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PostPosted: Sat Nov 10, 2007 7:26 pm 
Old School Grand Master
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Joined: Tue Jul 05, 2005 3:14 pm
Posts: 13411
Location: Warwick
But point made earlier - the real world application of all those materials when used in a bike frame is another thing altogether.

A materials tensile strength, the way its formed, welded etc to make a form thats super strong in certain forces and situations.

I remember a bike shop showing me a seattube of an Adroit - a decal it said "Under no circumstances do not clamp in a bike stand at this point" (or something along those lines)

It was so thin at that area you could crumple it using your bare hands. :shock:


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PostPosted: Sat Nov 10, 2007 7:37 pm 
retrobike rider
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Joined: Sun Sep 23, 2007 11:22 pm
Posts: 7306
Location: Hove
great vid, but people are always saying 'titanium is stronger' or whatever, but surely any metal is strong, but what we're interested in isn't strength as an absolute but the strength:weight ratio? How much weight of each metal do you need in order to have the required strength?

Interesting in relation to this video that Carl Strong says 953 is so strong in relation to weight that you could build a bike frame out of such thin tubes that in his view it's unsuitable for mtb. i.e., at the optimum weight the frame would be strong enough for mtb stresses, but the tubing would be so thin that it would be excessively prone to dents.

Well I think it's interesting anyway - just proves I'm even sadder than you Russ!

[edit - hadn't seen Jez's post - great minds think alike?]


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PostPosted: Sat Nov 10, 2007 10:23 pm 
Gold Trader
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Joined: Sat Jul 29, 2006 11:14 pm
Posts: 3879
Location: Somerset
Russell wrote:
I'm a CNC Machine Engineer. People give me drawings of little metal parts and I go away for a couple of days and get back to them with little metal parts. Mostly development and small batch stuff. I work here in fact...

http://www.genhart.co.uk/default.htm


Can I send you a Pace seat clamp to copy? :wink:


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PostPosted: Sat Nov 10, 2007 10:27 pm 
Retro Guru
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Joined: Sat Mar 10, 2007 11:46 am
Posts: 389
I just started working for a company that makes testing equipment. Tear apart materials, twist them, suspension simulator for cars, APC's, motorcycles, earthquake simulators, tire testers, you name it, they either make it or could make it. You need to stretch the fibers of a mouse's uterus to see how contraceptives affect them? Been there, done that. I know this video is a couple of yokels goofing around but it really is surprising how sophisticated the testing regimens are. Carefully thought up and very detailed measurement taken. Lots of data to be crunched.

They would be able to put such a simple test as show in the video to shame. So if anyone wants any frames tested, be sure to send two of them along. One can be put into destructive testing and torn to shreds and the other will be kept as a "control".

Pinguwin


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PostPosted: Sat Nov 10, 2007 10:31 pm 
Gold Trader
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Location: Somerset
The thing is though, Carbon is only strong in the direction that the weave is designed to be loaded.

Helicopter rotor blades are a good example, snap them in one direction yet the will hold tonnes of force in other directions.

An amusing but hardly scientific test, a kind of metallurgists witch trial. :wink:


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PostPosted: Sat Nov 10, 2007 10:51 pm 
King of the DuckBoard
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Joined: Sun Jan 28, 2007 12:30 pm
Posts: 21466
Good fun. but why no steel tube??

:D


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PostPosted: Sat Nov 10, 2007 11:04 pm 
Retro Guru
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Joined: Sat Mar 10, 2007 11:46 am
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tintin40 wrote:
but why no steel tube??


Cause it will do the same as the Ti tube at 1/3rd the cost? 0.50 :D


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PostPosted: Sat Nov 10, 2007 11:19 pm 
Dirt Disciple

Joined: Sun Sep 16, 2007 6:02 pm
Posts: 31
Location: devon
Ti should be that good considering how much it cost


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PostPosted: Sat Nov 10, 2007 11:27 pm 
Retro Guru
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Joined: Mon Jul 31, 2006 3:07 pm
Posts: 2044
My Y-bb was once backed over by my my good friend and they both survived. The Moots had at the time an EC-carbon bar that wedged between the rear bumper and the ground. It dug in and just dragged everything with it. Nothing on the bike broke and I rode it that day.
My friends bumper had a 10-12 in dent.
The bar stem and bike are still being used today.
Also I shortened that bar by about 1in at each end. I took each of those pieces and smashed them with a 2 lb hammer just to see what would happen...and nothing happened. The hammer bounced off over and over. The vid is NOT what I have seen and experienced with my own eyes.
I am not a carbon sales guy...just a guy.


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PostPosted: Sun Nov 11, 2007 2:25 am 
Gold Trader
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Joined: Wed Jun 20, 2007 11:19 pm
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Location: Odense, Denmark
Last place I worked, we had a couple of Scott CR1s that had been written off at high speed.

The weak link was the head-tube/top tube join.

Anyway, for fun we chopped up one of the frames and put the various tubes in the vice....

Sure, they splintered. But they remained tube-like. Even with 2 of us hanging off the vice handle we could not get the tubing to fail in such a way that it would be dangerous.

We did similar "tests" on offcuts from carbon fork steerers, with similar results....

I'm happy with my carbon road bike.... If ever it gets subjected to greater forces than it can take, I'll probably be too deceased or permanently handicapped to care....


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