Chapter V: Part 5

Screw threads are made rights and lefts, and threads are made to fit them in the sockets where they belong. That pedals may not work loose, the spindles are made right and left, with a reverse screw, so that forward pedaling drives them tighter. In the older constructions, the pedal sometimes became unscrewed and fell off, or the nut fell off and the pedal loosened. All such matters should be studied before taking down a machine. Usually the maker’s catalogue will describe and illustrate these details. Study that, and learn the names and uses of all the parts of the bicycle, and then you will be prepared to go to work by yourself, or with but little assistance.

_CHAPTER XVI._

_Where to Keep a Bicycle._

Almost anywhere that a bicycle can stand or hang will do for a place to keep it; and almost any place will do to go to work on a bicycle--the roadside, the lawn (though the grass is worse than a haystack to lose things in), anywhere, in fact, that may suit your convenience. The accessories of the bicycle should have places where they may always be found, and the bicycle itself should be kept where it will be undisturbed and where it may be kept free from finger-marks, dust, and oil.

With the bicycle should be kept certain conveniences for handling it--a table or bench fitted conveniently, frames to hold the wheel for cleaning and adjusting, a good light to work by, and a place for the tools that are sure to accumulate. There are two kinds of workshop for the amateur--the one that you fit up for yourself, and the one that is fitted up for you. The amateur with a place well fitted out likes to add details of home construction, and the proud owner of a corner cupboard is always anxious to replace makeshifts. In either case, get the best you can, and take care of it. Of tools, the best are always cheapest; but good tools, or tools of any kind, can become a very expensive luxury. Taste for the best comes quickly to even the moderately enthusiastic.

A bicycle rack room should be light, with plenty of head room, and conveniently fitted with racks, shelves, and lockers. Each rack should have its corresponding shelf-room and pigeon-hole, either beside it or above and behind it. There is an infinite variety of racks to select from, from the two stakes driven into the ground or fastened to the floor, to the handsomely finished metal racks with joints to hold the frame at any angle.

If there is but one bicycle to care for, it is better to have its rack and shelf and cupboard together--the rack to hold the bicycle in a proper position, the shelf for sundry attachments, and the cupboard for the lamp and extras. Such a bicycle corner can be made very attractive to look at when everything is arranged and kept in perfect order. When several bicycles are to be cared for together, when neatly set up they make a very pretty showing. If possible, the rack-room should be separate, set apart for that purpose, and kept under lock and key; it should be dry and well lighted, free from frost, and not likely to be over-heated by direct sun-rays in summer. The frost is injurious to metal and enamel; and the sun or too much heat will spoil rubber, and possibly injure enamel as well.

An even temperature, not any special degree of temperature, is requisite; for changes of temperature cause different degrees of expansion and contraction in different materials; and as the steel frame, and the enamel it is covered with, do not expand and contract in quite the same degree, they will gradually work loose from each other, and the enamel will flake or split.

The rubber tire should be kept out of the sun, and the place where it stands should be kept very clean, and no oil allowed about; for oil is injurious to the rubber, and in case of punctures makes repairing very difficult, if not impossible. A rubber surface with even the slightest film of oil will not make a joint, as the oil prevents the rubber surface and that of the cement and the article to be repaired from uniting.

If the workshop is to be used by more than one person, each should have a tool-chest and a work-bench of his own, and each tool-chest provided with lock and key, and each person with a key to the outer door. Tools are but the continuation of the individual brain and will power. What one handles becomes, while in one’s hand, a part of one’s self, as it were. Tools, therefore, should be individual property always, just as scissors and thimble are, though of course extra tools may be provided for general work. Every one prefers a good pair of scissors to a poor pair, and the same preference is likely to be evinced in the case of other tools. If the tools are common property, the best will be always taken, and often not restored to their proper place.

A bicycle workshop is devoted to metal work, woodwork, and rubber work. The metal work should be kept by itself, and the tools used for metal work only.

The amateur can commence fitting a shop by setting up a small deal table and a vise. The table will do for a work-bench, and one vise will serve for a beginning; it should be of medium size, quite heavy, made of wrought iron or cast steel, and capable of holding a wrench in its jaws, though a less expensive one could be made to do. A cheap vise, however, is pretty sure to break if a strain is put upon it; and, while a good workman could get comparatively good work out of a poor vise, the poor tool in unskilled hands would be sure to show its weak place.

Have a notch cut in the edge of the table to let the vise back to where there is bearing surface; and it is well to have it as far in as convenient, for the weight will thus be supported more steadily. Get a plumber to cut a section of lead pipe about as long as the jaws of the vise, and have the piece of pipe split and flattened. You can do this yourself if you can handle a saw, and have one that is suitable for cutting metal; or a jig saw will do, and the lead can be flattened on a block with a mallet. Screw one of the flattened pieces of lead into the jaws of the vise, leaving about an inch to project above; hammer the projecting part over, and one side of the jaws will have a lead face that can be taken out. Do the same with the other piece of lead. Replace them both, and the vise is fitted with a pair of lead jaw faces, which will be found most useful.

