
Bicycle Technology (1973) [pdf] - BeniBoy
http://veterancycleclublibrary.org.uk/ncl/pics/Bicycle%20Technology%20Scientific%20American%20March%201973%20(V-CC%20Library).pdf
======
forapurpose
> The thin-walled tube of circular cross section is a most efficient
> structural member; it can resist tension or compression, bending, torsion,
> or the combination of stresses that are exerted on the frame of a vehicle.
> Although for bending in a particular plane an I-section joist may be more
> efficient, if bending load can be applied in any plane, then the thin tube
> is to be preferred. It is for this reason that tubes are used as a strut or
> compression member in which failure could occur by elastic instability, or
> bowing. For torsion there is no better section, hence the tube is the
> typical main transmission shaft of an automobile. The stem of the bamboo
> plant is an excellent example of the properties of a hollow tube ...

I notice that many current bikes have flattened, non-tubular frame components.
Why? Style? New materials? I would assume, knowing little about it, that the
tube shape would generally retain its advantages regardless of the material.
But perhaps the new material doesn't form tubes well?

~~~
analog31
I think the answer is aluminum. Note that I'm not an engineer, just a
physicist. As I understand it, aluminum has different mechanical properties
such as strength to weight ratio, and how it behaves when flexed. So it may
require a different design approach to produce a strong but light frame. At
the same time, it's easy to hydroform aluminum (blow it out into a mold using
high pressure fluid), so you can in fact design a wider variety of shapes at a
tolerable cost. And if you're going to engineer the shapes of the tubes, then
why not make it look cool too.

I own one aluminum bike, relatively low end and not super lightweight... but
it does look cool. ;-)

------
avhon1
Closely related (and even briefly shown in the video) to the description of a
computer as a bicycle for the mind:
[https://www.youtube.com/watch?v=xqxWlvJ35yk](https://www.youtube.com/watch?v=xqxWlvJ35yk)

~~~
SketchySeaBeast
I don't really care for that metaphor, while it does make sense at a base
level, I feel like it doesn't quite fit. A bicycle is (once constructed)
entirely man powered - it only goes as well as we are able to power it.

The computer is more of a car for our minds - they run on electricity/gas,
take minor low effort inputs from us, and transform them into massively larger
outputs not due to simple mechanical laws, but because of a secondary source
of impetus. There isn't that 1:1 input/output that a bike has.

~~~
mrob
Not only that, but a bicycle is something that feels like part of your own
body when you're using it. If you think too hard about the positions of
everything you'll probably ride worse. A computer on the other hand is
something that requires careful thought to get the most out of it.

The real bicycle for the mind is pencil and paper.

~~~
adamc
That's a good analogy. Pencil (or pen) and paper go at human speed, like a
bicycle, and have no artificial constraints (glyphs available for writing, for
example).

I still use notebooks for some things. You can draw in a notebook (and yes, I
know you can draw on a computer, but in many ways it is more involved). The
link between thought and recording is much tighter than on a computer.

It would be interesting to look at how our tools shape and limit our thinking.

------
forapurpose
Does anyone know the source for this? I found a Scientific American article
and an Amazon listing for an out-of-print book published by Scientific
American (perhaps just a copy of the article).

[https://www.scientificamerican.com/magazine/sa/1973/03-01/#a...](https://www.scientificamerican.com/magazine/sa/1973/03-01/#article-
bicycle-technology)

[https://www.amazon.com/Bicycle-technology-S-S-
Wilson/dp/B000...](https://www.amazon.com/Bicycle-technology-S-S-
Wilson/dp/B00071F638)

EDIT: The URL includes 'Scientific American March 1973', which matches my
first link. EDIT2: So I think that must be the source.

~~~
mikestew
I don't know what you're looking for. Your own research has brought you to a
page from which you can purchase a digital copy of the whole magazine for $8.
What do you want, a printed copy?

------
fergie
Hub gears still seem like witchcraft.

~~~
denimnerd
rohloff has a 14 speed hub

~~~
13of40
I've seen those on Amazon, but it seems like they just sell the hub and brake
disc. Are you supposed to DIY the rest of the wheel or is the average bike
shop able to build it for you?

~~~
mauvehaus
In short: yes.

