carbonfiber unicycle frames?

GizmoDuck said:

I have seen a carbon Muni (one of the first made belonging to Jez
Weston). It's still one of the lightest Muni's I've picked up.

Yeah, the carbon munis Roger made are light. But mainly because he used
super lightweight parts for other parts of them than the frame. For
example, they run a 2" tyre, a narrow rim, a non-splined hub, a
lightweight inner tube, a lightweight seatpost, a miyata seat with a
carbon base, magnesium lightweight pedals. Those things make way more
difference than the 200g or whatever it is saved on the frame.

Joe

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joemarshall said:

Yeah, the carbon munis Roger made are light. But mainly because he used
super lightweight parts for other parts of them than the frame. For
example, they run a 2" tyre, a narrow rim, a non-splined hub, a
lightweight inner tube, a lightweight seatpost, a miyata seat with a
carbon base, magnesium lightweight pedals.

Before you youngsters start getting the wrong idea, remember those parts
were chosen not purely for their weight, but because they were the
top-of-the-line stuff available then, for their weight. There were no
splined hubs, Miyata made the best seats, etc. The biggest drawback of
my Roger Davies frame is the measurement between the fork legs. Fat
tires don't fit! Nobody was using them at the time, either. So my
carbon MUni, with 26" wheel, remains one of the lightest unicycles in
my collection.

There was a Japanese guy with a gorgeous, monocoque carbon unicycle at
Unicon IX in Germany. The thing was gorgeous; a work of art. Aluminum
seat post, handmade bearing holders and cranks, and a carbon hub. The
crown and legs had a cross-section like an airplane wing. Sweet!
Someday I'll have to scan those pictures...

So Tour de France riders all have carbon. What's that got to do with
us? Though a few of us have unlimited budgets, there still needs to be
a market for someone to produce anything in decent enough amounts for
it not to be astronomically expensive. That's what I meant earlier. The
guy with the carbon uni at Unicon IX told me it cost him roughly the
equivalent of a "small car" in his limited English.

--
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John Foss
Email: "jfoss" at "unicycling.com" -- www.unicycling.com
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joemarshall said:

Yeah, the carbon munis Roger made are light.

Joe

No, I think Jez beat him to it with the first Carbon Uni. Although
Roger went on to make a production version.

John, I was referring to your reference about bikes. Most of the top
end bikes are carbon. They are getting cheaper and quite a few
mid-range bikes are carbon also.

I wouldn't mind spending a bit more on a unicycle. Unicycles are cheap
compared to a bikes. I spent more in one year racing bikes than I have
in 7yrs unicycling.

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The Uninam Tour 2008.....Hanoi to Saigon!!! www.uninam.net

The Monguni 2009....Unicycle Tour of Mongolia

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skrobo said:

not so much for a unicycle frame.
it shouldn't be more than $50 in carbon fiber.
that is about how much it is to do a skimboard, so i'm guessing its
much cheaper than that.

EDIT: building it would defiinitely be a MAJOR pain though...

Well, in materials, cf isn't extremely expensive, but forming it into
the proper shapes that will give a signifficant weight advantage and
still be strong is a very long and expensive design process. Also
someone who shells out such a large sum of cash for a frame would also
likely expect it to be at least as strong as any frame out there, uping
the R&D costs more. Another thing is cf has poor resistance to
repeated stress, worse than aluminum, and as someone said breaks before
bending and all the UPD's would wear it out as well.

Not that it can't or shouldn't be done. It'd be cool to see a well
made cf uni and how it compared to other frames.

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Ride everywhere and never just ride anywhere. If you can ride where you
are going within a hour, do it, and if you can do a trick 50-75% of the
time do it along the way.
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Im jw, how does the weight of aluminum, titanium, and carbon fiber
compare?

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Material Density (g/cm^3) Stiffness (GPa) Ratio
4130 Steel 7.85 205 26.11464968
Titanium 4.506 116 25.74345317
Aluminum 2.7 70 25.92592593
CF 1.75 150 85.71428571

Ok, ok. I know you asked for the weight, but I figure what you -really-
wanted was the density, since you didn't specify an amount of each to
give you the weight for 😉

However, keep in mind that the structure of the frame contributes as
much or more to the weight of the frame than the density alone. For
example, steel is quite stiff, stiffer than either aluminum or
titanium, so you can use less material to make a frame of similar
stiffness, while it takes something like twice the amount of aluminum
to make a frame of similar stiffness.

What we should define for these framebuilding questions is a density to
stiffness ratio. On this basis, CF is best, followed by steel, then
alu, then titanium. Factoring in strength makes it more difficult,
because that varies with strength treating and alloying process, as
well as with the amount of material used.