The lead being soft, any small metal object may be held between the jaws without injury, while if the steel face of the vise came in direct contact with the metal, a screw for example, the thread might be bruised; or if the screw were harder than the vise, the face of the jaws would be marred.

With a work-table, a vise, and the bicycle kit, a very fair beginning may be made, and any refractory small part handled with ease. Even the spindle of the axles of one of the wheels may be screwed in, and the bearings removed, while held in this way. The vise will act as a clamp for holding pieces to be polished, and it is most useful in taking a pedal or other small parts down. Above the table should be a tool-rack, three feet of board ten or twelve inches wide, with a ledge or shelf nailed along the lower edge, and a strip of leather or some stiff and pliable material nailed on in loops to hold the tools. Under the table should be kept a couple of boxes--wooden boxes such as canned goods come in will do--one as a receptacle for oil-cans, kerosene, and cloths, and the other to use as a frame. The outfit should be completed by a little bench, and a wooden stool to sit on when working at the table; for much of the work about a bicycle may be done while seated comfortably, and it is always well to save strength when possible.

A workshop once started, many little contrivances suggest themselves for convenient working,--a nail must be put up for the apron, a corner found for the working gloves, separate places allotted for oily cloths and clean ones and for the kerosene. The bicycle lamp, if an oil-lamp, should have a stand for trimming and filling, and should be cared for regularly; the best of lamps will smoke occasionally, and the soot must not be allowed to fly about.

From fitting up a bicycle workshop, the transition is easy to studying accomplishments that may be of use--planning tours and trips, exercising scientifically to prepare to enjoy them, studying the construction and improvement of modern contrivances, learning the use of map and compass, investigating camping possibilities, and learning how to depend on limited resources when cut off from supplies. The simple appliances and contrivances of the home workshop lead the mind to appreciation and desire for something better, more workmanlike. A choice of tools suggests itself; and from the first assortment of a couple of wrenches, a few screw-drivers, a hammer, and a couple of wooden boxes, is finally evolved the well-furnished amateur workshop.

The ideal room for this purpose should have a good north light, with windows on two sides if possible, and high enough from the floor to allow a work-bench to be placed in front of the window with the light falling upon it, and a space of ten inches or a foot between the lowest part of the window and the bench; this space to be arranged as a rack for tools. The windows should open and shut easily, and be fitted with two kinds of shades, dark green and white, two pairs of shades to each window, two rolling up from the lower part, and two down from the upper part. Nothing is so fatiguing as working by light not suited to the work to be done. With shades arranged in this way, light may be perfectly controlled, and distributed where needed by means of reflectors. Ventilating and heating, also, must be arranged for.

The workshop should have running water, and a closet for working clothes, which are apt to be oily or greasy. There should be plenty of shelf-room, and an extra cupboard or two. The floor should be of wood, unpainted. There should be a bench for carpenter work and carpenter tools; a bench for cabinet-working tools for fine wood-working; a table for rubber and naphtha; and a long, heavy, narrow bench fitted with vises of different sizes and patterns; a table devoted to the blast furnace, a corner for an anvil and portable forge and another for a lathe and power-saw, though these may be dispensed with. The movable furniture may consist of stools and benches of different heights, and the frames necessary to take down and handle a bicycle on.

Metal can be bent, twisted, cut, pressed, elongated, sawed, stretched, and melted into any shape desired. The tools adapted to this work may consist of holding tools, carving tools, molding tools, and bending tools; and contrivances and tools made to perform certain work, as screw-driver, etc.

Cutting tools are knives, saws, files, and chisels, which perform their work by applied power, whether controlled directly by the hand or otherwise.

The metal-working outfit may contain many varieties of tools.

_CHAPTER XVII._

_Tires._

In the older forms of wheel, the tire did duty in protecting and strengthening the wheel and holding it together. In the bicycle wheel, the rim is the strengthening and supporting contrivance. The tire protects the rim, and acts as a spring cushion as well, receiving shock and jar. The solid rubber tire was an advance over the old steel tire on the bone-shaking machine, as it was called, in the days when the bicycle was still in its experimental stage.

The solid tire was narrow, and after a certain diameter of material was reached, the weight of rubber became too great if the tire was made larger. It was found that a certain thickness of material was sufficient for wear and tear and that more surface was desired to grip the roadway, and that consequently the tire should be made lighter. Hose-pipe was tried, and did well; and then experiment succeeded experiment in the effort to produce a tire that would fit, wear well, be light, and give speed and resiliance.

A pneumatic tire is made of a tough, hard outer material to resist wear, a fibrous inner material to give stiffness and prevent stretching, and an impervious inner layer to retain the air. Rubber is a sticky, gummy substance, easily melted at a comparatively low temperature, and becoming hard when exposed to the air and moderately low temperature; it dissolves readily in benzine or gasoline or naphtha, and is insoluble in water. Grease and oil have a peculiar disintegrating effect on rubber and rubber materials, and are most injurious to them. To prevent rubber substances from adhering to each other, they are prepared in a particular way, and feel dry and gritty to the touch.

