CRANK THROW AND VARIABLE GEAR.
THE RAMSEY PEDAL.
The crank, like the axle and most other parts, used to be very thick and heavy. As the quality of steel was improved and a more exact knowledge was obtained of the relative strength required through the parts of the structure, the metal was gradually pared away; in fact, there could be no better object lesson of bicycle evolution as a problem in mechanical work than to compare, side by side, the axles, cranks, hubs and pedals of today with those used in 1878. The old slot for variation of crank throw, sometimes replaced by three holes, disappeared from the crank long ago. Right here we might say—without stopping to consider the topic at my length, because it is not at present in agitation—that two-speed or three-speed gear and variable pedal stroke, while a tempting subject for inventors, are not and never can be really practical in the complete sense. To exchange power for speed or vice versa at will, so that one may vary his “gear ratio” to suit surface and circumstances, is indeed desirable; it is not in question that if one could drive the driving-wheel as fifty or as 120 or as anything between at pleasure it would be a consummation devoutly to be wished—but this cannot be done. If lever-driving is used, which is the most manageable mode for this particular object, a variable leverage can be obtained; but the offsetting disadvantages, which are not small, must be accepted too. As for shifting gears, they allow only two speeds, and it is not wholly easy to decide in advance what two are on the whole best; when the choice has been made one is sure to want more than two and almost sure to be as little satisfied as before. Moreover, the weight, complication, wear and cost of these devices are obstacles which must ever bar them out.