On the model 4 [Humber] is shown a rear fork chain adjuster, which is similar in construction to the chain adjusters in use on the Humbers made in England. The rear fork ends instead of being carried horizontal as before now slant upward at an oblique angle, and the backstays instead of being brazed to the rear forks as heretofore are separate and are carried backward or forward, as the case may be, with the rear axle to tighten or loosen the chain, the object of this change in construction being to cause the backstays to help carry with the rear forks the weight of the rider on the axle.
The [Wolff-American] patent eccentric chain adjuster is almost too well known to need describing. Still it is such a radical departure, and withal such a good one, that it will bear describing here again. A square groove or spline is cut on the sides of the rear axle, running about an inch from the end. A pair of eccentric disks, having a tongue or key to fit this groove, are slipped on the axle, thus becoming, as it were, a part of the rear axle. They are then placed and held in the frame by semi-circular braces, which are a part of the frame. The chain is adjusted from one side, the eccentrics acting together. By loosening one nut on each side the eccentrics are free to move either way. This completes the operation, and, it is needless to say, one need not worry about getting the rear wheel out of line or readjusting the bearings, because with this eccentric adjuster neither is disturbed. They use the same method of adjustment on the rear wheel of their tandems, but the front chain on the tandems is adjusted with an eccentric at the front crank-hanger, same as most of the other makers use in tandem construction. Nearly all the makers who make tandems adjust their rear wheel, however, with their regular form of chain adjuster as used on their singles, a variation of this, however, being to adjust both chains at the crank-hanger brackets with an eccentric adjustment.
Another variation in chain adjustments on tandems consists of bolting the crank bracket to the frame so that by moving the crank bracket forward or backward the chain can be adjusted to the proper tension. The makers of the juvenile “Elfin” not only use this form of construction on their juvenile tandems, but also on their single models, and have in addition to that a method of reversing the bracket, so that it can be either bolted on top or underneath the rear forks which permits an adjustability of two inches between the seat posts and pedals, by which an Elfin may be made to last a growing child for several seasons.
HUMBER CHAIN ADJUSTER.
CHAPTER VII.
HUBS, SPOKES AND RIMS.
The wheels of the 1898 bicycle do not present any very remarkable or striking novelties in construction. The old style of slender cylinder hub with broad flanges has, however, disappeared, and the tubular or barrel hub, with or without flanges, is the only one in use. But before surveying the state of the art for this season let us take a look backward and see what led up to the present types. At the Crystal Palace, London, England, was exhibited in 1889 a bicycle that was built by Gavin Dalzell, a Scotchman, some time previous to 1846. This was described as “being wonderfully strong, especially in the wheels,” these seeming to have stood the ravages of time and rough usage much better than the framework. The rear wheel, or driver, was of wood shod with iron, about 40 inches in diameter, and had twelve spokes, each about one inch in diameter. The front wheel was of similar construction, but only about 30 inches in diameter. The wooden velocipede of 1866 usually had wooden spokes and flat iron tires, and about that time a very crude high wheel was built in England by S. Madison, and this in 1868 was improved upon by Edward Cooper. In 1869 the bicycle called the “Phantom” was put upon the market. It had wooden rims with rubber tires nailed on. On the inside of the rim were staples, through which the wires were passed and screwed at the centre of the wheel. It was really the first practical suspension wheel ever built, its one fault being its liability to get out of order and the inability of the mechanics of that time to true it up again. James Starley brought out a bicycle a little later called the “Ariel,” which had “lever tension” wheels and was popular. It had double wire spokes and steel rims, and at the axle of each wheel was placed a lever bar.