Tires are made in layers, and double-tube tires have a separate inner tube of impervious rubber to hold the air, and an outer covering of toughened material, that is quite separate and not necessarily air-tight, to resist wear.

The tire must be held immovable on the rim of the wheel. There is all the pull of the weight of the moving bicycle against the surface over which it moves, and the tire must be secured to the rim in such a way as to keep it forced in place. There are two methods of fastening it permanently to the rim,--with cement or other material of that character, so as to make it a part of the rim, as it were; and by clamping it fast. A cemented tire, or indeed any tire of rubber, should never be left in the sun, as the heat affects the rubber and perhaps the cement.

Changes of temperature affect different materials in different degrees, and the different materials expand and contract, working loose from each other until something gives way, with apparently inexplicable results. When two or more different materials are used in construction in this way, this problem will always present itself.

The tire inflated, the impervious inner covering of the tire tube, which is made of a soft and yielding substance, fills the interstices in the outer covering, rendering it air-tight. Should a hard substance then be introduced into this material, and a puncture occur, it is necessary to locate the puncture. This is very difficult to do if the puncture is small, and the substance that made the hole has been removed. Ascertain first that the trouble is not with the valve of the tire if the air is not retained properly. Then test for puncture in this way. Wet the surface of the tire, and note the bubbles that form under the film of water, and the puncture is found.

The inner surface tire is made to resist the air, and is usually of pure rubber. The outer covering is for strength and wear. Rubber may be repaired with rubber easily enough, and the purer the rubber, the easier it is to cement it with a cement made of pure rubber dissolved in a volatile vehicle. Almost any repair or renovation of the tire may be accomplished with rubber material, rubber cement to be used for plugging, and twine or cotton cloth to be used for strengthening purposes. Small punctures require only plugging from the inside; tears and rents require plugging and reinforcing as well. Each make of tire has its repair-kit and directions for use.

The single-tube tire, with its inner coat, is so made that the inner covering will act as a continuous plug. The soft rubber is compressed, and put on in such a way that the air pressure, even if a puncture occurs, will help to close the hole by pressing on all sides around and about it. To illustrate this principle, cover the outside of the tube with soft rubber cement, and let it dry. Then turn the tube inside out. The rubber will be in an active state of compression. Force air against the surface, and it is easily seen how the rubber is crowded if there is any place made by puncture, and how the hole would be closed.

Numberless punctures are made and resealed, and the tire works all right. The puncture that does not reseal must be plugged or patched. Rubber plugs are made in all sizes; and rubber cement, liquid rubber, is put up in collapsible metal tubes, like paint-tubes, with a pointed spout to introduce the cement behind and through the puncture. There are numberless convenient contrivances made to hold plugs, enlarge holes, and to do the repair work neatly.

In mending a puncture, the tire remains on the wheel, and the work is done from the outside of the tire. If the hole is very small, it must be enlarged sufficiently to introduce the plug. The rubber of the plug is very soft and compressible, and the hole should be considerably smaller than the shank of the plug.

The plug must be held firmly, and forced through the hole, and held in place while the nose of the cement-tube is introduced, and a plentiful supply of liquid rubber smeared over the inside of the hole around and on the plug, and enough extra cement added to flow all about the inside of the tire around the puncture. Pull the plug back by the shank, allowing the head to rest on the inside of the tire, and the shank to come back through the hole. Pull the plug firmly into place by the shank, which should fit the hole very tight. Cut off the projecting end of the plug shank, and the repair is made. Turn the wheel until the plug comes to the lowest point, and keep it there until the cement gets around the plug. To smooth a ragged hole before introducing the plug, when the proper tools are not to be had, a heated wire may be used to make a round smooth hole. Rubber may be handled and cut while wet with water, but must be dry and free from grease to take cement. Always wet the knife-blade before cutting the end off the plug; this will ensure a smooth, clean cut.

A puncture may be repaired by introducing almost any material on the inner surface, and holding it in place; and it is well to know of a few substitutes for the regular repair-kit for emergency use. Punctures difficult to locate may be found by inflating the tire and wetting with soapy water, when a bubble will form where the air escapes.

A puncture that goes all the way through the inner tube of the tire must be repaired on the inside. The outer covering of the tire is porous, and if the hole is plugged or patched on the outside, the air will escape in other directions through the material of the tire. Failing the repair-kit tools, a rubber plug, some liquid cement, a piece of string, and a pair of pliers will do good work. Tie the string to the plug to keep it from slipping, apply plenty of cement to the plug, then grasp it with the pliers, and introduce it through the hole prepared for it in the tire. Pull the string to pull the plug into place, see that there is plenty of cement around and about it, inflate the tire, and the air will hold the plug in place until the cement hardens.