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dman1234 said:

I think carbon fiber is the way to go, it's an amazing material. By
weight it's much stronger and stiffer than steel, aluminum and even
titanium.

You sure, because I'm not 😕

oh handy table:
Material Density (g/cm^3) Stiffness (GPa) Ratio
4130 Steel 7.85 205 26.11464968
Titanium 4.506 116 25.74345317
Aluminum 2.7 70 25.92592593
CF 1.75 150 85.71428571

--
thejdw

kington99 said:

A hobnob is an oaty biscuit, the fact that they don't exist in america
just goes to show that you have no culinary heritage 🙂

Quoted message said:

Quoted message said:

don't follow Jesus, follow me!<<

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dman1234 said:

By weight it's much stronger and stiffer than steel aluminum and even
titanium.

haha...I missed this at first. CF is stronger than -*even*- titanium?
Wow...titanium must be a cool space-agey metal...so it must be good.

Wait...steel is stronger and stiffer than titanium too...🙄

Oh, and I don't know why we're dealing with hollow tubes. We should
make some internally trussed tubes to make super-ultra-rigid frames,
then we can make them out of aluminum foil!!!!1!!

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Catching the coker fever.
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onelesscar said:

haha...I missed this at first. CF is stronger than -*even*- titanium?
Wow...titanium must be a cool space-agey metal...so it must be good.

Wait...steel is stronger and stiffer than titanium too...🙄

Oh, and I don't know why we're dealing with hollow tubes. We should
make some internally trussed tubes to make super-ultra-rigid frames,
then we can make them out of aluminum foil!!!!1!!

A frame of aluminium foil would be like a seat post made of play- doe

--
thejdw

kington99 said:

A hobnob is an oaty biscuit, the fact that they don't exist in america
just goes to show that you have no culinary heritage 🙂

Quoted message said:

Quoted message said:

don't follow Jesus, follow me!<<

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onelesscar said:

Oh, and I don't know why we're dealing with hollow tubes. We should
make some internally trussed tubes to make super-ultra-rigid frames,
then we can make them out of aluminum foil!!!!1!!

Koxx have already thought of that;
http://tinyurl.com/yt9nkf

😄

STM

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semach.the.monkey said:

Koxx have already thought of that;
http://tinyurl.com/yt9nkf

😄

STM

haha some of the people were like "is that a freestyle frame?" and
didnt get it was a joke.

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still be ugly.
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onelesscar said:

Material Density (g/cm^3) Stiffness (GPa) Ratio
4130 Steel 7.85 205 26.11464968
Titanium 4.506 116 25.74345317
Aluminum 2.7 70 25.92592593
CF 1.75 150 85.71428571

Ok, ok. I know you asked for the weight, but I figure what you -really-
wanted was the density, since you didn't specify an amount of each to
give you the weight for 😉

However, keep in mind that the structure of the frame contributes as
much or more to the weight of the frame than the density alone. For
example, steel is quite stiff, stiffer than either aluminum or
titanium, so you can use less material to make a frame of similar
stiffness, while it takes something like twice the amount of aluminum
to make a frame of similar stiffness.

What we should define for these framebuilding questions is a density to
stiffness ratio. On this basis, CF is best, followed by steel, then
alu, then titanium. Factoring in strength makes it more difficult,
because that varies with strength treating and alloying process, as
well as with the amount of material used.

Thanx that was helpful. yea i did mean density.

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dman1234 said:

I think carbon fiber is the way to go, it's an amazing material. By
weight it's much stronger and stiffer than steel aluminum and even
titanium.

The reason that their are so few carbon fiber bikes is simply because
they cost a lot, the demand isn't there.

I think it would be ideal for coker and muni frames.

-'great video about CF bikes ' (http://tinyurl.com/3apetg)

in all due respect, hahahaha

I could a smash a pure cf muni frame in one ride.

the first time it rolled down a long rocky slope it would snap.

it would have to be solid carbon fiber, witch would cost a crapload of
money.

the main reason is because CF is so brittle. as soon as it passes its
stress limit its over.

edit: Im sorry if that turned out meaner sounding than I meant...

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aim:kiloornish
email: mornish AT gmail DOT com

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mornish said:

the first time it rolled down a long rocky slope it would snap.
[...]
the main reason is because CF is so brittle. as soon as it passes its
stress limit its over.

Oh, really? You know this from experience?

