Carbon frame life cycle

Many of the comments here are based on made-up facts and urban cycling legends. As someone has already mentioned, many modern aircraft are made of CF because it is the lightest material that offers superlative levels of structural integrity.
Anyone suggesting that CF is more likely to fail is quite simply mistaken.

Gordy748 posted:

"Carbon has a fatigue life and, over time, flexes more and more every pedal stroke. Every time this happens, it absorbs (fractionally) more and more watts produced by the rider. For a pro, the point at which the frame is unacceptably flexible will happen a lot sooner than a sportive rider."

sorry, this goes against current technical understanding and material behaviour of composites (which is another reason they are now used in passenger aircraft)

one of the big bonuses of carbon fibre composites is that in normal use (in the design envelope) they do not fatigue (unlike aluminium alloy) and withstanding catastrophic impacts (crashes) or environmental degradation (exposure to UV, road salt, etc. which can be guarded against with good finishing) should easily outlast metallic alloy framesets

of course, this assumes good quality control during manufacturing and no in-built 'design flaws' to the composite design or galvanic corrosion from in-moulded metallic alloy hard points (this is why manufacturers are moving to all carbon frames with carbon dropouts, headset cups and bottom bracket tubes)

There's been some discussion, suggesting that if aircraft are made of carbon then carbon bike frames must be just as safe, so I thought I'd just quote what carbon-bike-check.com say on the subject, over in Germany.

"A plane consists of large, massive components which reinforce and support each other. Most are large machine-made components which help reduce inconsistencies. Each part is checked and tested after assembly as a whole. And that is for example the difference between an Airbus and a bicycle. An Airbus is tested and tested and tested. The aviation standards define exactly what, how and how often a component is to be tested. And for bikes, is there nothing? Actually, there are standards but these apply to Type Testing meaning the design is tested using samples before production but they do not apply to the production itself. They are also not mandatory. "

They also go on to say that "a defect-free frame, fork, stem, etc. does not exist", and that "many failures could have been prevented if testing had been carried out beforehand". Ok, CBC's business is the testing and analysis of composite materials, but it certainly makes sobering reading.

I'm fairly sure that no one said it would fail....just that it loses its stiffness.

As for aircraft, yes, it's used as an alternative to....aluminium.....which the thread seems to agree has a low stress life.

I'm not against carbon, I have carbon, I use carbon, but I still believe it has a limited life in use in the real world...just as that expensive re-enamel does on steel.

I crashed my carbon TT bike at 25mph. It just sucked it up and Im still racing it 3 years later.

I have carbon forks that are donkeys years old too

Some bizarre comments on here - clearly a little knowledge is a dangerous thing.

How long will a carbon frame last?

Indefinitely, as long as you don't crash it or leave it exposed to the elements on a permanent basis (this last part strangely, is true of most bike frame materials).

If you feel the urge to crash your bike regularly buy something else but but recognise than nothing can be fixed 'good as new'. What ever you buy don't leave it out in the sun, rain etc - but then if you're looking at high end carbon I'm guessing you weren't intending to?

I have carbon, steel and aluminium. The steel is 20+ years old and weirdly has rusted. The aluminium has unusually failed to snap yet (15 years old) and the carbon is still going strong despite only having paint to act as a sunscreen. I don't have a titanium bike yet, or a beard but who knows, both of those things may be in my future.

talking about forks, but you get the idea...

http://velonews.competitor.com/2011/07/bikes-and-tech/technical-faq/tech...

"I have tested a lot of steel (mostly True Temper brand tubes) and of course carbon (lots of brands) in fatigue tests and also load-to-fail tests. In high fatigue loading, the carbon forks would eventually lose some stiffness (as much as 5 percent) after many thousands of cycles to represent many years of actual riding conditions. So I would not say the forks would last forever at high loading. You don’t hit high loads on most of your rides though … You should get a lifetime of JRA riding (just riding along).

Steel forks did not lose any stiffness in the fatigue tests. They are typically kind of over built so they never got stressed past the endurance limit (about 50 percent of ultimate tensile strength). In load-to-fail tests, the steel forks bend until they crack, or we would stop when the fork had bent more than 10-20 percent (un-useable).”

So there you go. Sleep easier.
— Lennard"

Sooooooo booooooring can't believe I read all of this.

I say this

Well I say this

But I say this

You're all wrong I say this

Yawn