METHODS OF FASTENING CRANKS TO CRANK-AXLES.
To give any general rule for the cranks removal is impossible, as there are so many manners in use for attaching them to the axle; but, however, the way to remove the several prominent patterns might be useful. We will select four of the general methods, and these will suffice to cover most of the ground. These may be best understood from a study of the accompanying sketches. First, the most common way of putting the cranks on, with a key or pin (No. I). To remove these, unscrew the nut on the pin and drive it out. This might be done at home, but as a rule the pins are put in or become wedged in so tightly that it is frequently advisable to have them driven out at a shop. In the absence of proper punches, there is a great chance of badly mutilating the pin in removal. The second general class is the clamp attachment. There are several patterns in use, but the one described below is most commonly seen (No. II). To free it from the axle the bolt is removed, and it is frequently necessary to insert a wedge to spring the clamps free from it. In the third class the crank fits in a continuation of the axle, usually projecting a little, so as to permit locking with a nut (No. III). Sometimes it passes a little to one side of the centre, and, again, exactly through it. The fourth and last general class is where the axle and cranks are made in two forgings, as shown by No. IV (sketch represents a cross-section of barrel), the part shown being half, and the two sections fitting together by teeth. These cranks are removed by unscrewing in the opposite direction to which they revolve in the propulsion of the machine.
DEVICES FOR TIGHTENING CHAIN BY MOVING REAR AXLE.
The next part of the wheel we will turn our attention to is the chain—the medium through which the motion is imparted from the driving-gear to the rear sprocket. Frequently after a long ride on rough roads, or perhaps a few days of usage, the chain will be found to have slackened up considerably. There are many devices in use for taking up this slack—all of them, however, working on the principle of moving the rear axle back and forth, and being more or less improvements of a few general patterns. In device "x" in the sketch, after loosening the nut, the axle is moved backward or forward by turning the screw in the proper direction. If it is desired to move the axle back in "y" the screw is tightened, or if it is desirable to move it forward (nearer the cranks), the screw is unscrewed, and the axle pushed forward by gentle taps with a wrench. In "z" the whole bar swings with the axle. This adjustment is tightened or loosened in the same manner as the preceding one, with the exception that the nut on the bolt holding the upper end of the bars has to be loosened a trifle. In "w" the axle is adjusted without the aid of a screw. When in the right place, it is held by the tightening of the nuts, teeth in the washer engaging others around the edge of the slot.
No part of the machine collects the dirt more quickly than the chain, it being found liberally sprinkled with grit after every ride. As long as it runs smoothly and quietly it does no harm, though when it gets rather thick it would be best to wipe it lightly with a rag or a stiff brush. When a chain is dry or very dirty it shows a tendency to kink, at the same time producing a rattling noise, joined with sharp snappings. When in this condition, it should have a thorough cleaning. First wipe with a rag, and then remove the chain from the sprockets; put it in kerosene oil to soak, wiping dry with a rag. The only troublesome part of the cleaning operation will be to replace the chain. This is effected by passing one of the ends of it over the rear sprocket, joining them with the screw-bolt, then, catching some of the links on the top teeth of the front sprocket, revolve it, and this will spring the chain on.
The mentioning of a "dry" chain brings up the subject of chain lubricants. There are a great many on the market, and as to their relative values riders differ in opinion. Two facts are clear, however. If a lubricant is too liquid it collects grit very quickly; on the other hand, if too dry, it does not work in the joints of the chain properly. Oil is obviously, from the above, very bad, and should only be used on the road when a chain unexpectedly runs dry or hard. The prominent constituent of most lubricants is graphite, the different makes varying usually in the amount of oil or other dissolving agent contained. Some wheelmen recommend powdered graphite alone, but my experience has found a mixture of graphite and oil having about the constituency of vaseline to be very satisfactory. Whatever the lubricant, they should all be applied in the same manner. Rest the step of the bicycle on a box or anything, so that the rear wheel may revolve freely, and apply lubricant rather sparingly; too much will only serve to collect dirt. Spin the wheel rapidly for a minute so as to permit it to work into the joints, and then, slowly revolving, wipe the waste off the top of the chain.
We have now reached in our discussion of the bicycle a part just as essential to the running ability as anything previously mentioned—the tires. On account of the wear and tear upon the tires, from one cause or another, they require much care. It is the tires that take up the jolts from the inequalities of the road, and upon their proper degree of inflation depends the easy running of the wheel. Quite a study may be made of this, the pressure varying for the different uses the wheel is to be put to. Without exception the rear tire should be harder than the front; if the latter is more tightly inflated than need be, it creates unnecessary jarring, which manifests itself in a numbing of the wrists. For riding over city pavements the softer the tires, without endangering the rims, the less jolting; but on good roads hard tires are best, as there is less friction, due to a smaller surface presented to the ground. From the inflation we will turn to the valve, the most important part of the tire. This is frequently a source of much annoyance from leakage. Whenever in doubt as to the valve's effectiveness, immerse it in water, and the air-bubbles will soon show the size and location of a leak, if there is one.
TIRE VALVE.