CRUM

Good point.

well biked

I've got an Easton carbon fiber flat mountain bike handlebar I've been using off road for about five years. It's the only carbon fiber part I own, and I like it. I also tried an Easton carbon fiber seatpost about five years ago, but it was extremely flexy and I returned it for a refund.

Retro Grouch 

A carbon boat that doesn't break hasn't been overbuilt, it's just been properly designed. The same is true of bike parts. At the cutting edge of design there will always be failures. That's part of the learning process. Because of this there will always be people who are afraid to try new technologies. Some bicyclists are still convinced that aluminum bike frames are ticking time bombs.

If you want the newest and lightest that's fine so long as you accept the fact that comes with increased risk of failure. If durability is a high priority, that's OK too, but it's going to weigh more.

flatlander_48

And where to ride and how often...

TomM

Like the one that crashed shortly after 9-11 because the vertical stabilizer broke off?

alanbikehouston

A properly designed, and properly built carbon fiber frame will last forever with normal use, as will a steel frame of equal quality.

The problem comes with crash impacts. Steel bends, and can be realigned. Carbon, like glass, simply shatters under impact forces that exceed design limits.

So, you want your carbon bike to last forever? Keep the rubber side down.

Bob Ross

Excellent post. (Although I'm not positive that saying carbon "simply shatters" is 100% accurate. Minor quibble.)

When I bought my first carbon frame I asked my LBS guy about all these internet horror stories I'd read. He asked "how often have you crashed on your current bike?" (answer: almost never) followed by "Do you plan on crashing any more frequently with this new bike?"

aaronspoker

I do not beleive this is accurate. While carbon can definitely fail catastrophically at crashes, I do not beleive this is the primary durability issue.

The main issue is fatigue life. Light carbon fiber load-bearing components have a low fatigue life due to the properties of carbon composites. While carbon fiber components can be built to have a very long fatigue life (perhaps this is what you mean by "properly designed"), generally this will defeat the benefits of carbon fiber: weight and damping. As an example, a carbon fiber seatpost that will last as long as an aluminum one will be significantly heavier.

Interestingly, the most effective way of mitigating the fragility of carbon fiber is to combine it with a more durable material, such as aluminum--but this also will tend to undermine the advantages of carbon.

Carbon is also extremely sensitive to superficial scratches and other crack nucleation points; all materials are to some degree, but carbon composites are usually much more so.

I'd welcome evidence to the contrary, but my present understanding of the present technology is that all light weight pure carbon tube frames will fail after a relatively short fatigue life, most likely around the joint bonds. Composite technology is advancing very rapidly, but I think we have a ways to go before carbon will match the resiliancy of aluminum or steel.

TomM

So what's the fatigue life of a carbon road frame?

well biked

I dunno about that, at least when it comes to handlebars. Easton's SLX carbon fiber drop bars(claimed weight of 200grams) are advertised as having "unlimited fatigue life." I'm not saying you couldn't break them, but if you're talking about fatigue life, I think there's a good chance they're pretty darned good, much better than aluminum. And they're lighter, too-

alanbikehouston

The first company to build carbon fiber bikes in large numbers in the USA was Trek. Their engineers are confident that their carbon tubes will last essentially "forever" under the normal, routine stresses of riding a bike.

And, with all the stories about carbon frames that failed because of improper joining of the tube (a 1988ish problem) or from severe crash impact damage, there has yet to be a credible, documented report of a "name brand" carbon frame having a tube fail simply because of "X" numbers of cycles of routine stress.

And, the same is true of properly designed and constructed steel frames and forks. If a bike with a Reynolds 531 frame fails, it will be where the chainstay is attached to the bottom bracket, not in the center of the tube.

Trek, and some other top companies have crash replacement policies that make it a bit less painful to replace a frame that was trashed in a crash, so that sort of event should "sting" a bit less.

Old School

These are very general statements that beg to be challenged. Many of us who ride CF will never race. I hardly consider my Trek OCLV frame "disposable" (maybe if I was a sponsored professional racer, but...). I know plenty of people who have ridden their CF frame a lot longer than five years. Where do you get your facts??

Old School

I have to agree. Just remember, an impact great enough to "shatter" CF will likely do significant irreparable damage to a steel frame as well.