Slightly longer version: Find a _good_ bike shop to do it for you. The wheels
on a bicycle are about the only truly challenging thing to work on (short of
suspension components or the headset bearings that are pressed into the
frame), and about the only things that you can irretrievably screw up. A shop
that builds more than a couple wheels a year will probably do a better job
than the average bike shop.

If you're curious about what building a wheel involves, a good resource is The
Bicycle Wheel, by Jobst Brandt [0]. Mind you he still that the bottom spokes
of a wheel are in compression (which is demonstrably false; see Mavic's linear
pull spokes, which literally cannot be in compression or the wheel would fall
apart). Sheldon Brown's website is useful too.

[0][https://www.amazon.com/Bicycle-Wheel-3rd-Jobst-
Brandt/dp/096...](https://www.amazon.com/Bicycle-Wheel-3rd-Jobst-
Brandt/dp/0960723668)

~~~
garethrees
> Mind you he still that the bottom spokes of a wheel are in compression

I think you might want to read pages 7–8 again: "Wires must be tensioned to
prevent their buckling under load. With tension, wires can support compression
loads up to the point where they become slack. The same loads that increase
compression in wooden spokes, reduce tension in wires. As in algebra, where
negative and positive numbers are combined to give algebraic sums, in spokes
tension and compression are the negative and positive forces whose sums
depends on built-in spoke tension and the carried load."

So the bottom spokes can support a compressive load because this is smaller
than their unloaded tension.

~~~
mauvehaus
Yeah, I should have anticipated stirring up a debate with somebody who has
read the book more recently than 10 years ago. I should have avoided
mentioning it; the book as a whole contains a great deal of practical
information.

Anyhow, I think we are fundamentally in agreement that all of the spokes in
the wheel are in tension at all times. I am not an engineer, but I did run
this bit by an engineer. He was in agreement that the fact that the bottom
spokes are under less tension does not mean they are supporting the load via
compression.

At best, the passage is a bit misleading; none of the spokes on a bicycle
wheel are ever in compression (or as Brandt rightly claims, they would
buckle). Claiming that the reduced tension (again, correct) supports a
"compression load" is misleading.

Sorry I can't stick around for further discussion; I'll check back later.

------
forapurpose
The bicycle was, arguably, a bit too late. Imagine how cities would be
constructed today if bicycles (with modern functionality and affordability)
had predated cars by 50 years.

Imagine people trading in their horses for bicycles, for much easier care,
less pollution, much smaller and flexible (it seems to me) alternatives.
Imagine the variety of bikes people would come up with, lacking alternatives:
Personal transport, of course, but also cargo, long-haul, rough terrain,
tandem/triple/etc when more power is needed, rickshaws, etc.; with bikes
already being the established 'first mover', would we use cars for as many
purposes as we do today? Imagine how cities would be constructed, providing
for bikes first, with the car fitting in later - from roads to locations of
retail and transit.

For some things you still may have needed horses, such as pulling heavy loads.
Also, I wonder if the terrain and roads would have suited bicycles
(cobblestones and muddy roads probably aren't so great to ride on) and, if
not, if people would have invested in the infrastructure; beware the modern
myopic perspective about cities - back then almost everyone lived in rural
areas. Finally, in some less economically developed parts of the world
bicycles did become immensely popular before cars, IIRC; I wonder how these
issues played out there.

~~~
mikestew
_Imagine people trading in their horses for bicycles, for much easier care,
less pollution, much smaller and flexible (it seems to me) alternatives._

You've just copy-and-pasted Columbia's ad text from the late 1800s. The
problem was not that bicycles were too late, but that bicycles were out of
reach for the common working man for quite a while. Multi-speed, shaft-drive
bicycles with pneumatic tires were available in the 1890s. They were also
priced like Teslas.

Source: have been a member of the U. S. counterpart to the Veterans Bicycle
Club (where this article came from) since I was a kid.

~~~
bluntfang
>The problem was not that bicycles were too late, but that bicycles were out
of reach for the common working man for quite a while.

What's the difference?

~~~
mikestew
There were tons of bicycle manufacturers, so the bicycle wasn't "late", there
were plenty of them. The difference is that they were luxury items.

"The problem with the airplane was that it was late..." No, we've had
airplanes since 1903. The problem is that I can't afford, even as an upper
middle class software engineer, to keep one in the air.

