Rainer Pivit and Falk Rieß

The Bicycle - The Poor Man's Motor Car?

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Excerpt from: Bicycle Reference Manual for Developing Countries. Edited by Barbara Gruehl Kipke, April 1991.

The simplest and traditional means of transport is the human head. Loads are carried on it which the carrier cannot Lift up himself, weighing 35 kg to 40 kg. These are then carried over a period of several hours to the local market for example. Technical devices which have been adapted to avoid this strenuous work Include special frames, which make carrying easier, carts drawn by animals, and bicycles equipped with special devices for transporting loads.

This applies to the transport of loads in rural areas, and the same can be said of the transport of passengers in the towns. Where there is no local transport system operating on the basis of a public mass means of transport, and this is the case in almost all developing countries, the bicycle is a cheap, simple and quite fast means of transport, provided that the area is geographically suitable for bicycles with no steep hills.

Looking at the statistics for the number of bicycles and the production figures for bicycles in quite different countries it is noticeable that the number of bicycles is at its highest in the industrialized countries, where relatively few people ride bicycles and most people drive motor cars. It is also apparent that most developing countries (at least in Africa) are forced to import bicycles, as they do not have any bicycle factories of their own. The bicycle factory in Dar es Salaam, Tanzania, for example, which was opened in 1978, can only produce 60% of the components required. It is also noticeable that there are just as many motor cars as bicycles in the world, and that the rate of growth in bicycle production in the developing countries is very high, while production in the industrialized countries is stagnating.

If one looks at the prices of bicycles in developing countries, it is apparent that, although the prices appear to be very low, the bicycle is a valuable article, which only people who have managed to save some money can afford to buy. In 1975 a bicycle in India cost between $ 24 and $ 35, while the average annual per capita income was only $ 100, that is three times as much. Tricycles, or rickshaws, which are used to earn a living, cost between $ 100 and $ 200, which means that the majority of rickshaws do not belong to their drivers, but instead are rented out. In Tanzania the situation is similar. In 1978 the Swala bicycle, which is manufactured there, cost 23 pounds, while the annual per capita income amounted to 75 pounds.

While most bicycles, as already mentioned, are made in large factories or abroad, in Asia the rickshaw, or the transport tricycle, is usually manufactured by small or medium-sized firms and workshops, which buy standard parts from the large firms and make all kinds of special models to suit different purposes. In addition to this, bicycles guarantee the existence of a large source of employment, the mobile cycle workshops, which owe their existence to the fact that the majority of cyclists are unable to service their vehicles themselves and are dependent on the services of a repair shop.

The bicycles which are made in China and India, and which are to be found in a similar form in many developing countries, are the equivalent of man's roadster bicycle, like the ones manufactured in England after about 1905. Apart from minor changes in the material of the frame, in the paint, chroming and to the saddle practically no changes have been made: wheels and tyres 28 x 1 1/2'', stirrup brakes, Westwood rims, free-wheel coaster-hub without brake, development approx. 5.5 m (i.e. the distance travelled per crank revolution), heavy weight of over 20 kg. It is worthy of note that due to the design of the frame (diamond-frame with horizontal top tube) it is impossible for the majority of women in the Third World to ride a bicycle, unless they disregard the conventional dress norms of their society.

Attaching larger and bulkier loads to the normal, narrow carrier poses great problems, although the stability of the bicycle would allow a load of approx. 100 kg to be carried in addition to the weight of the cyclist. On a bicycle which is not carrying a load a speed of approx. 9 km/h to 14 km/h can be reached with ease on dirt roads in the plain. On bad dirt roads with a slight gradient of up to 2.5% the cyclist will make an effort and pedal on. But on gradients of 5% over a longer distance a normal bicycle will have to be pushed. On a good dirt road in the plain a maximum load of 70 kg can be transported on a bicycle without excessive effort. But on a slope with a gradient of more than only 2.5% a cyclist will have to get off a loaded bicycle. On a slope with this gradient an additional load of up to 250 kg can still be pushed. On a gradient of 5% and on good dirt roads an additional load of up to 150 kg could probably still be pushed without additional effort. Considerable effort is required to push a loaded bicycle up a slope with a gradient of 10%. A toad of 250 kg could be pushed up a slope like this with an enormous amount of effort, but only at a snail's pace and with many pauses.

