Evening star., 1896-01-11
MYSTERY OF GEARS.

Machines Too Highly Geared Are
Often u Strain to Riders.
From tie New York Times.
The comparative ratings of gears, as ex-
pressed in the present manner, are a sur
vival of the old high wheels, the diameters
Of which varied from thirty-six inches up
ward, and in comparing which riders de-
scribed their mounts by the diameter of the
driving wheel.
When the Safety" as the present form
Of bicycles was then called was first intro
duced, common ground, by which the dis
tance covered by the machine in response
to one revolution of the foot, became the
universal measure. Thus safety "geared
to fifty equaled in point Of progression
fifty-inch high wheel for one foot revolution
The gear of bicycle Is ascertained by
dividing the number of sprockets on the rear
hub by the sprockets on the driving crank,
and multiplying the diameter OF the rear
wheel by the result This result, multiplied
by 3.1416, gives the distance Travelled by one
foot revolution in inches.
The proportions of length of crank to ra-
dius (half the diameter) Of the imaginary
wheel, expressed by the gear, express the
leverage.
In argument, I once made use OF the ex-
preston that a sixty-five gear with six
and-a-half-inch crank was, other things be-
ing equal, the mechanical equivalent or an
eighty gear with eight-inch crank. These
comparisons have since become the subject
of much discussion in the cycling papers,
but have become sort of standard OF com,
parison. For the benefit of the novices and
of those who have never given the subject
any thought, will briefly explain them:
A Asix-and-a-half-inch pedal crank stands
in relation to sixty-five-inch gear (S21:
radius) as I to 5. Ergo, each one inch OF
foot travel causes five inches of progression
In the eight-inch crank and eighty gear
the relation is the same. The difference be-
tween the two is simply this. that very
tall man could use an eight-inch crank with
proportionately the same effort as small
man could a siX-and-a-half crank.
In pedal cranks the same rule applies as
in walking-the tall man.. with the long
swinging stride can use long pedal crank
and a higher gear; the short man. with q
short step, must use the short pedal crank
and lower gear.
On the part of practiced riders there is &
tendency to higher gears. This tendency
has it's various causes.
1t has been said seriously that high gear:
are a great strain upon the frame of bi
cycle. Per Sc. this Is not the case. They d.
strain the rider at times, and they are only
advisable for robust and practiced riders
and then only for the very best roads and ii
| level countries. By high gears 1 mean thos'
from eighty upward.
AS whole. the question of size of gear t!
adopt seems to be more puZZling than whicl
| wheel TO buy. The fact is, that there is NJ
| 'best gear A gear suiting certain per
| son at a C.rtdl1 Tune is just lHe oue He uoe
| not want the following day, because of an.
| of several causes-hills, sandy roads, wind
| heat, or the fact that he is not at par tina
| day.
| The ideal gear lies yet in the future-idea
| things generally do. The best gear woul
| be variable one so constructed that with
| out any complications, additional weight
or friction, it would yield any gear at an,
| moment that the rider might want. 1t ha
| not vet been made, and it will not be fo
some time.