The plugs that are supplied are disks of rubber of different sizes, with stems attached to the centre, and a nice tool is made for the purpose of punching the hole in the tire. When a hole is burned, the charred edges should be removed, and if possible cleaned with benzine. A tire well patched on the inside is almost as good as new, and very serviceable, unless the brake is applied frequently and unevenly, when the plug is almost sure to feel the push.

The commercial patch or plug makes the most satisfactory repair for a puncture, although there are other things that may be used. Rubber bands may be pressed into service, and sheet rubber also may be used. Repair on the roadside is made in the same way as repair in the workshop, the differences being in the conveniences for working and the permanency of the patch. A rent may be repaired with plugs, it being first stitched together, then the plugs introduced, and finally a patch cemented on the outside over the rent to protect the stitches. A puncture may be repaired with rubber bands held in place on a wire, covered with cement, and forced into the hole made in the tire. A piece of wire flattened on the end, a cross piece with a notch cut in it and twisted below, makes a fair repair needle. The end of the projecting rubber cut off, a very fair plug results.

Sheet rubber may be placed over the hole on the inside, though it is difficult to keep it in place. Twisted up and tied into a plug, or spread into place on the inside, the difficulty with this repair is that the patch must be held in place until the cement hardens, and then is liable to work out of place. Inner tube tires are repaired with patches of soft rubber. After the puncture is located, the patch will retain its place by being pressed against the inner surface of the tire when inflated.

To do good work in repairing rubber, always clean the surface of the rubber material thoroughly, washing with benzine when possible; and always test a patch when finished by placing it in water or wetting it, to ascertain that it is satisfactory. On the road a puncture may be plugged in any time under five minutes when located. In the workshop, it is more convenient to hang the wheel up while making a patch, as it is more readily held in place when working from below.

There are many ways of doing makeshift repairs. Melted rosin may replace the rubber cement, and rosin may be found at any tinsmith’s. Melt the rosin, and dip the rubber in that to make it stick.

Tire tape may be used in a variety of ways. Find the puncture, cut strips three or four inches long, and place them lengthwise on the tire, lapping the edges at least half way over; then wrap the two thicknesses of tape round and round the tire, and keep lapping the tape each time over the last turn to hold the edge down, making it air-tight. Well put on, tire tape will last for many miles. The tire should be partly inflated while the tape is being put on, and fully inflated when it is all on. Force more air into the tire to cause the tape to grip securely. Such repair, though not permanent, may prove serviceable in emergency.

A simple and effective substitute for the rubber plug is absorbent cotton or jeweller’s cotton, well dipped in cement, and the cement worked into the cotton. Quite a large puncture may be repaired with this, and the hole need not be enlarged or burnt to receive it, as the soft mass of cotton fills the irregularities in the puncture. It may be introduced into the puncture either with an ordinary repair tool or a piece of twisted wire. The tire is held on the rim by cement made of shellac or some other equally good cementing substance. Of course, in using a cotton plug, the greatest mass of the cotton should be on the inside of the tire, leaving a stem in the puncture, and then the outside ends should be trimmed off.

The tire may be readily removed with the hands by pulling at right angles with the wheel. Rubber cement may be made by dissolving perfectly pure rubber in naphtha; but the commercial cement is usually found the cheapest in the end.

If you should be so unfortunate as to break down, what are the problems you must meet? The bicycle is made of different materials--iron, metal, steel, wood, rubber, and leather, and each different material requires a different kind of treatment. The general idea in any kind of repairs is to effect the holding of the parts in position with a material that will supply strength and stiffness. The use of glue or cement is merely to hold parts in position, to replace the fractured pieces and keep them in place, to enable the particular part to do its duty, and to keep the piece in place while the cement hardens.

There is room for great ingenuity in handling repair work and in estimating the available resources. The most common accident is a puncture in a pneumatic tire. There are also repairs to be considered to the wooden rims and the spokes and the tubing and lost or broken parts. A great deal of damage could occur in a collision, and the bicycle be in very poor shape, but it can be set right with a little assistance from a mechanic, even though he does not understand the mechanism of a bicycle.

Suppose nothing to be injured except a piece of the supporting tubing; or that the bicycle could be made to go if the rim were spliced or strengthened at a place where it has been split. A temporary repair usually takes considerable time, and should never be attempted unless there is nothing else to be done. A blacksmith shop, unless the smith is very ingenious, is not a very good place to look for assistance; a plumber or tinsmith or locksmith, unless a bicyclist, can help but little. For a broken rim I would betake me to a carpenter shop or carriage maker’s. If the break is in a straight piece of tube, get the carpenter to make a round stick, not as long as the broken tube, and fit it to the inside, to slip in easily. Hardware stores keep round wooden rods, and perhaps one of these would answer. Push the round stick up into the tube, and, holding the parts in place, let it slip down into the other part of the break; this will keep the ends of the break together. Then get the carpenter to take two blocks of wood, hollow them out to hold the tube, and screw them fast together, holding the tube between them. If he has an auger-bit the size of the tubing, he can easily bore a hole in a block the size of the tube; then have this block cut in two with the saw, leaving the hole cut in half, and screw the pieces together after they are placed on the broken part. The same kind of a repair may be made on the angles of the frame if the blocks are hollowed to fit. This makes an unsightly job, but can be recommended as strong and safe when properly done.

