WalksOn2Wheels

Hi all, new to the board. Yet another place to waste time online....

Anyhow, I've been putting the miles on my entry level aluminum frame and was looking to upgrade over the winter. I got a lead on a fella that has some carbon road bike frames that are doing him no good sitting in a warehouse. Now before I even call and ask what exactly he has as far as brands, sizes, etc. I would like to know just what ages a carbon frame?

Obviously if the frame has some miles on it, it stresses the carbon over time and that ages the frame. Also, UV damage on unpainted carbon, etc. But if it's been in a warehouse, will heat and humidity age it just as quickly?

Any information/links to online articles would be appreciated.

tkm

One of the benefits of carbon is that it doesn't fatigue, unlike aluminum. I'm not sure where you're getting the above idea from.

bobthib

I live in So Fla and this is my concern. I tell my wife I have to keep my carbon bike in the house due to the heat and humidity in the garage in the summer.

coasting 

does clearcoat protect from uv?

BananaTugger

On newer frames, yes.

ericm979

I've had some cheaply made carbon fiber motorcycle parts "yellow" from exposure to sunlight. I don't know if that is a structural issue or just cosmetic. Bicycle CF seems to use better epoxies or clear coats and be immune to it. Bicycles also don't sit out in the parking lot at work all day.

As far as heat goes, I have heard from custom CF bike makers that the epoxy they use is safe to 150-175 degrees. It'd have to be a black warehouse in the sahara to get that hot.

terrymorse 

Really?

Sure seems to be a lot of literature about the fatigue of carbon composites. There's even a book.

mihlbach

No, its real purpose is to prevent schrapnel when the carbon explodes.

BillyD

That's a damn shame, you got to worry about factors that will age/degrade your CF.

Nothing degrades your Ti!

Nothing!

Quijibo187

if you are worried about UV damage tp your CF frame (or paint or car trim or whatever else sits in the sun)
Treating it once in a while with this stuff helps to keep the colors nice and reduces damage. I use it on all sorts of stuff.

https://www.wholesalemarine.com/pc/30...rotectant.html

prxmid

So does carbon fatigue, or doesn't it!

Inquiring minds want to know

Drag

Well, we're carbon-based. And we get fatigued.

terrymorse 

Read the book, all 742 pages:

Fatigue in Composites

Short answer: carbon composites fail in fatigue.

ted ward

Reading the introduction should be sufficient for a BF member. The first few pages dispel much of the popular misinformation propagated on these forums.

Carbon Unit

Trek has a machine in their factory that they hook up to a frame that stresses the frame. They have left a frame hooked up to this machine and run it 24/7 for two years and the frame showed no signes of fatigue at all. This machine puts more stress on a frame than a rider would in a life time.

Also, a clear coat does protect against UV damage. My bike is just raw carbon without any treatment at all. Calfee calls them "Nude". If untreated, the frame can be damaged by the sun. So, I put 303 on it every few months. It could be done as seldom as twice a year. I live in Southern California which has lots of sun and I haven't had any problems.

TwoShort

There's actually not a lot of such literature. To paraphrase the introduction to that book (which you can read free on Amazon, like I did):

The fatigue properties of all sorts of metals have been extensively studied over the years, producing a great deal of information about them. The fatigue properties of carbon composites have not been studied nearly so extensively, hence this book, which will describe in great detail how and why the general rule of thumb regarding fatigue of carbon composites is not quite entirely correct. As a matter of reference, that rule of thumb is: Carbon composites don't fatigue.

As a practical matter in terms of actual bikes: until someone can show you a lot of cases of carbon bikes failing from age (not crashes) anything they tell you about how long they will last is BS. I don't know how long a carbon bike will last, because I've never heard of one failing from age so I can't say anything negative; nor have carbon frames been around in large numbers for long enough to say much positive beyond things look good so far.

Many people will assure you carbon frames disintegrate after some short amount of normal use. If any of those people have actual basis for that belief, I haven't heard it.

BillyD

I . . . I just had to.

Carbon Unit

Ti has it's own issues. Carbon is better when it comes to stiffness to weight ratio and strength to weight ratio. Ti does have a long fatigue life but so does carbon. The only advantage I see that Ti has over carbon is that it is more crash tollerant, but harder to repair if it is damaged in a crash.

Carbon Unit

Read this technical paper from Calfee on carbon fiber frame construction. It will tell you a lot.

https://www.calfeedesign.com/whitepaper1.htm

SoreFeet

Fatigue testing of frames on a machine is just BS industry talk. Carbon will ultimately fail at more cycles than aluminum or steel. It won't withstand side impacts like aluminum or steel. The modern carbon we see today is getting better and better but it still has structural limitations.

The only way to be sure if your frame is not broken is to use expensive MRI imaging. A simple look for cracks is not an accurate structural analysis.

I would not by a used carbon frame or one that does not have a reasonable industry warranty. Carbon frames are finite bikes. You can't have your race worthy bike and expect durability.

Recreational riders are fooling themselves with carbon durability. The bike shop says "its stronger than steel and doesn't rust." I have heard that spiel many times.

Reality is don't buy a race bike and expect a 20+ year service life. I had a trek bonded carbon frame that was a good rider but I felt scared the frame would eventually bust at the lugs.

Carbon does not fatigue like steel. It fails in an unpredictable manor. It's a fact. If you don't feel comfortable buying a frame then don't buy it. I can't recommend carbon to anybody unless they have a high disposable income.

WalksOn2Wheels

Well, as it turns out, this guy is an ex Trek and Specialized employee and anything and everything he has are sample frames ridden very little and to top it all off, he knows his stuff, so he's not going to sell me junk.

But do carry on. It only took me one short post to piss off half the board.

tkm

...this advertisement brought to you by the USW, United Steelworkers of America.



You can't be serious with this post, can you?

Carbon Unit

You are generalizing. Not all cars are the same and not all carbon fiber bikes are the same. A bike that fails just from riding it is a poorly made bike. Calfee has owners with more than 120,000 miles on their bikes and they ride just fine and this is with a frame in the 2 pound range.

Also, I have bought several used carbon frames and never had a problem with them. You just need to be very selective on what you buy.

Lastly, fatigue testing of frames is not BS industry talk. Many manufaturers fatigue test their products. Auto manufacturers uses robots to test door hinges and other items that wear out. Most large manufactuers have a R&D department that looks at ways of improving their product so they are more competitive in the market.

tkm

Please let me know how many lifetimes it takes you to fatigue a carbon bike to the point where it is no longer ridable.

Then let me know how many years the same thing happens with an aluminum bike.

If anything, people should be just as wary about buying a used aluminum frame as a used carbon frame.

StanSeven

The boats survive.