History and evolution of Bikes

It is believed that engineers have been dreaming up
different versions of bicycles since the 1500s. According to IBF (international
Bicycle frame) iterations of bicycle frames had existed a long time before we
started using it as a mode of transportation. According to the data that has
been found it points to an Italian engineer named Giovani Fontana and credits
him for the beginning of what led to the modern day bicycle. Although to keep
in mind what he had created some 600 years ago had very little resemblance to
today’s bicycle, it had four wheels and a loop of rope connected by gears.

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Some 400 years later the world as a whole faced a shortage
of horses brought on by the eruption of mount tambura in Indonesia which led to
the ash cloud dispersing all around the world, the effect of this ash cloud has
been such that it lowered the global temp which in turn meant that crops
started failing around the world and animals including horses started dying.

To battle the shortage of horses In 1817 Drais came out with
a two-wheeled vehicle which came to be known all around Europe as the hobby
horse. The hobby horse had been reported to have weighed in at 23kg, had 2
wheels attached to a wooden frame, an upholstered leather saddle was nailed to
the frame in order for the rider to sit on and steer the vehicle with a
rudimentary set of wooden handlebar. This design of Drais had no gears nor did
it have any pedals leaving the riders to push the device with their own feet
while sitting down in a rather awkward position.               

Fig 1

Soon after it made its introduction in UK, A British coach
maker by the name of Denis Johnson concocted his own version. According to the
National museum of America by 1820 the popularity of these bikes had faded away
due to the respected countries banning the bikes in sidewalks. This was due to
them obviously being a danger to the pedestrians as they were unsteer-able.

In 1860 bikes made a comeback due to the addition of pedals
and fixed gear system, although as to who to credit for this modern alterations
is still a topic that is covered in ambiguity. The ride was so bumpy that the
first riders brave enough to go on one of these titled it the bone shaker
although the more famous name is velocipede. During these period the wood was
going out of fashion for being the main choice for a bike frame and Metals were
stepping in, this transition allowed for the bike frames to be built more elegantly
and metal being stronger than Wood and thus allowed the usage of less material
for a stronger frame which reduced the frames Weight and allowed it to be
manufactured more rapidly and reduce production cost, this ultimately increased
the Market size of bikes.

A German engineer named Karl kech claimed that he was the first
to attach the pedals and gear to the hobby horse although he was unsuccessful
in his claim and the patents in fact went to a French carriage maker named Pierre
Lallement.

Fig2

  Few years afterwards another problem arose, the
consumers wanted to go faster. There were 2 different options to take in order
to make the bike go faster either change the gear ratio of the bike and make
the drive train indirect or change the size of the wheel that the pedal was
stuck to. Herein lied a problem in the fact that although the direct drive
train was a revolutionary step forward for bikes it meant that the only way to
increase speed for bike was to increase the diameter of the wheel the pedal is
stuck to. Increasing the diameter of the bike would mean that the bike would
travel further per revolution that the wheel takes, but engineers had another
problem to tackle in this field as well, the wheels of that time were too heavy
to increase it any further.

In 1869 wire spoke tension wheel was created, this kicked
off the start of larger front wheels for bikes. This new invention was so good
that it has been reported that front wheel of bikes around that time had
reached up to 5FT. This was named “Penny farthing” although it was claimed by
adverts of that time the bike was lightweight it still weighed in at staggering
40 pounds.

 

Fig 3

Although this was a very simple solution to a complicated
problem, it caused yet another problem. The riders themselves were falling off
of the bikes and the height being so great from the ground fairly few of them
were getting injured which led to the market size remaining rather small due to
the fear factor it came with. The Engineers went back to the drawing board and
quickly realised that the only way to improve this situation is to go towards
the route of using an indirect drivetrain. This allowed for the wheels to be
reduced dramatically while keeping the speed of the bike similar. And thus the “Safety
bike” was born. Needless to say the name came from the fact that how safe it
was to ride in comparison to its predecessors. The safety Bike was so popular
that to a certain extent it had managed to liberate the women of that time, as
many of them were able to, for the first time in their life travel independently

 

 

By 1885 all the major bike producers of UK had produced
safety bicycles which consisted of the diamond shape frame.

