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.