An article in the Glasgow Argus of 1842 said that a gentleman of Dumfriesshire had
ridden 40 miles from Old Cumnock to Glasgow - in five hours - and there
in a crowd of spectators had mounted the pavement and knocked over a
small child. Luckily the child was unhurt and the gentleman was fined
only five shillings.
Later development
In the 1860s pedal-driven
bicycles were made by Michaux in
Paris
; they were called boneshakers or velocipedes,
depending on whether you were impressed more by their painfulness or by
their speed. The ‘ordinary’, high bicycle, or penny-farthing came
along about 1870. This was a sensible development. Drive to those early
bikes was by pedals attached directly to the front wheel. There were no
gears, and usually no brakes; you slowed down by back-pedalling.
Assuming that there is a natural rate of pedalling (‘cadence’), the
speed of a bicycle with direct drive depends on the size of the driving
wheel; with a front wheel six feet across you could go three times as
fast as with one two feet across.
There were considerable
disadvantages. Getting on to a high bicycle is tricky - I know; I have
done it. You need either a mounting block as used for getting on to a
horse or a good deal of courage and skill to push forward, put one foot
on the foot-rest low down, and then vault into the saddle as the bike
moves off. Riding also is nerve-racking, since you are perched about six
feet off the ground.
Once going, the high bicycle is
more stable than a modern bike, because the huge front wheel produces
lots of rotational inertia - like a flywheel which once spinning is
extremely hard to twist. I am told you can ride hands off the handlebars
at 2 m.p.h. However, if you hit a serious bump or pothole you go
straight over the front wheel and land on your face from a great height;
many cyclists were injured this way. Even getting off is an acquired
skill. Partly because is was so terrifying, and partly because it was so
fast, the high bicycle was tremendously popular with young men in the
1870s and 80s. Its demise started quite suddenly in 1889.
Pneumatic tyres
The credit for inventing the pneumatic tyre usually goes to John Boyd
Dunlop, the Scottish vet. The Dunlops were living in
Belfast
, where young Johnny complained that on his tricycle
the cobbled streets made his bottom sore. His dad thought he could
smooth the ride with a cushion of air; so he got hold of a thin rubber
tube, glued the ends together with rubber solution, stuck in a valve
from a football, and so made Johnny an inner tube. To fasten it on the
wooden wheel, he nailed strips of canvas – or strips torn from one of
his wife’s old dresses - over the tube and around the rim.
The reason the pneumatic tyre
works so well is that the air cushion in effect irons out the little
bumps in the road. When a solid wheel goes over a stone, the whole wheel
and therefore the whole bike is thrown into the air, which is
uncomfortable for the rider and also wastes energy. When the pneumatic
tyre goes over the same stone, the tyre squashes a bit but doesn’t
rise. So you hardly feel a jolt, and although some energy is lost - and
goes to heat the air inside the tube – compressing the air loses much
less energy than is necessary to lift the bike and rider off the ground.
Dunlop’s
tyres turned out to be not only comfortable but also fast; he persuaded
leading local cyclist Willie Hume to use them for an important race at
the Queen’s College playing fields on
18 May 1889
. When Hume turned up not on a high bicycle but on a
safety, and fitted with the silly new tyres, everyone laughed at him.
But they stopped laughing when Hume won the race. Then everyone else
wanted pneumatic tyres too - and in due course the Dunlop Rubber Company
was formed.
However,
Dunlop’s were not the first pneumatic tyres, because 43 years earlier,
in 1845, another Scot, Robert William Thomson of Stonehaven, had taken
out a patent for ‘the application of elastic bearings round the tires
of the wheels of carriages for the purpose of lessening the power
required to draw the carriages, rendering their motion easier, and
diminishing the noise they make when in motion.’ Thomson made his
pneumatic tyre from a hollow belt of canvas, saturated on both sides
with india rubber or gutta percha and cased in leather, and bolted it to
the rim of the wheel. He inflated the tyres with air through a pipe
‘fitted with an air-tight screw cap.’ There is no mention of a
valve; so the process of inflating the tyres must have been tricky.
The
bicycle had scarcely been invented, and the motor car was far in the
future; so Thomson’s tyre was designed for carriages. Thomson wrote
‘the comparatively small amount of power required to propel carriages,
the wheels of which are fitted with these belts, the steadiness of the
motion, the absence of all jolting and consequent security of the
machinery from injury, the small damage the carriages will do to the
roads, the absence of nearly all noise, the high speed that may be
safely attained, and the great gentleness of the motion, will, I think,
enable steam carriages to be run on common roads with great
advantage...’
Most
vehicles then had solid tyres, generally made of iron shrunk on to
wooden wheels. In 1847 Thomson proved that these were inefficient, with
a series of tests in
London
’s
Regents
Park
. He took two horse-drawn carriages, fitted one with
his elastic bearings, and compared their performance over two different
types of road.
The first thing that everyone noticed
was that the carriage fitted with his tyres was silent, whereas iron
tyres always made a loud grinding scrunching noise as they rolled along.
His carriage caused quite a stir among the crowds in the park; The Mechanics Magazine concluded: ‘Despite the opinion most people
would form...that the draught [i.e. the force needed to pull the
carriage] must be greatly increased, (it) is unquestionably much
lessened. The tyres are perfectly elastic as well as soft. They do not
retard the carriage - they yield to every obstacle, permit the carriage
to pass over it without rising up, and expanding as they pass from the
obstruction, return the force borrowed for a moment to compress the tyre.’
Thomson
found in his tests that the force needed to pull the brougham was 60 per
cent more for the solid tyres than the aerial wheels on the macadamized
(smooth) road, and three times as much on the rough road! Perhaps his
elastic bearings would have been a commercial success had the bicycle
been invented earlier, but sadly for Thomson they were ahead of their
time.
This article has been developed from Adam Hart-Davis’s book Eurekaaargh!,
about inventions that nearly worked.
Eurekaargh,
1999
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