Oh Snap... [Video]
#26
Senior Member
Joined: Jun 2007
Posts: 12,257
Likes: 5
From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
There's a difference between hits and compression.
steel sucks in compression and will buckle or squish if it's loaded up too much.
There's a reason why spokes are made from steel and it's because steel is a great material under tension.
carbon also sucks in compression, but it is stronger under certain directions of compressive forces. straight down the tube is good, but not so much against clamping forces.
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Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Last edited by AEO; 06-29-10 at 07:09 AM.
#27
Veteran Racer


Joined: Jul 2009
Posts: 11,854
Likes: 913
From: Ciudad de Vacas, Tejas
Bikes: 34 frames + 80 wheels
The nonsense factor here is astounding. Please do some research on materials and mechanics before posting.
#28

Rebecca Twiggs Titanium MERLIN just sold for 400 on Ebay!!
It was my size too!!!

https://cgi.ebay.com/ws/eBayISAPI.dll...m=130402783337
Rebecca racing on the actual MERLIN shown above:
https://www.procyclingwomen.com/Twigg.wmv
Last edited by MysticRats; 06-29-10 at 08:04 AM.
#29
Veteran Racer


Joined: Jul 2009
Posts: 11,854
Likes: 913
From: Ciudad de Vacas, Tejas
Bikes: 34 frames + 80 wheels
But did you notice the female specific geometry for long legs and short torso? The ST is 51cm c-t but the TT is only 49cm. This is just the opposite from the proportions for a typical male. Now, if those specs were reversed, I'd have been all over it.
#30
Senior Member
Joined: Jun 2007
Posts: 12,257
Likes: 5
From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
you know, realistically, on a 700c wheel bike, the TT never gets shorter than 21" when you add up all the numbers.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
#31
Senior Member
Joined: Jun 2007
Posts: 12,257
Likes: 5
From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
concrete holds buildings up in compression.
steel bars act under tension to keep the concrete in its place when the building sways.
that's why you can hang off a 14ga spoke, but squish it with the same weight.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
#32
Veteran Racer


Joined: Jul 2009
Posts: 11,854
Likes: 913
From: Ciudad de Vacas, Tejas
Bikes: 34 frames + 80 wheels
As I said, this is nonsense. The compressive strength of steel as a material is exactly the same as its tensile strength. A steel spoke is a slender column, which buckles under compression and the material itself remains elastic. The only material parameter that is pertinent in (Euler) buckling is the elastic modulus, however, the geometry of the cross-section of the structural member plays a far greater part in determining it's capacity. Same for any other other material; there is no "squishing" involved (the proper technical term is yielding). The suitability of a particular material for use as a structural element in a particular application is determined by many factors, including ability to form and shape, ability to be joined at connections, ability to be manufactured with consistency and reliability.
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What, Me Worry? - Alfred E. Neuman
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What, Me Worry? - Alfred E. Neuman
I see the light at the end of the tunnel, but the tunnel keeps getting longer - me
Last edited by TejanoTrackie; 06-29-10 at 10:08 AM.
#33
It's kinda interesting that that ladies' frame fractured at the center. I think that frame is weak if the direction of impact (or any other type of stresses) is misaligned with frame's own orientation. (Prolly, straight pull) Also, I am thinking it is prolly weak to compression at the center where it's probably thinned to save weight and all. (Maybe it's designed to crumple like that to so debris become small quick and impact people at less force.)
I think the demo with the MTB racing carbon fork is a little different. I am pretty sure that fork is designed to take misaligned stresses which you face in trails. So if you do that on that lady's carbon track frame at the down tube center, it will probably snap.
Speaking of B*C frames, you see those tubes don't have circular cross-section. I think it's 4 wedged star-like. I bet impact stresses would focus on the wedges. I thought they were doing that to stiffen the frame. ... Give and take huh? But then I saw a guy tricking on a B*C frame before. ... Anyone know about that?
Darn you won't need to answer that. I won't be able to afford a carbon track frame anyway.
I think the demo with the MTB racing carbon fork is a little different. I am pretty sure that fork is designed to take misaligned stresses which you face in trails. So if you do that on that lady's carbon track frame at the down tube center, it will probably snap.
Speaking of B*C frames, you see those tubes don't have circular cross-section. I think it's 4 wedged star-like. I bet impact stresses would focus on the wedges. I thought they were doing that to stiffen the frame. ... Give and take huh? But then I saw a guy tricking on a B*C frame before. ... Anyone know about that?
Darn you won't need to answer that. I won't be able to afford a carbon track frame anyway.
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