The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1895-08-21
The Physics Of the Bicycle,

When wheelman is moving forward
on a bicycle, what keeps him up?
That is the question asked by inqulsi-
tive minds, as the rider passes swiftly
alog on wheel base practically with
out width. Sitting on still wheel is an
almost impracticable feat; but it is
simple enough to maintain an upright
position when moving at a very slow
speed. 1t is a physical fact that
motion persists in maintaining its
plane of motion, and unless some ad-
ditional force acts on the body at an
angle to the original line Of motion, it
will continue to move in it's original
plane until stopped by friction or
arrested by an obstruction. y body
set in motion tends to move in a
straight line, and will do so unless
affected by force acting on it in a
different direction from that Of the first
movement.
TO illustrate this point we night
refer to the rim of hywheel, which
moves in certain plane, but not in
straight line, because it is confined
to circular path by it's spokes. Should
the hywheel burst, its parts would fly
off in paths that would be perfectly
straight but for the force of gravity,
and it is only too well known that these
pieces are not easily DETECTED from the
paths taken by them at the moment
of the explosion
A wheelman is propelled through
space at velocity sufficient to cause
him to maintain his plane of move
ment. Should he desire to change
this plane of motion, as in describing
a curve, he can do it only by calling
in the aid of gravity, i. c., he must
lean to the concave side of the circle,
more or less, according to the radius
of the curve he is following. And
further, in describing curve, he is
impelled outwardly by centrifugal force
which is more or less, according to
his velocity, and he must oppose this
force by centripetal force, which in
this case is gravity. This he does also
by inclining his body toward the center
of curvature Of the path he is describ-
ing. In this case the wheel sometimes
forms a considerable angle with the
ground, so that under some conditions
it slips from under the rider. 1t is in
view of this fact that the circular BIZ
cycle race track at Manhatten Beach,
Coney Island, has lately been con.
structed with considerable downward
inclination toward the center, so that
wheels spinning on this curved track
would be more nearly at right angles
with the surface on which they roll.
The ability Of bicycle and rider in
rapid motion to do serious damage in
a collision with another machine or
with a pedestrian is fully appreciated
by few wheelmen. A man weighing
$50 pounds and moving at the rate of
ten feet per second (which is only about
seven miles per hour) has momentum
of 1900 pounds, leaving out of the
account the weight Of the wheel. This
is sufficient to- upset any pedestrian
with terrific force. It has been sus-
gested that the pneumatic tire forms
a sort Of fender which would prevent
serious conclusion in case Of a collision.
It would undoubtedly have slight
modifying effect, but it would be of
little account. A collision between
two wheels, each with $50 pound
rider, spinning at the moderate speed
of seven miles per hour, would result
in smashup with force of 5000
pounds. In view of these facts, it is
no wonder that bicycle accidents are
often very serious.
The tractive force required to pro-
pell bicycle over smooth level sur
face is estimated at DOL of the load
calling the load $50 pounds, a force Of
u pounds would be required to move
the wheel forward, and this calls for a
pressure on the pedals Of 81 pounds
on a wheel geared in the usual manner.
When, however, the road is rough or
on an up grade, the case is different
On grade of in 10, for example,
the rider in addition to the tractive
force, actually lifts one tenth Of his
weight and that of the machine.
With rigid or semi-rigid tire the
rideris obliged to exert sufficient force
to lift himself over every obstruction
encountered by the wheel the descent
from the obstruction gives back por-
tion of the power expended in sur
mounting it, but not all Of it. In the
case of the pneumatic tire, however,
the small distractions are not an op-
posing element of any consequence, as
the tire yields, in lieu of the wheel
being raised, and the result is the
wheel travels as upon smooth track.
0niontifc Americnn