A broken spoke may be repaired, if it cannot be replaced, by bending the ends of the broken parts into loops; then, taking a piece of wire through both loops, fasten it together, and tighten by screwing it up.

A wooden rim may be whipped or wound. The tire must be deflated first, and removed from the rim at the broken place; then wind fine wire or fish-line about the place, after filling the break with glue or shellac. In wrapping, take care that the turns are made very smooth and even, and close to each other. Then the tire may be cemented and inflated. Of course, there will be a lumpy place on the rim, but it will do until the rim can be replaced.

Any bolt that has lost its nut, when the nut cannot be replaced, may be held by hammering a burr on the end. If the end is too long, a piece may be cut or filed off, and a burr hammered down to hold.

A bicycle cannot travel easily if the frame has been bent out of true; and to straighten a bent frame is an easy matter. Take out wheels, saddle, and handle-bars, and use a piece of broom-handle to spring the frame into true; or take a stout cord, fasten it to either end of the part to be straightened, insert a stick, and wind the cord up tight.

There are three things to take into consideration when doing repair work: First, finding out what is to be done, then doing it, then seeing that it has been done right.

_CHAPTER XVIII._

_Mechanics of Bicycling._

All applied mechanical power is the application of lever movement (and lever movement is but the effect of applied power), either simple, compound, or complex.

In the bicycle propelled by human power, we have a series of lever movements, initiated and executed by the highest and most effective mechanism known--the human body, applied human power. There is the seat of power, the point of application, and the object. The bicycle or object is so constructed that it continues the application of power applied.

The lever is described as “a bar or other rigid instrument having a fixed point for the exercise of power and the application of power to the object to be moved.” The series of lever movements in the human body is the most wonderful known.

There are three varieties of levers, of three different degrees of efficiency, known as levers of the first, second, and third classes, or orders, of levers.

In the lever of the first class, the fulcrum is between the weight and the power:

P F W.

In the lever of the second class the fulcrum is opposite to the power:

P W .
F

In the lever of the third class the fulcrum is opposite to the weight:

P W.
F

These different powers of levers are used in combination, and produce a great variety of power effects and applications.

Other factors to note are:

That a body in motion persists in maintaining its direction unless other forces intervene.

That the gyroscope overcomes the force of gravity while rapidly revolving.

That a body set in motion tends to move in a straight line.

That the centre of gravity must be maintained by balance if disturbed or shifted.

That force is the cause of a change in the velocity or direction of motion of a body.

That all alterations of velocity take place gradually and continuously.

That centripetal force and centrifugal force are force directed by radial action.

That the air offers resistance, which increases when the air is in motion.

That friction offers resistance to power.

That the smaller the surface presented, the less friction there is to resist.

That resistance must be overcome by power expended for the purpose.

That the base of the bicycle is practically without width, and is usually about from forty-two to forty-four inches long.

That the direction of the base may be changed at will within certain limits.

That the bicycle will fall unless prevented from doing so.

That to prevent a bicycle from falling, or to maintain a bicycle on its base, it is necessary to balance it.

That the constant effort to maintain the bicycle upright upon its base is on account of the motion of the different opposing forces.

The bicycle is constructed to overcome the resisting forces in different ways, supplying as many forces as can be made available to accomplish a particular purpose, permitting a certain choice and discrimination in the matter.

The bicycle has one weight-carrying wheel and a frame and a pivoted wheel. The driving power is applied to the weight-carrying wheel, and the steering is done with the pivoted wheel. The bicycle remains upright because several forces co-operate to enable it to maintain its plane, change direction, and overcome certain resisting and opposing forces.

A bicyclist is propelled at a sufficient velocity to maintain the plane of movement. By altering the centre of gravity, inclining one way or the other, change of direction may be made.

The front or guiding wheel of the bicycle, being controlled by the different angles of resistance it presents to the surface it rotates upon, and not being immovably fixed, can pivot to a plane corresponding to a plane of least resistance. After a little momentum is attained, a bicycle will maintain its speed with but little assistance of power, unless it is accidentally obstructed, or an increase of grade requires an increase of power.

The frame of a bicycle is a compound lever, combining the second and third orders. The wheels are a compound lever of the second and third orders. The fork and handles a lever of the second order.

The forks and handle-bars are set at an angle with the front wheel, thus conveying the touch on the ground or other surface to the pivot head and the hands.

A moving body tends to pursue its direction. A wheel loses its power to change its direction after passing the point of friction. With the forks at this angle, the blow is felt, and change of direction caused by an obstacle conveyed; but the wheel has still some power to maintain its plane from friction, and is steadied by its head. The motion of swaying is conveyed and overcome at the tire base. If the pivot were directly over the tire base, the swing would be given to the wheel; and the tire, having passed its point of friction, would continue to swing. If the head were pivoted on a point, there would be no side friction on the rim; because it is pivoted at an incline, the friction base is increased in proportion, and the wheel, steadied in itself, is easily controlled by an increased line of friction or by prolonging the time from the point of contact.

