Page:The Cycle Industry (1921).djvu/78

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CHAPTER IX

SPRING FRAMES

Like every other road vehicle, there have been attempts made from time to time to spring the road wheels of bicycles. Before the advent of pneumatic tyres these attempts were more frequent, but patents in connection with the springing of bicycles have been exploited as recently as 1902–3.

Omitting the early bow spring used to support the saddle of boneshakers, the first patents in connection with spring frames followed the lines of some of the spring frames now employed for motor bicycles. The rear fork was hinged to the frame near the crank bracket and the spring was placed at the top of the fork between the seat tube and the apex of the triangular fork. One of the first of these was, I believe, the Star, in which a rather large volute spring was used. The Whippet spring frame was an ingenious arrangement of toggle joints and springs by means of which the rider was partly insulated from vibration, but the road wheels were unsprung. This frame was introduced just prior to the pneumatic tyre and had a short life in consequence; had the pneumatic tyre arrived several years later the Whippet frame probably would have met with the success its ingenuity deserved.

Sharp's air spring frame was a device which was exploited about 1904–6, and in this system metal springs were replaced by cushioning devices in which the movement of the road wheels was controlled by air alternately compressed and released by an action that is analagous to the movement of a pump. The invention was clever but it never caught the public favour, partly

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