”The straight fork bicycle might have looked
fine, but the irregular twists, turns, throws and pitches of a Bicycle
Wheel, when attached to a straight fork, were dangerous and unstable--hence,
the name given to the bicycle with a straight fork design: the "Bone
The term "boneshaker" applies to bicycles
built from approximately 1863 to 1878, with a relatively small front
wheel constructed like a wooden wagon wheel--the bicycle shown in
Illustration 6 on the page is of this type. Most bicycles made from
approximately 1878 to 1890 had tensioned steel spokes, a larger front
wheel and a smaller rear wheel. These bicycles had straight forks and
were called "ordinaries", highwheelers" or, with derogatory intent "penny
The rough ride of the boneshakers was due
largely to the solid steel or rubber tires. Highwheelers also had solid
rubber tires, but the ride was smoother--the large front wheel, nearly
directly under the rider, bridged road surface irregularities better.
The rear wheel was small, but it was far behind the rider, and the frame
member between the rear wheel and the saddle was rather long and flexible.
The real breakthrough in ride quality came
with the introduction of Dunlop's pneumatic tires in the 1890s--along
with chain drive, this invention made for a comfortable ride with the
bicycle frame design still in use today.
Straight forks were used on highwheelers
as well as boneshakers. A curved fork does somewhat smooth the ride,
because it is springier than a straight fork--however, its effect in
smoothing the ride is much less than the effect of the pneumatic tires
or the highwheeler's large front wheel.
The boneshaker in your illustration has
a vertical steering axis, a straight fork and therefore zero trail.
It was discovered at some time in the early development of the bicycle
that a bicycle was self-steering (like a supermarket shopping cart caster)
if it has trail--that is, if the tire contact patch is behind the projection
of the steering axis to the road surface. Only a bicycle with trail
can be ridden no-hands. This was the case with typical highwheelers;
the slight tilt of the fork's attachment to the frame created the trail.
With the rear-wheel chain-driven safety
bicycle, the steering axis had to be tilted even further so the front
wheel would clear the rider's feet. Although the fork of such a bicycle
is curved ("raked") *forward* at the bottom, the tire contact patch
is still *behind* the steering axis. A straight fork would bring the
wheel closer to the rider's feet and place the tire contact patch too
far behind the steering axis, resulting a heavy feel to the steering,
and excessive response to shifts in rider position.
What is the provenance of the fork in the
Duchamp construction? It might be from a unicycle -- unicycles still
use straight forks to this day. Or it might be from an old highwheeler,
and cut down to fit the smaller wheel used in Duchamp's construction.
Or, more likely in my opinion, the fork could be from an early safety
bicycle, for example, the "bantam" bicycle shown on page 20 of the book
*Bicycle Science*, 1983 edition (MIT Press), by Whitt and Wilson and
also on page 158 of the wonderful 1896 book *Bicycles and Tricycles*,
by Archibald Sharp (reprint edition from MIT Press, 1979). Many early
safeties had a straight fork. There are other examples of such bicycles
on pages 154, 280 and 288 of Sharp's book.
And in connection with this, the following
statement is not accurate:
”Manufacturers had not produced
bicycles with straight forks for over 30 years Many safeties made
in the 1880s and early 1890s had straight forks. So 20 years is accurate;
30 years is not. That is why I consider it most likely that the Duchamp
for was salvaged from an old, disused safety bicycle.”
I am not a real expert on old bicycles. A
member of the Wheelmen, who collect and restore old bicycles, might
have a more definite opinion of the provenance of the fork. I am sending
this message to the massbike list and Prof. Wilson, who, I'm sure, will
be interested in having a look at your page.