A body in motion persists in maintaining its plane of motion unless additional forces intervene. The occurrence of these forces is detrimental and frequent, requiring a continuous swing of the guiding wheel either by the hands or by balance. The direction of the base line is continually changed, as it were, broadening the base line. The weight must incline with the front wheel, and the front wheel will support it. If inclined away from the direction of the front wheel, the weight becomes the long arm of the lever, exerting weight against weight at the base of the bicycle, there being no opposing force. The front wheel being turned away, the bicycle falls or slips over.

With the fork at this angle the wheel is inclined, the frame held on the wheel at this angle, as the wheel is turned sideways, it gradually brings the centre directly over the axles, raising the front end of the frame up. This pressure or leverage from the frame tends to keep the wheel straight in the line of least resistance. In turning, the wheel must lift the weight, and push it up; and this factor greatly adds to the steadiness of direction.

A bicycle with the steering wheel held fast will maintain its plane so long as its momentum is not overcome. With the steering wheel the plane of movement may be regained after each opposition, provided the proportionate amount of power is expended.

The radius of a wheel is the long arm of a lever; the pedal crank is the short arm of the lever, though its length may exceed that of the radius of the wheel.

Power and speed are interchangeable. The shorter the arm of the crank, the greater the weight required to balance the long arm at the rim of the wheel (an imaginary line). If the pedal crank is lengthened, it will require less power to move it. At the same time the foot, following the crank, describes a larger circle for the distance travelled by the rear wheel. The crank lengthened, the power is diminished, demanding increased exertion to follow it, the foot travelling at a rate determined by the distance to be traversed.

When the hub rests on the axle of the wheel, there is considerable friction to overcome in the entire length of the hub, the friction, or ability of the wheel to turn, depending on the amount of axle surface. The axle, therefore, becomes heated when the air cannot readily reach the surface to convey away the heat generated by friction.

Weight may be balanced and supported on a point; when weight rests on a sphere, only a point supports weight. By surrounding the axle with balls, the weight is taken from point to point on each ball, and a circulation of air allowed. The weight, carried from ball to ball, gives the advantage of a larger cooling surface in a confined space, while the weight and friction are applied directly to a very limited area. Each ball is also an axle in itself, and carries the weight, and passes it on to the next ball. The balls act as lubricators, preventing the moving surfaces from contact.

The problem of speed produced by power means that speed is obtained at the expense of power expended. The relative size of the sprocket-wheels determines the relative speed of the cranks and rear wheel. To get the greatest speed with the least power possible means diminished friction and lessened weight. The band or chain complies mechanically with these requirements, permitting a certain amount of play, which lessens the danger of sudden strains and jars, and supplies the power to the rear wheel with the least possible loss by friction.

Gear 63 72 76 80
6¹⁄₂ crank
proportion 4¹¹⁄₁₃ to 1 ⁵⁄₁₃ to 1 5¹¹⁄₁₃ to 1 6²⁄₁₃ to 1
8 crank
proportion 3¹⁵⁄₁₆ to 1 44¹⁄₂ to 1 33³⁄₄ to 1 5 to 1
6¹⁄₂ crank pressure 4.85 5.54 5.85 6.15
8 crank pressure 3.37 3.84 4.5 5.00
6¹⁄₂ crank ground
covered by large wheel 16 ft. 19 ft. 20 ft. 21 ft.
8 crank ground
covered by large wheel 16 ft. 19 ft. 20 ft. 21 ft.
6¹⁄₂ crank ground
covered by pedal 40.84 inches
8 crank ground
covered by pedal 50.26 inches

“_Scientific American Supplement, No. 1025_,” August 24, 1895.

Rating wheel by the amount of progression for each turn of the crank (pedal), the following table, compiled by Henry Starkweather, will be found of advantage:

No. teeth in 26 in. wheel.
large Sprocket. No. teeth in small sprocket.
6 7 8 9
18 20 ft 17 ft 15 ft 13 ft
19 21 ft 18 ft 16 ft 14 ft
20 22 ft 19 ft 17 ft 15 ft
28 inch wheel.
18 22 ft 19 ft 16 ft 14 ft
19 23 ft 20 ft 17 ft 15 ft
20 24 ft 21 ft 18 ft 16 ft

The following table, from the New York _Evening Post_, shows the gear according to the number of teeth on large and small sprocket-wheels:

Sprockets 28 in. wheel
on pedal crank. Sprockets on rear wheel.
7 8 9
17 68 59¹⁄₂ 53
18 72 63 56
19 76 66¹⁄₂ 59
20 80 70 62
21 84 73¹⁄₂ 65

_CHAPTER XIX._

_Adjustment._

In bicycling, the word “adjustment” means much, for the movable parts of the bicycle must be adjusted to suit the requirements of the individual bicyclist, and the mechanical parts of the bicycle’s construction adjusted so that they will work together properly.

