HEADERS OR CROPPERS.
“Taking headers,” or, in the parlance of our brethren of England,
“coming croppers,” is perhaps a trivial heading for any article outside
of newspaper or wheel periodical gossip, but it has a popular twang,
and to the fraternity means a great deal. Every rider of the old
Ordinary can give us personal experiences on this subject; among them
will be found mishaps too serious to be chronicled in any jesting mood,
a few so serious that we would fain forget them were not this forbidden
by our sympathy and respect for the sufferers as fellows of our craft.
From this sombre side of our story how joyfully we turn to the many
humorous anecdotes which have been related in every club-room, in some
of which “we ourselves were part of what we told!”
The subject would ere this have been obsolete were it not for a large
number who still maintain the supremacy of the “Ordinary,” and those
others who, forming an intermediate class between the old and new, have
unfurled their banner as doughty champions of the “Rational.”
A header is the act of “going down on the other side,” spoken of in
a former chapter, or, more definitely, it is the projection of the
rider over the handle-bar to the ground in advance of his machine. It
is a simple process, being a mere application of the physical forces
of gravity and momentum. A moving body tends to keep moving in a line
until stopped or deviated by some counteracting force. In riding a
cycle a certain momentum is acquired and kept up against the resisting
forces of friction, impact of air, road resistance, etc. Headers are
a result of a counteracting force, generally caused by sudden impact
against a stationary obstacle on the road, or by the forward wheel
becoming suddenly locked through a failure in the axle-bearings to
work, or by some clog in the wheel preventing it from revolving freely
through the fork in which it is hung. There are modifications of the
header action even in machines of the same sizes of wheels and same
rake,—rake being a term recognized to express the angle of the front
fork from the vertical. This rake has to do with the liability to
headers only in so far as it regulates the centre of gravity of the
system, “more rake” generally meaning that the rider is farther behind
the vertical line through the front wheel axle.
In order to take a header, a certain centre of gravity must get beyond
a certain line. This centre of gravity will vary in position in
different machines, and the modifications spoken of cause the line to
move in a way which is, I think, sometimes overlooked.
If we discuss the crank Ordinary, it will be noticed that when the
front wheel is stopped in its forward progress, the frame of the
machine together with the rider and all other parts of the system
revolve about the centre of the wheel and cause an action within the
system, the same as that of the forward wheel revolving backward
through the fork. Now, it is just when such backward motion is
prevented, that the gravity line moves and alters the conditions,
decreasing the liability to headers. If the forward wheel can revolve
backward through the fork, then, in taking a header, the system,
exclusive of the forward wheel, will revolve about a point in the wheel
centre; but if it cannot so revolve, then the entire system, including
the forward wheel, must all tend to revolve about the point of contact
of the wheel with the ground. Now, it will be seen in the latter case,
or anti-header machine as we shall call it, that as the system tends to
revolve about the point of contact, such point will constantly change;
in other words, the wheel must roll onward, and the point of contact
will therefore advance.
[Illustration: Header action, smooth road.]
In Fig. 1, in the annexed diagram, we show the distance forward and
upward, _a_ to _b_, the rider must be thrown before he gets beyond the
gravity line, _g_, in the Ordinary; Fig. 2 shows the distance when
the wheel will not revolve backward through the fork. In either case,
the header is supposed to be taken on a smooth road and not against
an obstruction; this can easily occur in vaulting into the saddle or
in leaning too far forward. It will be noticed that the distance the
rider is elevated, or, in other words, the amount of work done against
gravity, is in both cases the same, but the distance forward he must
be thrown is considerably greater in Fig. 2. This is for the reason
that while the point of contact, _h_, with the ground remains the same
in Fig. 1, in Fig. 2 the point rolls on to _i_. For more accurate
illustration of the work to be done against gravity, and the distance
forward the rider must be thrown, see the header curves in Figs. 4 and
5, farther on.
We see, then, that the advantage which the anti-header (No. 2) has
over the Ordinary machine (No. 1) is not so very great when in both
cases a smooth road is considered; when, however, we consider the
element of an obstacle in the path, the difference is much more in
favor of No. 2. Let us compare the action of both classes of machines
against a four-inch obstruction. In all cases the action of No. 1
machine will be the same,—that is, the wheel will remain in contact at
_h_, Fig. 1, and the saddle will go on over, just as it does in the
case of no obstruction at all. But in No. 2 the very act of taking
the header must raise the entire weight and roll the system upon the
obstacle, as shown in Fig. 3.
[Illustration: Anti-header wheel action on obstruction.]