One of the reasons why people have to get off and push their bicycles at such an early stage, and that so little can be transported while actually riding the bicycle is that the gearing ratio is much too high for the rural areas in the Third World. Instead of the 5.5 m which are customary at present, a development of about 3 m would be ideal. This could be achieved, if for example. A chainwheel with 28 teeth were used, instead of the large one which usually has 48 teeth, or if the bicycle had an adequate gear-change mechanism.

What has been said about the loading capacity of a bicycle also applies to bicycles with trailers, except that the weight of the trailer itself (usually 20 kg to 30 kg) must be subtracted from the weight of the load the bicycle can carry. As hardly more than an additional 70 kg can be transported on level, dirt roads while riding a bicycle, this means that using the same output of energy, an additional load of less than 45 kg only could be transported in a trailer. This is without taking the higher; railing resistance of a trailer into account, caused by the fact smaller wheel of the trailer and the three tracks a bicycle with a trailer produces.

Tricycles are quite common in Asia, but they are only found in the towns, where they are used for transporting goods and passengers The technical knowledge required for manufacturing them is generally beyond the scope of a rural workshop.

The version with two front wheels is not suitable for unsurfaced roads, since this kind of road requires too much steering power. The driving performance of tricycles with sidecars would not be good on dirt roads The most suitable design is probably the tricycle with the loading surface at the back and two rear wheels. This type of tricycle is driven by an axle on one side or by a through axle, depending on the region; differentials are seldom found. The gearing ratio is usually only slightly smaller than on an ordinary bicycle. In China tricycles with a gearchange mechanism are occasionally found. They have two chainwheels at the bottom-bracket. The chain sits very loosely and a small guiding wheel just in front of the-rear sprocket prevents it from springing off. The gear is changed by moving the chain from one chainwheel to the other by hand.

Vehicles like this are of no use to the farmer in a rural district, since as already mentioned above when describing the bicycles in the Third World, they can only carry a very small additional load on dirt roads, because they have a similar ratio. Tricycles can be ridden at a very low speed, but extremely slow pedalling is very tiring and ineffective. Also tricycles cannot be ridden on footpaths.

In rural areas on dirt roads tricycles as a means of transport only make sense if the gearing ratio is radically changed (development of less than 2 m or even better a suitable gear-change mechanism) and they are built more robustly. The standard tricycle can be used on surfaced roads in fairly flat countryside. Here they could complement or partly replace buses, lorries and community taxis.

In view of the small load that a normal bicycle can carry, special models built for transport can only be of real use if the gearing ratio is considerably smaller (i. e. a development of approx. 3 m). At the same time the railing resistance must not be increased by smaller wheels with a development of 3 m the slowest possible speed is approx. 6 km/h This means that on good dirt roads in the plain a load weighing about 140 kg can be transported on a bicycle, but pedalling a bicycle with a load up a slope with a gradient as low as 2.5% would demand an effort from the cyclist, which he could not maintain over a long period of time.

A gradient of 2.5%, however, is no problem if the bicycle is not carrying a load. and in the plain a constant speed of 14 km/h can still be pedalled. A transport bicycle for the Third World would need a maximum load capacity of 150 kg.

It would be a good idea to develop bicycle more appropriate to the needs of the Third World. The ideal design should take the following points into consideration:

• the transport of loads weighing up to 150 kg; good possibilities for attaching loads
• equally suitable for men and women
• safe accommodation for children and babies
• large wheels with an improved connection between hub, spokes and rim, or possibly sandwich structure
• a development of 3 m, or a suitable gear-change mechanism
• manufactured locally (possibly sheet metal frame)
• as few imported parts as possible
• extremely robust
• maintenance-free
• resistant to dirt, sand, rust and potholes
• the cyclist should be able to carry out servicing and repairs himself
• the price should not be higher than that of the present bicycles.