Page:The Cycle Industry (1921).djvu/79

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65
SPRING FRAMES

due to increased weight and the average cyclist's objection to complication.

Spring forks were far more common than spring frames, and it is rather surprising that they are almost obsolete on a modern bicycle. Among the pioneer front spring fork inventions may be mentioned the Dunlop. In this design the wheel was carried in jointed links which were connected to the fork blades by interposed spiral springs.

A Nottingham firm, at a later date, made the fork blades or sides like a small carriage spring of two to three leaves of flat spring steel, the flat part of the leaf facing the direction of travel. This form of spring made the machine very comfortable to ride but was said to detract from the rigidity of the drive when the bicycle was pedalled up steep hills; the blades or leaves were also liable to fracture.

Following the withdrawal of this last type of spring fork the question of springing of bicycles has lain dormant, and shows no signs of revival.

The principal objections to springs from a mechanical view point are that they add weight and complication to the machine; they interfere with the action of brakes and render them far more difficult to fit; the joints wear and adjustment devices have to be designed which are costly to produce, and however well made the joints may be, they are almost sure to rattle.

To sum up, the objections appear to outweigh the advantages of this method of insulating the rider from road shock when the pneumatic tyre absorbs so much of the vibration at the point of contact of the wheel with the road surface.

In addition, the rider, if he be skilful, can act as a natural spring by partly lifting his weight off the saddle and supporting himself to some extent on the pedals.