The point of contact, _h_, over and beyond which the centre of gravity
must be thrown, will not only move forward, as shown in Fig. 2, but
will move to the top of the obstacle _i_, Fig. 3. Or, if the question
is one of a rut or indentation in the surface of the roadway, No. 2
will be caused to roll partially or altogether out of the rut. Now,
since the rider, by the action of his momentum and that of the machine,
is rolled upon the obstacle or out of the rut, it is easily seen that
if he is attending strictly to his work and is at all a skilful rider,
he can, by a lively thrust upon the pedal at the opportune time, right
himself and keep the drive-wheel rolling on, in which case the rear
part of the machine will, in all ordinary cases, drop back upon the
ground, from which, of course, it will have raised.
[Illustration: Ordinary header curve, any obstruction.]
[Illustration: Anti-header attachment, smooth road.]
[Illustration: Anti-header, four-inch obstruction.]
[Illustration: Anti-header, eight-inch obstruction.]
In the diagrams herewith annexed, Fig. 4 shows the curve of the saddle
of a No. 1 (Ordinary) machine on a level road, and which would be the
same against any obstruction. Scale, one-sixteenth.
Remark how the rider must be lifted from the level _c_ to _b_ and be
thrown forward from _a_ to _b_.
Fig. 5 shows the curve of a No. 2 machine, with the anti-header device,
on a level road. The elevation and forward throw are represented by the
same letters as in Fig. 4; it will be noticed that the distance from
_a_ to _b_ is very much increased.
Figs. 6 and 7 show the curves or necessary projection, forward and
upward, of the saddle in the header act of a No. 2 machine upon four-
and eight-inch obstructions respectively.
The feature of a non-backward revolution of the drive-wheel through the
fork is a natural consequence in some lever and clutch machines. This
element of anti-header has been the subject of an invention in the way
of an attachment to the Ordinary, contrived with a view to reaching
the same result, but it cannot be said to be a successful venture in
the market, the probable reasons being, first, that it interferes, to
a slight extent, in managing the dismounted wheel, the operator being
unable to run it backward, as is sometimes desirable; second, that the
anti-header element has not been really understood or appreciated among
the fraternity, as it does not appeal to the judgment of the casual
observer that any such element results from the fact “that a wheel
won’t run back.” In the lever and clutch machine a third objection is
raised,—the rider cannot back-pedal, but must depend entirely on the
brake in descending hills.
[Illustration: Fig. 8
Header Rational Ordinary.]
[Illustration: Fig. 9
Header Kangaroo.]
[Illustration: Fig. 10
Kangaroo anti-header, four-inch obstruction.]
[Illustration: Fig. 11
Header Star rear-driver lever machine.]
[Illustration: Fig. 12
Header Rover rear-driver type of machine.]
Fig. 8 shows the Rational Ordinary curve;
Fig. 9, the curve made by the well-known Kangaroo;
Fig. 10, the Kangaroo with clutch or anti-header attachment;
Fig. 11, the American Star combination of wheels;
Fig. 12, the curve of the regular crank Rover machine.
The Rover type of safety machine is practically free from the
liability to direct headers, for the reason that the centre of gravity
of the system has to be raised to such a height that the rider swerves
around sideways before he can go over; nevertheless, a modified form
of the same might be possible through some remote concatenation of
circumstances causing the machine to stop and throw the rider bodily
over the handle-bar without keeping him company on the trip as usual,
in which case he, at least, escapes the usual subsequent annoyance of
being pounded by the rear wheel.
A header cannot result from stopping the rotation of the rear wheel, as
generally supposed, because the point of contact of the same being in
the rear of the rider and centre of gravity, the system cannot revolve
about the said point in a forward direction, or direction of momentum.
It will be seen, then, that if from any cause the rear wheel leaves the
ground, which it can do from a rebound against some obstruction, the
instant it does so the system will be simply carried forward by the
rolling of the front wheel.
Headers have been said to result from the above cause in the ordinary
bicycle, but the writer after several experiments has been unable to
attain such a result. Yet it is quite possible that it might occur
from the rebound of the rear wheel in striking an object with great
force, though it is altogether improbable if the drive-wheel were kept
fully in motion. An obstruction so great as to bodily raise the wheel
sufficiently high to throw the centre of gravity over never gets a
chance to act, since the forward wheel must surmount it first, and
this is where the header occurs. It can be easily seen that when the
rear wheel, from any cause, is raised from the ground, there can be
no action within the system to make it raise any higher or to prevent
the forward wheel from rolling onward as usual; hence it is evident
that as soon as the former leaves the ground it will simply drop back
and rebound again at will. But in the other case, if the front wheel
is locked, the rear wheel cannot go on in a straight line and it must
therefore go on over the top.
In the writer’s experiments on the rear wheel, he had an attendant
throw a stick between the spokes while in motion; it was not tried at
very high speed, however, for the reason, perhaps, that any failure
in the theory above provided might end rather disastrously to the
experimenter and thereby cause an act of ingratitude to be perpetrated
upon the prospective patron of this book, through an inability to ever
finish it.
If some ambitious cyclist will kindly complete these experiments, the
writer will gladly incorporate an account of them in future editions of
this work, together with an appropriate obituary notice in large type.