In all experiences with pneumatic tires you will find water the greatest enemy of leaks, and in all cases where one is of sufficient size to be an annoyance, water will surely locate it. The weak point in most valves seems to lie in the plunger that closes the opening through which the air is admitted. Most valves work on the principle explained in the sketch. When the air is forced in, the plunger A is pushed down, admitting the air into D, and so into the tire; and when the downward stroke of the pump ceases, the spring B, assisted by the pressure of the air in the tire, is supposed to push A tightly up against the partition E, and so close the opening. Right here the trouble occurs. For various reasons the spring sometimes does not push the plunger up, and if the pressure is not sufficient to do it, when the pump is removed the air forced in with so much labor blows out in a few seconds. In this case, first drop a little benzine in, as perhaps the valve may be dirty or stuck in some manner, and if this has not the desired effect, it will be necessary to remove the valve. The most common cause of the above annoyance is the spring becoming too much compressed, this being remedied by removing and stretching a little. Frequently the plunger becomes jammed against E, and in pushing it in it disappears entirely within the body of the valve. Here also it is often necessary to take the valve apart.
Puncture.—That is a word that makes every wheelman wince. A little hole in the tire makes the bicycle, that a few seconds ago was a means of travelling, a useless encumbrance. But in this case it does not always follow that it is an encumbrance, for if a pocket repair kit is carried, or the rider can make the best use of things at his disposal, some kind of stoppage of the escape of wind can frequently be accomplished. The single tube, or "hose-pipe," is the easiest to patch up on the road. The leakage can usually be stopped by cementing a piece of rubber over the puncture and binding it on securely with tire tape. Perhaps if the rider is skilled he may effect a permanent repair by plugging it. Now a hint to the rider who goes on the road with only a wrench in his pocket; and if he is given to the chewing-gum habit, it may be of use. A very novel and effective repair for a single-tube tire may be made by a little chewing-gum and some bandages. After locating the opening, apply some freshly chewed gum and work it in, leaving a fair-sized piece on the tire, and binding it with a handkerchief if nothing better offers.
Sometimes a difficult part of a puncture on the road is its location. After examining the tire and noting the likely places, apply saliva at these spots, and when the right one is found, bubbles will be noticed.
The permanent repair of a double-tube tire is to patch the inner one. Let the air out, and if the tire is "cemented" pull it off, and, if the "clincher," spring off, being careful in pushing the valve through the hole in the rim. If it is the "clincher" pattern the inner tube may be readily removed, but if a "cemented" tire, it is a trifle more difficult. In the latter there is a slit about eight inches long in the outer tube, where the valve comes through, which is held together with lacing. Cut this lacing, and the two ends of the inner tube will be seen to come together here. Fasten a string to one end, and catching hold of the other end, pull the tube out, being careful to leave the string in the casing. When removed inflate tightly, and grasping firmly a section between your hands about a foot long, immerse in water and stretch to the utmost; and if the puncture is in this section this will sufficiently enlarge it to permit the free escape of bubbles. Continue this way throughout the whole tube, and when the puncture is located, bite a little piece of the rubber out from around it so that it may be more readily found; let the air out, and cut a piece of rubber to fit over the hole, covering the edges of the puncture and this piece with a rubber cement made for this purpose; and when a trifle dry, place the patch on and put a weight on top. Inflate and test in water for leaks, and if all is right let the air out and fasten one end to the string, which was carried into the outer tube on the removal of the inner one, and by this haul it in place again, lacing up the slot with string. Inflate again, and, after covering the rim of the wheel with cement, place it on and let it dry, revolving the wheel with the rim and tire in water so as to make the cement set.
The method of making permanent repairs in a hose-pipe or single-tube tire is simple—namely, by plugging. A rubber plug with a head like a rivet is covered with cement and inserted in the puncture, head within the tire, and when it sets, the projecting part on the exterior is trimmed off evenly.