Here is a very compelling reason to chose a carbon frame:

Carbon fiber tubes have a very long fatigue life compared to aluminum and steel. It also compares favorably to titanium, but titanium is also excellent in this respect.

In other words, a carbon frame should not "wear-out" with use, wheras an aluminum frame will develope fatigue stress due to road vibration and frame flex realating to pedaling and eventually fail.

However, carbon tubes might be at higher risk of failing in a crash.

Here is a very compelling reason to chose a carbon frame:

Carbon fiber tubes have a very long fatigue life compared to aluminum and steel. It also compares favorably to titanium, but titanium is also excellent in this respect.

In other words, a carbon frame should not "wear-out" with use, wheras an aluminum frame will develope fatigue stress due to road vibration and frame flex realating to pedaling and eventually fail.

However, carbon tubes might be at higher risk of failing in a crash.

The definition of fatigue : the amplitude of variation for a number of cycles. No breaking occurs when the amplitude can be repeated for an infinite number of times.

Also, stating without a study does not an argument make:

http://www.efbe.de/etour109.htm

Just helping.

The definition of fatigue : the amplitude of variation for a number of cycles. No breaking occurs when the amplitude can be repeated for an infinite number of times.

Also, stating without a study does not an argument make:

http://www.efbe.de/etour109.htm

Just helping.
Also, such a blanket staement is nonsense. Poorly manufactured carbon fiber parts will have a shorter life. - TF

The statement should be: carbon fiber tubes CAN have a very long fatigue life. There is NOTHING to say that they will. Reinforced plastics fail in three ways - fiber breakage, fiber "pull out" and matrix failure. If you look at a broken CF part, you will see all three mechanisms, so it is hard to tell which initiated the failure. There is NO guarantee that a CF part will have better fatigue life than Al, steel, or Ti. Also, you are showing your ignorance in saying that Ti is better than steel, or comparing steel to Al. Al has a finite fatigue life - with each flex, it moves closer to failure. Steel and Ti do not have this characteristic - if you flex them at less than their fatigue limit, they essentially have an infinite fatigue life. The epoxy in a CF part is still vulnerable to ESC (environmental stress cracking) and you can flex a CF part such that the fibers break or pull out of the epoxy. Your statement is "correct within an order of magnitude" (aka wrong).

a small nick in the frame ( what would amount to a dent or divot in a Al., Ti or Steel frame)
can completely compromise a Carbon tube. If you honestly want a bike that will 'last' Steel is the choice as it will outlast any material (w/ proper rust prevention), can be repaired or even have a tube replaced. CF is a great material but it appears as if you are trying to do 'reverse science'. You have a choice and are trying to find evidence to back it and are excluding any issues that don't.

see thread: http://forums.roadbikereview.com/showthread.php?t=15840

a small nick in the frame ( what would amount to a dent or divot in a Al., Ti or Steel frame)
can completely compromise a Carbon tube. If you honestly want a bike that will 'last' Steel is the choice as it will outlast any material (w/ proper rust prevention), can be repaired or even have a tube replaced. CF is a great material but it appears as if you are trying to do 'reverse science'. You have a choice and are trying to find evidence to back it and are excluding any issues that don't.

I guess it depends on how you define "lasts." All frame materials have a finite lifespan - nothing lasts forever. A small nick in a carbon frame will not compromise it. The nick would have to be deep enough to upset the carbon fibers - and not the decorative outer layer either. If it is deep enough to do that, its a gouge. That would be more equivalent to a ding in my aluminum frame. You steel lovers are something else. ;) I'd also point out that carbon is repairable as well. You don't have to learn a technical trade like welding - you can make your own carbon fiber crap at home with a little know how and practice. The same principles apply to repairing carbon fiber.

so extrapolating all carbon frames have the characteristics of the tests on a single tube is just plain wrong. How those tubes are joined together, and joined to dropouts and bottom bracket shells are very important too (I've had failures on both those scores, give me a finely welded product any day).

I actually own more Al bikes than Steel ones and I own CF forks. Now if you read my post a say a nick that would be the equivalent to a ding in a metal frame. Contact hard enough top dent most metal tubes would be hard enough to compromise CF. Yes, you can repair, I own surfboards so I'm quite aware of 'lay-up' methods but can I see if there are micro-cracks in the inner layers? With CF you never know how bad damage is, you can only repair the surface which does little if the tube has a hairline crack all the way through.
The reason I brought up steel is not because "I'm a fanatic" but the point was fatigue life.
Now if I looked at this as a Scientist and said "which material will last longest" and added the factors of
A) fatigue life
B) repairability (Al can be fixed, rare, expensive and second welding of pipe compromises their strength, the whole reason for radically butting Al pipes is due to the 'heat damage' from welding) Steel done by Tig suffers the same compromise. CF reapirable as well, but once again no guarantee it's as good as new
C) replacability(SP), once again, bend a TT on most bikes and it's done. Steel can have a new tube dropped in easily and cheaply
D) test of time. many people are and can ride Steel Rigs that are 30-40 years old and they ride just fine. I doubt any present Al or CF rig will function very well after this time duration

so am I steel nut? no. retrogrouch, luddite? no. am I looking for an honest answer to a question. yes. will I go out and buy a steel bike? probably not, but that's because I can't afford a Sachs or Vanilla.

Does anyone else find it interesting that someone who has only made 8 posts on this board would post an opening statement like this, and then never respond to any of the comments (all of which disagree with the original post). Maybe I'm just suspiscious.

What would they be trolling for?

I doubt there are many people who will keep a bike 40 years unless you are weird in some way and never want to buy the latest and greatest... ;) :D

Many trolls are just trying to stir things up. Others are engaging in SPAM-like activities. I could be convinced that this post was either. Most likely, though, I'm just paranoid after listening to months of political attack adds from Republicans and Democrats. :)

but the arguement was on fatigue life. Lifespan of steel's proof is in the pudding. Whether you want it or not. On the other hand I don't see a huge vintage market 20 years from now with collectors buying OCLV's like guys today seek old lugged Masi's etc....