Cyclist0383

Mostly from the bike shop I spend time in. True, it's a shop that mostly caters to pros and serious racers, but the general wisdom there is that CF isn't a long term purchase.

rockabilly808

If that was how the statement was taken I think I should clarify what I meant. What I meant is that builders are trying to make the boats lighter and aren't bulking up certian high stress that need mroe material, the builders think "oh carbon is stronger so I don't need to use as much as building with fiberglass" so they underbuld the structure and where as fiberglass would ahve flexed a bit and keep on fine the carbon structure due to the bittle nature of carbon breaks. Not related to cycling but just wanted to clarify my statement.

TomM

To be honest, that sounds like normal bike shop gibberish where they want you to buy the latest/greatest bike.

brian416

The mountain bike I ride is a 10 year old Trek, the carbon fiber frame is holding up just fine

Cyclist0383

Actually no. It's more of a high end workshop than a regular bike shop. It's run by a former pro team wrench who is now the national team's head wrench. They have always done right by me as far as not trying to sell me something I don't want or need, and provide the excellent service. Once he opened up on a Sunday morning for me, once he came in at 5:00 am so I could have my bike by 9:00.

Anyplace where I can pick up a slightly used Colnago Master for a little over $200 isn't your typical rip-off shop. I think he's just seen a lot of broken CF over the years.

Blue Jays

What brand of bicycles is the Latvian National Cycling Team using these days? Which material?

Cyclist0383

I don't know what the national team is currently using, but one of the local pro teams is riding top of the line giants, which of course are CF, and which of course are replaced regularly.

hairytoes

The problems with CF bikes aren't usually to do with the carbon bit at all, but the resin. There will be different qualities of this from different manufacturers. The carbon fibres prob do have an infinite fatigue lifespan. Steel is pretty high. Al is low.

If you have a crash and crush some of the resin, it is permanently damaged. Very thin tubes of CF+resin might flex without damage to the resin.

I used to race kayaks. One boat I had was built by a small kayak manufacturer, for the manufacturer's son. No expense spared on the materials; so they used the highest grade epoxy available. Most kayaks were built with polyester back then. (this was a flat water kayak, 17'6" long, weighing less than 20lb)

I hit a rock . The only damage was a minute chip.

My other boat, weighing twice as much, would have holed in the same situation.

I'm betting it's the same with CF. Very high-end bikes will last longer.

flatlander_48

Calfee Design...
Calfee Design warrants to the original registered owner that its products are free of manufacturer's defects for a period of 25 years for the Tetra and Dragonfly and 10 years for the Luna and Bamboo from the original date of purchase.

Shavit

Quote from Nikephorus:
"I think people are too busy arguing materials when they should be arguing workmanship."

I agree with Crum ... this is an excellent point.

I will say to the OP, that while I am generally ignorant on the subject, my fear/mistrust of Carbon Fiber frames comes from my inability to fix them, or have others fix them at a reasonable price. Warranties aside, i haven't been too impressed with the stories friends have told ...

(and for me, the frame will eventually take some sort of hit, be it from a car, a wreck, tripping on the steps while carrying it, etc. It's only a matter of time before i'm trying to work out a dent)

czrich86

Hi everyone, this is my first post. I am currently looking around for a new road bike. I've been riding a Centurian Le Mans steel road frame from probably the late 70's or early 80's. I came across a carbon bike with aluminum lugs in a LBS, it's the NX7 from Blue Competition Cycles. It was really light and felt really good sitting on it. I couldn't test ride though, so I'm not sure how it rides. How would this sort of design, with the aluminum lugs and CF frame, affect the bike/ride/anything else? Carbon seems like a great new material to use, but after reading a lot of your posts, I wonder if I should I stay away from carbon all together?
I keep hearing so much from people about how CF is so easily broken from a tiny scratch and how steel bikes are the way to go and blah blah blah. There just seems to be so much propaganda either way that it's making my head spin. Does it really only take a little scratch to kill carbon? Is there no protective paint or anything to help prevent this? Does anyone know of any reviews or trials of NX7? Any objective info would help a lot, thanks guys.

rockabilly808

well not a tiny scratch, hell a lot of carbon components have a gel coat on em and that can literally be chiped away bit my bit and as long as there are so considerableimpacts the carbon structure uder the gelcoat can be perfectly sound