Cycle Repairing and Adjusting
With a Chapter on building a Bicycle from a Set of Parts

120 CYCLE REPAIRING The effort required to propel the bicycle under such con- ditions is small, and his strength can therefore be use- fully expended in obtaining a comparatively high speed. The contrary is the case when pedalling uphill or against a strong head wind. Then the user of a low gear is enabled to exert the whole of his strength in the mak- ing of a revolution that propels his machine for a short distance only, and although, by the time he has reached the top of the hill, he has expended just as much energy as, but no more than, the user of a high gear, the effort has been more conveniently made, and he has not laboured under any such great strain as the user of the high gear would be subjected to. The Yariable Gear—Until a few years ago, the gear of a bicycle was fixed, and the cyclist had to choose a compromise between high and low; thus, he might prefer a 90 gear for riding under the most favourable conditions, and a 64 gear for hill climbing, and he would choose a gear between these extremes, say 75 or 78, and be obliged to tolerate it for all conditions of riding. Nowa- days, he has the option of fitting a variable gear—an arrangement of intermeshing toothed wheels, by means of which leverage is decreased or increased. The gear may give him either one or two changes, according as to whether it is “ two-speed ” or “ three-speed,” both of which are inaccurate terms. In the “three-speed” hub there may be a normal gear upon which he does the greater part of his riding, a high gear for use when conditions are favourable, and a low gear for climbing hills and riding against the wind. He has to pay, in a mechanical sense.