Fear of carbon

[beardy]

A materials engineer can make a good prediction of what a material will be able to offer but they will never be as able to state facts as a horde of real life users. Practice trumps theory every time.
If they say it is safe and they keep breaking, who is right?

There is more to be gained by playing safe when giving "advice" as if you say replace every year, they pay the bill. If you say ten years and it lasts nine they start pointing a finger at you.

Now that CF bikes are out there in large numbers what happens to them is what material scientists will be looking at, just as the rest of us are. I have seen enough old and high mileage carbon fibre forks out there that I am no longer worried and will not replace mine at five years as I originally thought I might when I bought the bike.

[Brucey]

some of us are materials scientists and engineers. Building CF bikes is complicated, and is mostly carried out far away, under process QA conditions that can only be guessed at.

People generally want simple advice, even in complex situations.

My simple advice is this; caveat emptor.

cheers

[pete75]

If only there was a materials scientist amongst the forum regulars...

These websites may provide info on failures in CF frames and lots of other cycle components made out of all sorts of stuff.

http://materials.open.ac.uk/mem/mem_ccf.htm

http://www.pardo.net/bike/pic/fail-001/000.html

[jb]

One only has to wander into the great 'world trade center conspiracy theory' to see people totally misunderstand materials. all anecdotes & preconceptions.

[[XAP]Bob]

Hi,
Worryingly however, the boat’s designer Adrian Thompson said getting the balance between strength and lightness was tricky: “Simply, a boat that is impossible to break will never win” he said.[/i]"

Of course it could - particularly if the weather was such that the competition all failed...

[Flinders]

I'd inagine the likes of TdF riders don't keep their bikes for 10 or 20 years like some of us do, riding right through the British Winter.
I have Alu + CF forks, the only frame I could get to fit me properly. Previously I had steel.

On what I've read I wouldn't want CF from a cheapo manufacturer, as the production of it needs to be done with great care.
I like the stiffness of my current frame compared to my previous steel ones. But that's probably as much the change in geometry as anything (the current frame is better proportioned for my size).
I gather (and the materials people here will no doubt correct me if I'm wrong) that at least some steels can 'self heal' some fine cracks; I don't suppose CF does that. I do keep a careful eye on my frame, but haven't found any cracks yet, though the crossbar had an iron bar fall across it, which just chipped some paint off. Had that part of the bike been CF, I'd have been a bit more concerned about it.

[hamster]

Hi,
Worryingly however, the boat’s designer Adrian Thompson said getting the balance between strength and lightness was tricky: “Simply, a boat that is impossible to break will never win” he said.[/i]"

Of course it could - particularly if the weather was such that the competition all failed...

Bombproof boats are called cruising yachts. When you see how fast a racing boat goes by comparison you see Thompson's point. It's an unhappy owner who will be told his boat will only win in the 1% eventuality of a hurricane wiping out the entire fleet. However, to finish first, first you have to finish. So it has to be just strong enough. The winning Whitbread boats in the 1994-5 race all suffered severe delamination...but still won. Nowadays it's not a problem as the material specifications and scantlings are better understood.

If you've never seen a foiling Moth then you ought to. Desperately fragile, but 30kts from an 11 footer is impressive. Racing offshore in the past there was one desperately slow 33 footer, which one day suddenly picked up her skirts and shot past the majority of the fleet downwind. Shortly after she rolled over, the burst of speed was the aftermath of the keel falling off.

[maxcherry]

Orange are recalling the forks on the bike I wanted to buy

It was a steel cyclocross bike as well. I think I will be sticking to my single speed Genesis.


http://www.orangebikes.co.uk/news/view/rx9_fork_recall

[Bicycler]

It's advertised as Aluminium

[maxcherry]

It's advertised as Aluminium

I don't read adverts! I just go for 'Pretty'

So is alu better?

[reohn2]

Orange are recalling the forks on the bike I wanted to buy

It was a steel cyclocross bike as well. I think I will be sticking to my single speed Genesis.


http://www.orangebikes.co.uk/news/view/rx9_fork_recall

Well they're aware of the problem,have recalled the faulty ones and no doubt the ones being sold now will have been checked.
Some time last year Salsa recalled forks on their Vaya models,the problem forks were replaced and now all is well.Or as well as can be.
I own two Vayas and I'd buy again without a second thought.

[Brucey]

There's no issue with carbon it's as strong and durable as any other frame or fork material.

Except when it isn't.

And 'it' isn't even the same thing in every case anyway.

Just imagine for a moment that your sphere of professional expertise was (say) the political situation in Syria or the epidemiology of the Ebola virus. Now imagine just how appalled you would be if you were trying to have a rational discussion with (say) a bunch of ill-informed, highly opinionated tabloid newspaper readers on either topic, who found it easier to cling to gross generalisations and half-truths than to actually grapple with what is really going on. It is complicated!

If you want an example of how the unforgiving nature of CF failure can bite you in the backside despite your best precautions, go onto you tube and look for Eric Barone.

There are people here who have lost friends to broken CF parts; if you think it is all 'perfectly strong' then you are living in a Dream World.

cheers

[pete75]

The design engineers at Ferrari are experts in their field. They are amongst the best in the world at what they do. They've been using CF in their racing cars for many years and now choose carbon fibre to make the monocoque chassis for their most expensive road cars. Obviously they think it perfectly strong.

If any here are making gross generalisations it's those who imply that CF is at a very high risk of failure. Like any other material it will fail but what percentage of CF frames fail - or more pertinently what percentage of CF frames that haven't been crashed or otherwise abused fail.

As for Barone that's a bit of a red herring all it shows is that particular CF frame wasn't up to descending a mountain at over 100 mph. The same will apply to most frames made of various other materials as well.

[jb]

There is no equivalent of a front fork in a monocoque chassis. There's a lot more room for redundancy and still have big weight savings because you're dealing with a larger mass.

[Brucey]

the engineers at Ferrari have knowledge of and control over their manufacturing processes. Car chassis design is interesting because it is mostly driven by stiffness rather than strength. When the strength and energy absorbing properties are most important, you are having a crash, and it only needs to be strong once.... After that it goes in the bin, which is how it should be.

People persistently refer to 'it' as if 'it' is always the same stuff. It ISN'T; no more than Cr Mo is the same as 753 is the same as gas pipe, or good welds are the same as bad ones. You can buy some right crap.

Barone's crash is quite telling because he and his team obviously spent some time planning his record attempt, and thought that they knew what they were doing. It is a perfect example of how things can go wrong despite careful planning. Had Barone's team taken style tips from other bikes meant for that kind of use he should have wound up looking at MX bikes. They are almost invariably still made of welded metal tubes, they still use wire spoked wheels. I can only assume that MXers are not taken in by the hype, for as we all know CF MX bikes would be 'so much better' because CF is always 'perfectly strong'....

cheers