I thought CF was used in applications where the strength to weight balance justified the high cost. I can't see that as being true in bridge girders.

http://3.bp.blogspot.com/-F8Rk1H_fr9...%2Bcrabon.jpeg

Joe Moses snapped steerer during Three Peaks Cyclo Cross - Cycling Weekly

Good, documented example. I would observe that the site of the failure is subject to user error in the form of overtightening the stem bolts. Would steel have failed? Nope. Could the failure of CF have been prevented by rigorous attention to detail. Dunno. Maybe.

OP you might find this recent NYTimes article on plastic bikes interesting. I found it a good read, being fair, objective, and hitting the nail on the head.

Despite those qualities, many members of this forum reacted quite vigorously - in fact, explosively - in disagreement at the time of the release. Apparently their own professional expertise, gleamed from magazine articles and ads, exceeds that of the experts the author cited for his article. To each his own. :rolleyes:

At any rate, OP, I would invite you to give the article a good read and decide for yourself. Personally, I prefer to put my faith in industry experts rather than Bike Forum, um, "experts".

Imagine replacing your crabon BMX frame after every heat...

http://www.bmxinternational.com.au/U...87A871506A.jpg

...this is a point I have attempted to make with my fellows here in Sacramento with little success.

I have seen horrible things done in the name of bicycle maintenance and mechanics, some of it done by people who profess
to know about such things, and even some by people who are paid to know about such things.

So while I am the first to concede that a very lightweight, responsive, laterally stiff and vertically compliant bicycle cycle can
be manufactured from CF composites, and ridden fast and furious for many miles of Cat 6 ecstasy, the odds are pretty good, I think,
that as such bikes age, get resold, and worked on by the usual idiots who have done a certain procedure the same way their entire
lives, they are gonna start asploding.

Compared to the automotive mechanical trades, or the aerospace mechanical trades, bicycle repair and maintenance personnel are
little certified, if at all, and poorly paid in most instances. Thus I have no problem at all in saying that there will be increasing numbers
of horrific crashes attributed to CF bike structural failures.......many of them probably from just such over torquing as you describe.

But I digress...................

..........so hurtful.http://board.whatisfatmagulsfault.co...ult/crying.gif

Though I'm not a fan of carbon for a number of reasons, I don't believe that it degrades much over time, except maybe from numerous crashes.

However, unlike metal, CF doesn't usually announce an issue or severe crash by bending, so the owner has no obvious gauge to go by. Also keep in mind that old carbon isn't just older, it's also farther back on the learning curve. It took some time to learn to work smart with CF, and if the bike is old, there's a risk that it predates some improvements.

None, but ask Boeing.....that giant plane you ride is made from it

Read that article linked by BillyD in post #30 . The airline manufacturing industry and the bicycle industry's approach to the use of carbon are diametrically opposite. Granted, that a cornerstone principle in aviation design is redundancy, still, I am of the view that carbon frames are getting ridiculously light. Of course that could be because I am 200Ibs.

You should try actually reading that article sometime.

I'd look for the pavement. It'll be coming up fast.

This is the argument that kept me from buying an "old" carbon bike or frame. Not the age of the CF but the techniques and blends that were used on earlier bike compared to current bikes.

Only airplanes.

There is environmental and chemical degradation, however less than steel. The degradation is confined to the top surface of the laminate structure, having limited influence on the mechanical behavior.

[MENTION=29415]BillyD[/MENTION] is trolling. What's your excuse?

...everybody likes to use the airplane comparison.

So what happens if you give a carbon fiber airplane to somebody and they take it to your LBS for servicing ?
Also, do you have the maintenance schedule and safety check inspection reports for your Specialized Tarmac ?

I was thinking the same thing. Why would there be an advantage to using carbon fiber girders?

He chooses not to drink the koolaid, what's your excuse?

This is a free world, anybody can buy whatever they like. Nobody is trying to stop you. The article speaks for itself, loud and clear.

Believe what you want, I'll be damned if BillyD is going to argue about it. :lol:

There would be a tremendous advantage. The primary limiter of span length is the dead weight of the structure. If you could maintain strength while keeping weight down bridges could have longer unsupported spans. The centuries old progress in bridge spans owes more to improvements in available materials than any other factor. CF may be the next logical step in that progression.

CF is relatively new, and unfortunately, in the bicycle world is used to build race bike clones. However if those same materials were used from design forward to build bikes best suited for touring or commuting, you'd see bikes a bit heavy by CF standards, but lighter and stronger than the steel bikes they replace.

The issues with CF aren't the CF, but how the builders use it.

Sure, but aircraft have legally mandated airframe inspections to detect problems.

Correct.

If you're reading it for confirmation of preconceived notions, it speaks to that loud and clear. Unfortunately, if you read it objectively, it says something else. No one expects that you have that desire and/or capability to do that, though. ;)

Look, carbon fiber bicycle frames in an undamaged state are enormously strong. Carbon fiber does not, for practical purposes, become damaged by time or by normal use. So an old carbon fiber frame is not automatically unsafe.

The catch is that damaged carbon fiber bicycle frames can be very weak, and that damage to carbon fiber is not always visible, even to close visual inspection. Those carbon fiber aircraft parts everyone likes to refer to undergo regular, advanced inspections with things like ultrasound. Also, carbon fiber aircraft are not routinely dropped or crashed and then sold on Craigslist to people who won't have the slightest idea about their history.

If you buy a new carbon frame from a reputable seller you are almost guaranteed a safe, strong bicycle. If you avoid crashing it, abusing it, and banging it around in general, it should remain safe and strong for as long as you own it. But unless you know for an absolute fact that the used carbon frame you are looking at has a similar history, then you are really just rolling the dice. It's a roll that usually comes out just fine, but a roll nonetheless. I personally wouldn't ride a used carbon bike if I wasn't absolutely sure of its history - or managed to get Boeing to put it through a comprehensive inspection.

The only way that article makes any sense is if you are so desperate to have it reinforce your agenda that you suspend your ability to think critically. It's been debunked multiple times by others and by me here and other places.