Development (bicycle)

The development of a Bicyclette is the distance covered by this one at the time of a turn of pedals.

Braquet and development should not be confused. Indeed, the gear ratio is the combination between the number of teeth on the plate and the number of teeth on the pinion. The gear ratio induces a development, by taking of account the size of the driving wheel (back).

A thus induced gear ratio only one development. However, the same development perhaps obtained by various different gear ratios.

In a total way:

more the gear ratio is high, plus the development is large:

more the plate is large, plus the development is high;
more the pinion is small, plus the development is high;

more the aft wheel is large, plus the development is high.

Let us note that there exist systems of reduction inside the hub postpones, the gear ratio thus does not depend only on the size on the plates and pinion. With regard to the result:

a significant development makes it possible to advance quickly but requires main efforts; a significant development is used when the limiting factor is the speed of pédalage;
a weak development makes it possible to assemble important slopes; a weak development is used when the limiting factor is the muscular power.

Calculation

If the Diamètre of the aft wheel is D , then its Périmètre is p = π× D . With each turn of wheel, the bicycle thus advances length p .

; Note

One indicates the diameter of the rim in general; it is necessary, in any rigor, to add the thickness of the tire.

In addition, attention with conversions of unit: the advance of the bicycle is expressed in Mètre, the diameter is given in general in Millimètre (a “wheel of 700” has a diameter of 700 mm, that is to say 0,7 m) and sometimes in inches (a wheel of “24 inches” has a diameter of 0,6 m). The ideal is all to express in meter.

With each turn of pedal, the wheel makes a number N turns given by the gear ratio, the bicycle thus advances N × p meters. The more the gear ratio is raised and the more quickly the cyclist advances for a constant speed of pedals.

If the gear ratio is equal to 1 (for example 32×32), a turn of pedals is equivalent to a turn of wheel. The cyclist then advances circumference of the wheel to each turn of pedals, that is to say, for a wheel of 700 mm (0,7 m), a development of 2,2 Mr.

Regulation

In many countries, the cycle races are regulated on the level of the developments, for the youngest runners.

It is very easy to control the development of a bicycle. It is enough to trace two lines parallel, on the ground, distant of the development to be respected. The bicycle is placed on a line and one carries out a turn of pedals. If the bicycle does not exceed the other line, the development is correct.

Regulation of FC, valid in 2006

the tiny ones (boys): from 13 to 14 years in the year, the authorized maximum development is of 6,14 m

the juniors (boys): from 15 to 16 years in the year, the authorized maximum development is of 6,67 m

the tiny ones and juniors (girls): the authorized maximum development is of 6,67 m

the juniors (1st year): from 17 to 18 years in the year: the authorized maximum development is of 7,93 m

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