 

 

 

 

 

 

 

Diamond shape frame

This is by far the most popular design when it comes to bike
frames, the design have been serving its purpose for a very long time and it is
still recognisable from the time of its advent in 1990s when it was first
introduced for a “safety bicycle”.

The diamond shape frame gets its name due to the fake that
it has double triangles for a frame which makes it sort of look like a diamond.
As mentioned it is still recognisable which only means that the frame has been
largely left unchanged. This is due to the fact that the double triangle shape
is one the strongest shape one can form. Over the years it has proved to the
world of its great usage of material which leads to less wastage when forming
the frame, it can also take a heavy beating and still be rideable. As Paolo
explains that structurally speaking the frame is rather extraordinary he also
goes onto say when one observes engineers in their pursuit of strong structures
they tend to almost always fall back to the triangle shape and the diamond
shape frame essentially being a triple triangle structure, it’s no surprise
that it turns out to be a strong structure.

The diamond shaped frame allows for the bike to change its
configuration by altering its geometry with only a few tweaks. For example giving
the frame a relaxed angle and longer wheel base allows riders to ride their
bike for longer for comfortably while tightening up the frame geometry will
give you a road racer in essence.

Fig 4

The triangles consist of the parts below:

Head tube- It is the tube that sits at the front
of the frame and is usually of circular shape. The front fork steerer tube is
mounted within it. As can be seen from the picture below the tube has ball
bearings in-between the steerer tube in order for it to be turned and is
secured in place via the usage of Bolt, star nut or bung 

Fig 5

Top tube – This is what determines how far away
the seat tube is from the head tube. Needless to say the length the top tube
thus plays major role on the reach of the Bicycle .The length of the Top tube determines what
the bike may be used for, as an example a shorter top tube is used in conjunction
with a slightly raised head tube when it comes to cyclo sportive bike.  Fig 6

 

 

Seat tube: It connects to the other side of the
Top tube. According to bike cad “The effective seat tube length is the distance between the bottom
bracket and the point at which a virtual horizontal top tube would intersect
the seat tube.” According to this explanation, the seat tube is what keeps the
bike frames front triangle and back 2 triangles together in a single structure. Fig 7  Down tube: This is what connects the head
tube and bottom bracket and thus one can imagine the tremendous force that is
applied to this particular tube. It experiences the torsion of twisting
handlebars at its junction with the head tube and the pedalling forces at the
bottom bracket. As explained by Timothy Jon; the down tubes length is the
resultant of the designer’s decisions on the length of head tube, seat-tube and
top tube.Fig 8         Chain stays- It connects the down tube
and seat tube via the bottom bracket shell to the bottom of the seat stay via
the rear fork ends. It runs parallel to the chain and its length is measured
from the centre of the bottom bracket to the centre of the rear axle.James Olson a leading bike designer
explains in the article Buyers guide: Bicycle geometry: “The purpose of the chain
stay is to lock the rear axle in place”. Every time the rider delivers power to
the pedal of the bike, due to the force incurred the bike tries to twist the
rear axle. Again, much like the seat and head tube,
the shape and length of the chain stay wholly depends on the function the bike
plays. Fig 9   Below is a standard bicycle size geometry which
will be used later on in order to design the bike frame on CAD.

 

 Inseam
(In.)

 

Height

 

Shoe size

 

Frame size cm (c-t)

 
 

Top tube cm (c-t)

36

 

6’4”

 

11.5

 

62

 

59

35.5

 

6’2.5”

 

11

 

61

 

58

34.75

 

6’1”

 

10.5

 

60

 

57.5

34.25

 

6’0”

 

10.5

 

59

 

57

33.75

 

5’10.75”

 

10

 

58

 

56.5

33

 

5’9.5”

 

9.5

 

57

 

56

32.5

 

5’8.75”

 

9

 

56

 

55.5

32

 

5’8”

 

9

 

55

 

55

31.25

 

5’7”

 

8.5

 

54

 

54.5

30.75

 

5’6”

 

8

 

53

 

54

30

 

5’5′

 

7.5

 

52

 

53

29.5

 

5’4.5”

 

7

 

51

 

52

29

 

5’4”

 

7

 

50

 

51

28.5

 

5’3”

 

6

 

49

 

51

Fig10: Bicycle size geometry chart

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