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Quoted message said:

Originally Posted by mornish
the first time it rolled down a long rocky slope it would snap.
[...]
the main reason is because CF is so brittle. as soon as it passes its
stress limit its over.

yeah duhh thats why the big 5 monutionbike manufactures are all turning
to it now. It clearly sucks

--
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www.unicyclepa.com
we suck
but its all good
team YAMS member in your sig or title and say
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Quoted message said:

Originally Posted by mornish
the first time it rolled down a long rocky slope it would snap.
[...]
the main reason is because CF is so brittle. as soon as it passes its
stress limit its over.

yeah duhh thats why the big 5 monutionbike manufactures are all turning
to it now. It clearly sucks

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www.unicyclepa.com
we suck
but its all good
team YAMS member in your sig or title and say
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i do not belive that Carbon Fibre will make a good uni frame. uni
frames have more twisty(very official word, right😉) forces applied to
them that, say a bike fork.
J'ust because carbon fiber has a great strength advantage over stee'
(http://tinyurl.com/3dwer8)l does not mean that it is a better
material.

urlhttp://en.wikipedia.org/wiki/Tensile_strength#Concept/url said:

Brittle materials such as concrete and carbon fiber do not have a yield
point, and do not strain-harden which means that the ultimate strength
and breaking strength are the same. A most unusual stress-strain curve
is shown in the figure below. Typical brittle materials do not show any
plastic deformation but fail while the deformation is elastic. One of
the characteristics of a brittle failure is that the two broken parts
can be reassembled to produce the same shape as the original component.
A typical stress strain curve for a brittle material will be linear.
Testing of several identical specimens will result in different failure
stresses. The curve shown below would be typical of a brittle polymer
tested at very slow strain rates at a temperature above its glass
transition temperature. Some engineering ceramics show a small amount
of ductile behavior at stresses just below that causing failure but the
initial part of the curve is a linear.

Steel can withstand much more elastic deformation than CF can due to
its lower tensile strength, but because of the nature of CF, it will
just shatter.

--
Det-riot

Jerrick said:

I think we should get off the topic off kinky/horny girls and unicycles,
and back to creepy horny men.

KOXX-ONE* DOES NOT* SUCK!!!!
'MRIS!!!!' (http://tinyurl.com/2486qk)
'1000th Post' (http://tinyurl.com/33shzt)
_*UNICYCLE_FOR_DONUTS!!!!*_
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Det-riot said:

i do not belive that Carbon Fibre will make a good uni frame. uni
frames have more twisty(very official word, right😉) forces applied to
them that, say a bike fork.
J'ust because carbon fiber has a great strength advantage over stee'
(http://tinyurl.com/3dwer8)l does not mean that it is a better
material.

Steel can withstand much more elastic deformation than CF can due to
its lower tensile strength, but because of the nature of CF, it will
just shatter.

It dossen't say what type of steel it is, a diffrent alloy may be
stronger.

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kington99 said:

A hobnob is an oaty biscuit, the fact that they don't exist in america
just goes to show that you have no culinary heritage 🙂

Quoted message said:

Quoted message said:

don't follow Jesus, follow me!<<

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thejdw said:

It dossen't say what type of steel it is, a diffrent alloy may be
stronger.

i know, i was using that to show how strong CF was in some aspects.

--
Det-riot

Jerrick said:

I think we should get off the topic off kinky/horny girls and unicycles,
and back to creepy horny men.

KOXX-ONE* DOES NOT* SUCK!!!!
'MRIS!!!!' (http://tinyurl.com/2486qk)
'1000th Post' (http://tinyurl.com/33shzt)
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mornish said:

it would have to be solid carbon fiber

Sounds like someone's confused about CF...

'Carbon fiber ' (http://en.wikipedia.org/wiki/Carbon_fiber)is just what
its name implies... it's a fiber, thinner than a human hair. Like
fiberglass, carbon fiber is woven into a lattice-like fabric which is
then formed and set into plastic. This material is then called 'carbon
fiber reinforced plastic' (http://tinyurl.com/2zfuxx).

Note: this material isn't "solid CF" it's merely plastic with embedded
CF fibers.

As I've pointed out many times before on these fora, CF's strength
exists only along the length of the fibers. In a fork or a uni frame,
the fibers run the length of the legs, to support the weight of the
rider. Any impacts on that frame would apply force along the sides of
the fibers, where they are the weakest... and this is why a CF uni
frame must be handled with care.

Quoted message said:

witch would cost a crapload of money

I've never bought 'a witch'
(http://www.megomuseum.com/woz/images/WitchHeader.jpg) before but I've
seen witch costumes for sale for about the price of a pair of pedals.

--
maestro8

Those are my principles. If you don't like those, I have others. --
Groucho Marx

The only way to comprehend what mathematicians mean by Infinity is to
contemplate the extent of human stupidity. -- François-Marie Arouet de
Voltaire
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