Читать книгу The Modern Bicycle and Its Accessories - Julius Wilcox - Страница 21

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Large sprockets have evidently come to stay, front sprockets having from 18 to 32 teeth and rear sprockets having from 7 to 12; a combination made up of these will produce almost any gear ratio desired.

Chains seem to have settled down to a standard width of ³⁄₁₆ of an inch, and there are many varieties, all having, however, one inch pitch and solid blocks; there are also roller chains, having longer or shorter pitch, but rollers instead of blocks do not yet seem to have taken hold here, as in England.

Chain adjustments—i.e., means for moving the back wheel slightly to or from the crank axle—have been much simplified and improved. A number of variations of the well-known eccentric adjustment are on the market; a few makers are even using the eccentric adjustment at the crank bracket, on singles as well as on tandems. Here is an instance of reversion, the early “safeties” with chain-driving having been constructed in exactly this manner.