Читать книгу Bicycling for Ladies. The Common Sense of Bicycling; with Hints as to the Art of Wheeling—Advice to Beginners—Dress—Care of the Bicycle—Mechanics—Training—Exercise, etc., etc онлайн
22 страница из 27
As the wheels revolve, there is a constant pull on tire and rim. Just as the chain is pulled over the sprocket-wheels, the tire is pulled by friction over the surface ridden on. If this surface affords the tire no hold, it is impossible for the wheel to advance, as on a muddy surface. The crank may impart a motion to the wheel, but this motion will not enable the wheel to maintain its place; or if, in overcoming the cranks at the dead centre, too much weight is applied to one side of the wheel, the same thing occurs, and the wheel falls over. There are a number of mechanical means for conveying the motion of the foot to the wheel of the bicycle to cause the wheels to revolve.
There are many ways of constructing a frame, and different designs and patterns of fittings for different parts; but the main idea of the bicycle does not change—a fixed wheel to which motion is imparted, and a movable or guiding wheel, independent of the power wheel, and revolving only because the machine is pushed or pulled forward. This second wheel gives stability, and supports the wheel at a movable point.