In a machine properly adjusted, the chain and other gear should run smoothly, the chain be neither too tight nor too loose, and the sprocket-wheels exactly in line. The bicycle wheels should run true and be exactly in line with the frame, and the rear wheel follow the identical plane of the front wheel when in place. The frame should be true and square at all points, and should be examined and tested always after the machine has been travelling by rail or has had a fall. The bearings in all parts of the machine should have their cone-caps in place and so screwed and keyed that the balls run easily without perceptible play. Nuts and washers should all be in place and screwed home. The handle-bar should be tight and square with the front wheel, but only tight enough to turn the wheel on a good surface, not so tight as to prevent it from turning easily if the wheel is caught or held. The proper adjustment for position has to do with the frame, wheel-base, length of crank, height and position of saddle; the curve, width, height, and general adjustment of the handle-bar; the size and number of teeth on the sprocket-wheels, which determines the gear; and the weight, construction, and inflation of the tire.

The saddle is one of the most important, if not the most important, part of the bicycle to study, as it should provide the fulcrum to work from. Any saddle may be adjusted to be comfortable, but saddles seldom remain comfortable after being adjusted. The saddle should be hard enough to act as a fulcrum and should not give or spring under work, for power is lost on each stroke that presses down on a soft saddle; it should also permit of change of position without readjustment, unless it is intended for racing purposes, for the bicyclist should be able to speed, climb, or coast on a saddle properly constructed for general purposes. Each of these different kinds of bicycle work requires a different application of muscular power, and the saddle should permit of a readjustment of position that will at least accommodate the altered tendency caused by a shifted centre of gravity in grade work.

Every individual is differently proportioned, with differing lever lengths and lever power. If people differently proportioned find the same adjustment possible, it would be for the reason, not that their different requirements average the same, but that the average of their different requirements is the same. A higher gear means greater resistance; a lengthened crank causes the foot to travel in a larger circle while gaining in increased leverage in the lengthened arm.

In determining the proper proportion of crank length and gear, it may be calculated that the same amount of resistance may be overcome by using a higher gear and longer crank as by using a lower gear and shorter crank, the difference being in the rapidity of the stroke necessary to cover a given distance in a certain length of time. This adjustment may be considered equivalent to length of pace and rapidity of pace in walking. It is well to have crank and gear selected by some one sufficiently experienced to make an intelligent choice.

In the lever action of the leg, working the bicycle crank, care should be taken to prevent waste of power in carrying the foot back and behind, rendering the lever movement useless behind the line where the power may be made to tell. This loss will occur when the saddle is placed too far forward. The foot in returning should supply the pull, and lift with a push-back. The power here gained cannot compensate for power lost on the forward and down thrust, and the saddle should be placed far enough back to permit of the full power of the forward push and downward thrust. The knee should never fully extend when the pedal is pushed to the point where it is furthest from you, for if it is, there is danger in hill-climbing of straining the knee as well as the tendons and muscles of the back of the leg.

The handle-bars should be adapted to the work to be done, whether racing, touring, or ordinary. They certainly should not be high enough to prevent them from taking part of the weight of the body, nor so low as to cramp any portion of the trunk.

Fatigue, with its various manifestations, cramp, stiffness, and numbness, comes from too long a period of work without change of position. For this reason different muscular combinations should be called to do the same work, or different work should be done with unused muscular combinations, permitting rest or partial rest to muscles that have been taxed.

A bicycle should be fitted with adjustable handle-bar and saddle-post, and in case of fatigue or cramp, a slight change in the adjustment will reduce the tendency at once. Travelling should be done with as little weight on the saddle as possible, working on the pedals and resting on the handles. But when it comes to climbing, the push must be located from a fulcrum, and that fulcrum must be the saddle. All weight must be removed from the handles, and the wheel ridden by balance.

A hill should be coasted with the weight all on the saddle, the feet supported, and the handles held firmly and lightly, a proper average position for continuous work being, however, maintained. To carry weight forward, the weight should be forward of the centre of gravity, and the hands dropped.

The question of handle-bars, with the reason of their many varying curves, may pertinently be discussed here. The bar is a pair of levers finding a common fulcrum in the head or centre bar, and the difference in curve has to do with the distribution of weight and the touch best suited to control the bicycle according to position and individual balance and lever power. A distribution of weight and leverage may be made without altering the wheel base by the use of a different pattern of bar that seems to suit the individual touch.

To analyze the curves in a handle-bar, and their different lever values, would be difficult. Preference has much to do with it, and this may be accounted for by the different steering touch of the differently adjusted bars. The forward drop should never be so great that the face cannot be lifted easily and the eyes always able to see up and ahead.

