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.