter.
Signaling equipment is mainly composed of active lighting and reflectors or reflectors.
The lighting consists of a white lamp towards the front, a red one towards the rear, most often supplied by an alternator, often incorrectly called a "dynamo".
Reflectors intended to supplement the visibility of the cyclist can be installed. For lateral visibility, these may be orange reflectors which are fixed between the spokes of the wheels, or white reflective strips painted on the tires or inserted between the spokes right up against the rim. For visibility from the front and from the rear, the sidelamps are normally lined with reflectors of the same color and the pedals are fitted with orange reflectors.
Finally, bicycles generally have a bell activated on the handlebars, which clearly distinguishes them from motor vehicle warning devices.
The mandatory systems in France are listed on the website of the French Ministry of the Interior28