In the tire we look for elasticity, and the amount of air it contains has much to do with the comfort of the rider and the speed of the wheel. Soft tires are adapted for a rough or stony road. The soft tire may wear out a little sooner, but the extra wear is fully compensated by the gain in lessened shock and apparent improvement of wheeling surface. A very hard tire is not necessarily made of rubber. The advantage of the rubber tire is its elasticity, which should come between the fulcrum and the power.

To attain a proper position and its equivalent adjustment, first have the saddle as nearly right as possible so that you can work comfortably; then have the handles and the height of the bar tested, working on these until you can determine if the saddle is too far forward or too far back. Then change the height of the bars to suit the saddle.

Next attend to gear. Find if with comfort you could exert more pressure on the pedals. If so, have the gear increased. If there is cramp in the foot, or the foot feels strained, have the length of crank changed. If the foot is long in proportion to the other lever lengths, lengthen the crank to permit of freer instep play; or have it shortened to relieve a strained feeling in the foot. The crank length may be changed to relieve either cramp or strain in the leg and thigh until the pressure and length are arranged to suit the natural step or pace.

While these adjustments are in progress--and it may take months to determine them--the shoe may cause discomfort. The slightest pressure, a shoe too tight or ill-fitting, would be responsible for much more discomfort than could possibly be caused by either crank or gear. Waist-bands, or any pressure on the trunk, will cause numbness of the foot; and a saddle of imperfect construction or wrong adjustment would be responsible for the same evils--unequal pressure and unequal strains and overcharged blood-vessels, with their accompanying discomforts of cramp, fatigue, numbness, and more permanent disorders.

_CHAPTER XX._

_Exercise._

How shall be determined the proper amount of exercise for any individual? The human body is constructed for use, and will suffer from want of use, rust out, as it were; and it will suffer from over-use if any one set of muscles or any one supply of nerve power is overtaxed.

Exercise, in some form, is necessary for every one; work is necessary; recreation is necessary. Rest is to recreate, to renew. The food that we eat is digested and made into blood; the blood flows through the system of tissues, depositing building material and taking up waste matter. The arterial system, physiologists tell us, supplies the new material; the venous system takes up the waste material, returning the blood to the heart, after which the fresh air comes in contact with the blood in the lungs, and is aerated and oxygenated, and waste material given off. The heart pumps the blood through the arterial and venous systems. When we move or work, more blood is needed, and the heart pumps harder. When little or no exercise is taken, the heart loses its vigor from want of use; and it may be strained if overtaxed.

Brain power and nerve power depend on the blood supply for renewal of their tissue. Any organ or any combination of organs and muscles, when exercised, give off their accumulated material, and then, after a limit of assimilation is reached, the products are reabsorbed. The materials properly accumulate only when needed.

These facts bring to our notice three conditions--a condition of atrophy, or too little use; a perfect condition of equilibrium of forces; and a condition of strain from over-work. In the condition of equilibrium or perfect health, the brain is active and the muscular tissue under perfect control. The mind can receive impressions, and can convey them at will; and the muscles obey without difficulty and without fatigue, because of the great existing power of resistance. On the power to resist fatigue depends the power of prolonging exertion.

In exercising we exert our powers, and if from lack of use or other cause our amount of stored energy is small, exercise for even a very short period will produce a condition which makes rest absolutely necessary. Muscles must be gradually accustomed to work; and if work is prolonged beyond the point where exercise is beneficial, a state of tension and exhaustion ensues which can be remedied only by rest prolonged enough to allow the system to recuperate. Where the tissues, from disuse, have come to have little resistance value, a very gradual and persistent course of exercise must be determined upon, for unaccustomed muscles are quickly fatigued, and the subsequent rest they require may seem out of proportion to the work done. This condition of affairs is discouraging when not understood; yet there can be no different result except in degree; and in degree must the condition be changed and the tissues gradually renewed. If there is but little power stored, only little may be used until the power of assimilation is established.

The thin woman is benefited by bicycling; the liver works better, the food digests better. The stout woman is benefited, for the exercise hardens and condenses the flesh. The average healthy woman is kept in the best of health by the exercise and plenty of pure, fresh air. For the sedentary, the undeveloped, and the insufficiently nourished, the bicycle seems to work wonders. All the powers are accelerated and a general renewing of tissues takes place. The organs of digestion are stimulated and do better work, the appetite improves, the complexion brightens, and the mind responds readily. But people of either of these classes should be careful not to prolong exercise until loss of appetite is brought about; for the exercise should tend to increase, not to decrease, the desire for food and power of assimilation.

Baths should be taken in moderation, the skin being kept in free, healthy condition by dry rubs and tepid baths until the system is brought to the state where the cold bath can be used beneficially. The diet should be generous and wholesome, and care should be taken to avoid food that does not digest easily. Sufficient clothing should be worn but not too much, and all exercise should be avoided that might produce very copious perspiration. Only a healthy activity of the skin should be induced, and plenty of water drunk.

Do not work nervously. Go to work gently, and save your energies to make the wheels go around. A thin person can remain thin and a fat person remain fat while exercising assiduously if the exercise is not properly directed.