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A Design for a Strong, Simple, Low Maintenance Utility Bicycle

Summary

This article discusses the design of a simple, inexpensive, low maintenance, functional bicycle. The major design attributes include grease nipples at the major bearings, a steel double diamond frame, standard or smaller wheels, a belt and pulley drive train with manually adjustable multiple gear ratios, springs on the seat and handlebar stem, solid carriers front and rear, and non inflatable tires.

Introduction

This is an attempt to design a modern bicycle that would be extremely functional, almost maintenance free, and inexpensive to produce and buy. Little weight will be given to the recreational and sporting aspects of cycling; this would be a strong, useful tool for those who really need a bicycle, but who are not very well served by contemporary designs.

If such a bicycle finally comes into use, it's place will not be in the Tour de France or in a triple car garage beside a pair of fancy cars, but in an alley, loaded up with garbage bags full of collected returnable bottles, or returning from a market with a child on the back and some rice and vegetables on the front. Campagnolo wouldn't make any money on it, but Shimano might.

All of the ideas put forth here have been tried before, although not necessarily in this context. We are, after all, still building on a late 19th century design. However, the originality in all of this, whatever it might be, is a in a fresh combination of design attributes, as well as the application of concepts from other areas of mechanical design.

Lubrication: Grease Nipples

One of the problems with contemporary inexpensive bicycles is that the cost, including labour, of overhauling them once they are in need of major maintenance work can be more than a brand new replacement. A major aspect of this is the difficulty of getting to the bearings themselves; as anyone who has ever torn down a bicycle knows, it can take hours and hours to pull apart wheel hubs, bottom brackets, pedals and so on, in order to clean and grease the bearings.

To reduce the difficulty of this task, this design includes grease nipples on all major bearings. Of course, a full overhaul would still be necessary after a long period of time, but a semi-annual shot all around with a grease gun might be the only work necessary for years on end.

The grease nipples should be placed at the following locations: the rear hub, one on each side, the front hub, one on each side, the bottom bracket, one on each side, and the headset. (It might be possible to place one nipple in the centers of the front and rear hubs, although it is more desirable to have the source of the incoming grease as close as possible to the bearings that need to be lubricated.)

Frame: Long and Low

The frame would be of steel, in the classical double diamond. There is no end of expertise on every continent in the design and manufacture of this time honoured configuration, and there doesn't seem to be much need to experiment in this area at this point. It wouldn't matter if it was TIG welded or lugged. No brittle, unforgiving aluminum, please.

However, in order to keep the center of gravity on a loaded bicycle low, as well as to keep the cost of manufacture down, the frame could be designed around 20 inch tires, even though it would be made in adult sizes. This would allow boxes or bags to be placed on carriers above the wheels without causing undue tippiness. Also, this would make the bike easier to use by both sexes, in a broader range of clothing; a woman in Africa might prefer a customary longer skirt, while a man in Europe might need to wear a long overcoat for protection from heavy winter rain.

At the same time, the frame would be long enough to allow larger adults to stretch out on it. At least 3 sizes would be in order.

(Of all of the design attributes referred to in this article, this is probably the most expendable. Many cyclists simply don't like the look of a small wheeled bike, and all of the other features could easily be included in a standard framed bike.)

Drive Train: Belts and Pulleys

The last 40 years or so have seen a considerable increase in the use of belts and pulleys in motorcycle and snowmobile drive trains. There are now even a few bicycles, such as one of the newer Moultons, that use a pair of pulleys and a toothed belt, but this practice has not become common.

Roller chains, despite their inherent oily dirtiness, continue to predominate as the drive medium of choice. The essential problem with these is that the surfaces that need to be lubricated cannot be easily accessed, and so the whole roller chain must be kept oiled.

However, the advantage of the roller chain is that it can be used in conjunction with free wheels, cassettes, chain rings, and derailleurs as a major component in a drive train with a wide range of gear ratios.

In simpler bicycles, without elaborate gearing systems, the disadvantages of chains outweigh the advantages; a belt is simpler, cleaner, and easier to work with. The necessary break in the rear chain stay to allow the belt to be installed or removed would not be particularly hard to include in the frame design. The belt would have to be toothed, to prevent slippage, and a tensioner would be necessary, but little else would be needed.

A belt driven bicycle would, of course, benefit from multiple gear ratios. Anyone who has ever used a drill press will know how easy this would be to accomplish. If the front (chain ring) pulleys numbered (say) 3, and the free wheel pulleys the same, it would be quite simple to stop and manually switch the ratios as the loading of the bike and the terrain required. This would be facilitated by a spring loaded tensioner that could easily be set and unset. Its important to note that a belt must run straight between pulleys, and so, 6 (3+3) pulleys would give 3 ratios. (The above linked diagram should help to make all of this clearer.)

The ratios would best be extremely wide. Essentially, the bike would be like a one speed with three different settings; one for hauling a lot of weight or pedalling uphill, one for easy flat work, and one for downhill runs or "scorching." Also, in a more sophisticated version of this design, a 6 pulley arrangement might be used in conjunction with a planetary gear system.

Seats, Handlebars, and Carriers

Many of the newer bicycle designs on the market incorporate suspension systems. However, bikes with suspensions are not particularly good for mounting carriers. At the same time, as we all know, bikes without any cushioning can be jarring and unpleasant to use. Fortunately, the solution is simple, and already well utilized; sprung seats and stems are readily available on the component market.

One very nice arrangement would be a sprung seat post and a very soft seat. However, in terms of cost efficiency, the old fashioned sprung saddle, with two springs on the back, would probably be impossible to beat. Also, a really inexpensive sprung stem wouldn't be very difficult to devise.

This design also would include strong, well-mounted racks, of stamped steel, with tubular stays running down to the bottom of the forks on the front and the chain stays on the back, mounting into strong brazed lugs.

Tires: Non Inflatable

One of the most failure prone standard bicycle components is the inflatable tire. It is extremely easy to get a flat; these can happen at the worst time, and require quite a bit of messing about to repair.

Solid tires, on the other hand, are almost totally failure proof, but have the disadvantages of heaviness and a lack of natural springiness. polyurethane "Greentyres," manufactured in England, are one way around these shortcomings, but these items are expensive and not readily available.

There aren't many solid tires available for bicycles at present. However, these wouldn't be too difficult to manufacture, especially if the huge world oversupply of worn out car and truck tires could be used as a source of raw materials. It might even be possible to make both solid tires and belts in a small, local facility.

This design for an all-out utility bicycle, then, includes solid tires. Years ago, I read (somewhere) about the use of bicycle troops by the Japanese in Malaysia during WWII. These could be heard approaching from quite a distance because the rigors of warfare had long destroyed the pneumatic tires on the bicycles, and so the soldiers had to come clanging along on units that rode on the steel rims alone!

Conclusion

Hopefully, this article has made some sense, both as a particular design, and as a way of seeing that consumer goods could easily be engineered as if the end user mattered. This bike design wouldn't win any races, except, perhaps, for a long, arduous escape from a war or natural disaster. Like the tortoise, it would be engineered for a slow steady pace, and, like this animal, it would be well defended from the depredations of time and heavy use.