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PostPosted: Thu Dec 19, 2013 4:32 pm 
Retro Guru

Joined: Mon Feb 11, 2008 9:42 am
Posts: 2896
lewisfoto wrote:
However, to quote a local frame builder, "I would trust the fatigue life of metal over the fatigue life of plastic any day."
Well there is a fairly clear conflict of interest. Either that or he's a pillock.


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PostPosted: Thu Dec 19, 2013 4:44 pm 
rBoTM Winner
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Joined: Wed Dec 12, 2012 10:18 pm
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Location: California
mattr wrote:
lewisfoto wrote:
However, to quote a local frame builder, "I would trust the fatigue life of metal over the fatigue life of plastic any day."
Well there is a fairly clear conflict of interest. Either that or he's a pillock.



"We seldom find one wise except those of our own opinion" - Mahatma Lincoln Twain Churchill

No need to get snarky just because we disagree, besides those who market carbon, and tell you how great it is, have their own self interest in mind....


Steven


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PostPosted: Thu Dec 19, 2013 7:08 pm 
Retro Guru

Joined: Mon Feb 11, 2008 9:42 am
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Marketing? I'm more interested in materials and physics. Nevermind. Carry on.


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PostPosted: Thu Dec 19, 2013 7:14 pm 
rBoTM Winner
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mattr wrote:
Marketing? I'm more interested in materials and physics.


I keep throwing you olive branches to no avail, so go ahead state your case lets hear about this physical superiority of carbon.

Steven


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PostPosted: Thu Dec 19, 2013 7:34 pm 
Retro Guru

Joined: Mon Feb 11, 2008 9:42 am
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No, it's Ok. You and your frame builder win.


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PostPosted: Thu Dec 19, 2013 7:55 pm 
Gold Trader / MacRetro rider
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Joined: Sun May 25, 2008 11:03 am
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Location: Sunny Glasgow
mattr wrote:
lewisfoto wrote:
The problem with carbon is it can fail from a modest mark in the top layer, one the rider probably never noticed.

Steven
except that almost all carbon has a decorative protective outer layer and clear coat which provide no structural strength at all. So your "modest marks" is more likely to be "bloody great gouges and scrapes".

I'd be more worried about aluminium with "modest marks" than carbon. It's basic materials science.

I'd suspect that we don't see much failed aluminium as it gets binned long before fatigue gets hold of it. Whereas customers dropping $200+ on a carbon bar will a) want to use it for much much longer than a $50 aluminium bar. And b) rather than fitting it properly (with friction paste) will just swing on the Allen key until it stops moving. An aluminum/aluminium interface needs significantly less torque to stop slipping than carbon/aluminum or carbon/carbon. Bingo, crushed handlebars before you even get them out of the house!



Been racing yacht's for about 6 years before i got old and fat.
Delamination and osmosis :wink: Destroys eventually all carbon fiber bonded bits.


I agree with you that the 'modest' marks remark is to be frowned at but my personal opinion adds that due to the above conditions of failure a carbon fiber bond(micron thin surface coating) the constant checking would be a sensible idea. Just for safety's sake :?

It doesnt like repeated banging either by all accounts and that says to be that in bike manufacture its not something with any sort of long product life

"I would trust metal fatigue over plastic fatigue"
Wise words indeed.


PS
Carbon fiber Boat fittings are hideously expensive :wink:


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PostPosted: Thu Dec 19, 2013 11:02 pm 
Dirt Disciple

Joined: Fri Mar 09, 2012 4:31 am
Posts: 47
If I'm putting vintage bars on and plan on riding it hard my preference is Ti. I've had an old hyperlite break off on me and it wasn't pleasant, just skin loss thankfully. I was told years ago (when I started using carbon bars) to use a file and slightly round and smooth the inside edge of your stem so that the carbon isn't hitting a hard straight edge when it flexes and you will drastically reduce the chance of failure.


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PostPosted: Fri Dec 20, 2013 1:21 am 
Old School Grand Master
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Joined: Sat Jul 13, 2013 8:01 pm
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I'd be more concerned about an Alu threadless steerer, as its less likely to be inspected regularly for developing cracks, hairline fractures or otherwise. If a handlebar fails its likely to be on one side beside the stem clamp and there's more chance you will see/feel it starting to fail and act accordingly.

Interesting thread. Knowing the bars usage history is vital and personally I do prefer a bulge type rather than straight.


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PostPosted: Fri Dec 20, 2013 1:30 am 
rBoTM Winner
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The one time I did have a bar fail, it was indeed at the stem and the whole thing happened in slow motion. Unfortunately I was miles from my home in San Francisco and had to ride the bike steering and braking with one hand and holding the now separated other half in the other.


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PostPosted: Fri Dec 20, 2013 5:43 am 
Old School Grand Master
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Location: The Home Of Mountain Biking, And All Great Things.
I have heard the stronger rider is advised to restrain from gripping their Carbon bars too tightly, lest they collapse.


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