For a bevel-gear chainless the method is to multiply the number of teeth in the crank-shaft gear by the number in the rear pinion on the shaft and multiply this product by the number of inches of diameter of the rear wheel; then divide this product by the product of multiplying the number on the wheel hub by the number on the forward pinion on the shaft.
SHAPES OF CRANK AND SPROCKET.
The original crank or rectangular section has for some years been generally round, or of an elliptical section tapering to round at its slightest portion at the end; a few makers have used a bayonet section, or have chamfered out the inner side; fluted sections have also been used, and one or two have brought out a crank in the shape of an S, in the not well-founded notion that it is a good point to depart from rigidity in the driving, or perhaps imagining that a longer throw is thus obtained in the effective portion of the stroke. But there is now a decided reversion to the rectangular and even to the tapered square crank; cranks of bayonet or flattened diamond section are also quite in vogue, notably on the Fauber one-piece construction. There does not seem any considerable reason for choice between round and square, on the score of strength, but the round should hold nickel better, which always shows an inclination to peel on an edge. Still another shape may be mentioned, which has some novelty and neatness—a square or rectangular crank that smooths off into round a few inches from the axle.
Although not new this year, we may mention the peculiar Victor reversal of usual construction by putting the axle on the crank, so to speak, instead of the crank on the axle; the axle is hollow, and the crank stands through instead of over its end. The Spalding crank has on its end a lug or boss which fits a sort of heart-shaped end on the axle, the crank proper being very slightly outside the line of the axle instead of exactly across that.
The Racycle continues its well known peculiarity of putting the bearings of the crank axle within the crank ends, so as to increase the distance between the two ball rows and bring the line of chain pull between them. The Cleveland has a similar arrangement for the same purpose.
There is a disposition to return to the fixed front sprocket in a single piece, as was the construction before the central “spider” with a removable rim attached came into use. The spider itself has been strong enough, but the portions to which its arms were screwed and the rim itself have been rather slight of late, and the toothed rim has not always had support enough. There has therefore been a liability in the sprocket to spring under strain or even to take a “set” out of line, and the change is to be approved on the whole, especially as a very easy detachability in the front sprocket is rather a “talking point” than otherwise, since it is rare that any rider avails himself of it in order to make a change of gear ratio.
Hewitt Brothers, of Cumberland, Md., have a form of sprocket in which the central portion, which comprises the whole except a rim just large enough to have the teeth on it, remains fast and immovable on the crank bracket. This rim, being coned on its inside edge to match a coned recess on the outer edge of the fixed central portion, has a row of balls between and runs around on those balls, just as the intermediate spur gear wheel does on the [Hildick chainless], already described and illustrated. For this sprocket device the usual claim is made that it so increases ease of movement that a gear of 120 with it requires no more power to drive than one of 70 without it.
EVOLUTION OF THE PEDAL.
The old pedal was two elliptical disks of sheet steel, joined in the centre by a tube to pass over the pedal shaft, and having two round rubbers for the tread, on rods which were riveted into the ends of the side plates. The bearing was either plain or the wretched “adjustable cone” already described. Later, corrugated or ovoid rubbers came in; still later, the sensible “square rubber,” for which the Overman people may claim the credit. The same pedals went on the early rear-driving “safeties,” for those not only followed the manner of the high bicycle in general construction as far as could be done, but utilized its actual parts considerably. Probably in the process of paring off ounces of weight, the fixed rubber, of whatever shape, disappeared from the pedal; the serrated-edged or “rat-trap,” which used to be thought fit only for the race track, took possession, and rubber is to this day used only in the form of light and removable slips. These have commonly been of a section like two T’s set end to end, the flat portion being on the inner sides of the tread plates and the roughened T sides forming the rest for the foot. The Wolff-American now offers slips of a triangular section, four for each pedal, which are held by a sheet steel clip screwed on the side plates, and have three edges each, so that they can be turned in their seats to present a fresh surface until worn out. The Straus removable rubber is also simple and practical; it can be slipped over the pedal plate or removed at will, without need of tools, and another form of it can also be slipped over the outer ends of the pedal to take any blow from falls. It does not interfere with a toe-clip.
The pedal shaft grew more slender with other portions. The early ball pedals, by a strange slip backward, were made without a tube to connect the bearings and keep off dirt from the foot, nor did this bad method quite disappear until about a year ago. A recent bad construction which has not yet wholly gone out is the very thin connecting arm and the very light side plate, the whole put together so poorly as to be liable to twist. This has been dubbed the “tin pedal,” and there are pedals today, even on some well-known makes, which have too much of this characteristic. The Wolff-American pedal of 1898 is an example of what a pedal should be in point of quality of steel used and firmness and durability of construction; yet this is not mentioned as if it were the only praise-worthy one, but only as a good example of high quality which comes to mind. No very low-priced bicycle can be found in market with such quality running through it.