The bicycle having reached this point in its development, it only remained for the process of evolution to produce the present standard form of "Safety" machine, shown in Fig. 4, which is largely in use by persons of both sexes, from the child to its grandparent.
Having all the favored appliances of the most approved ordinary roadster, such as cushion etc., this machine possesses the elements of safety and speed to an almost perfect degree.
The front wheel is used for• steering and the rear wheel for driving, both being of the same diameter. viz., usually in., geared to 54 in.
Th, pighd-shan is carried in the frame just in front of [he driving-wheel, its center being slightly lower than that of the wheel, and an endless chain imparting motion front ['sprocket wheel upon one end of this pedal-shaft to a wheel of the proper relative size on the driving wheel a-ale. The bracing-Liars of the frame, all of forged steel, are arranged in different ways —a preferred form of frame in men's bicycles being that of an elongated diamond, the sharper apexes being at the rear axle and front fork, and the other angles occurring at the pedal-shaft and the point where the saddle is supported, a cross-bar lying between the two latter. The front fork is rigid, and made with a curve and " rake" rearward from the front-wheel axle, so that the handle-bar may be within convenient reach of the rider's hands, and the saddle lies just over the front half of the rear or driving wheel.
The Ladies' Bicycle (see Fig. 5) is similar to the above in all respects, save that the back bone of the frame extends downward from the head of the fork close to the rear part of the front wheel, and then curves underneath to a junction with the pedal-axle. Skirt-guards are provided over the moving parts adjacent to the rider's sent. For ladies use, the present standard diameter of wheel is 2S in., geared to 50, in. The brake is of the plunger type in both machines, and is applied to the driving-wheel, and the handle-bar is a single tube of seamless steel tapered at each end and curved backward, to bring the grasping pieces, which are of rubber, within easy reach of the rider's hands.
The spokes preferred in these standard " safety " machines are of the double-tangent type.
As a result of continued and practical investigation by experts in this country and Eng land. an efficient anti-vibration device, in addition to the cushioned tires and hubs, has been deemed an essential part of a high-grade modern bicycle ; a yielding spring-fork, of which that named the " Victor" is a leading type, has been largely adopted.
It is of especial value for rough-road riding, where obstacles are frequently tact with, and great strain consequently brought to bear upon the machine.
The front fork consists of two steel bars " raking" backward from the axle of the front wheel, and pivoted to short links, which are also pivoted to the head, which practically forms part of the frame. Two strong steel springs, bowed toward the rear, extend from the steering wheel axle, one on either side of the wheel, to a rigid connection with the lower part of the head. The springs carry foot-rests. By referring to Fig. 4, the action of this spring-fork will be understood without further explanation.
The spring-fork is equally applicable to ladies' bicycles.
The Otto Bicycle is the invention of a brother of the inventor of the gas-engine bearing the same name, a-nd probably is the only one of its class, it being believed that no other bicycle exists in which the whole weight of the machine itself, as well as the full weight of the rider, rests upon the driving-wheels.
It is in some respects more nearly allied to a tricycle than to the bicycle proper, but, as it has only two wheels, and consequently requires the balance to be still maintained by the rider, it is rightly called a bicycle. The wheels are of equal size, and are here mounted loose on the same axle, parallel to each other, and both of them are drivers. The rider sits between them, and works a continuous pedal erank-axle, the position of which, when he is seated, is below and slightly in front of the axle carrying the driving-wheels. The crank-axle is con nected with the driving-wheels by endless steel bands passing around plain pulleys on the ends of the crank-axle and on each wheel. The bands are kept taut by tightening springs, and the machine is steered by slacking one or other of them, which causes the corresponding driving-wheel to lose motion, and therefore the other wheel overruns it. If a sharp turn has to be made suddenly, a brake is applied to one wheel at the same time that its driving-band is slackened, which causes the machine to turn round in a circle upon that wheel as the center. This machine, having no small wheel fore or aft the rider, while steadv sidewise, has to balance himself in the direction of his motion, which he is enabled to do through the medinnt of the pedal crank-axle : by pressing on the forward pedal, if he is falling forward, he throws his weight backward; and by pressing on the rear pedal, if he is falling backward, lie throws his weight forward. T m pressing prevent hint actually cap%izing backward, a safety-tail projects behind upon the ground whenever the seat is tipped too far back. Among the many beauti ful features presented by this machine, the best seem to be : Firstly, its balance, whereby the rider is id ways in the best position to utilize his strength and weight, notwithstanding the varying gradients ; secondly, the nicety with which it can be steered ; thirdly, its tendency to run in a straight line without any effort on the part of the rider; fourthly, its freedom from vibration; fifthly, the circumstance that it makes only two tracks; and, sixthly, the perfect distribution of the wheel-load.
The power required to propel a bicycle on an average road has been approximately esti mated at from + to # Ida horse-power, according as the speed varied between Ii and 14 miles per hour, with the odds in favor of a rotary-action against a lever-action machine.
Tandem Bicycles.—One of the earlier machines of this class is constructed of two ordinary bicycle driving-wheels complete in their forks, which latter are connected by a backbone, having in its length a swivel or axial joint. Each rider drives his own wheel, sitting just behind its center, mad each steers independently of the other for balancing himself. The axial joint in the backbone, and the joints formed by the heads of the forks and the hearings of the wheels, together make a perfect universal joint between the two wheels. Within cer tain limits the rear rider has of course to follow in the track of the front wheel ; otherwise the heads of the two forks become locked. and a dismount is rendered necessary. Although this machine is very fast, lighter than two ordinary bicycles, and almost entirely free from vibration, there is an element of danger about it that militates against its general use, inas much as it demands to a certain extent a unity of thought and action on the part of the two riders.