Check for the carbon fiber

mcdonji1

Send your bike by DHL. I have just recieved a carbon frame for my next project and the box had been x-rayed.Perhaps they could include the slide with the parcel. Wonder what an x-ray of a box with carbon frame in it looks like? A wee pic of the metal inserts and the gear hanger?

Jim

cougie

<scratches Isaac off my list of bikes to buy>

Carbon seems fine to me - I've had mine for three years now, and its survived 6 flights and thousands of miles.

Bronzie

I had a stack at the Dragon Ride when the guy in front of me fell off and I T-boned him and went over the bars breaking my collar bone in the process.

Three weeks on, the collar bone is healing (after a fashion - I shall cycle in circles until I can hold my arm straight ). Finally got around to checking my bike - Cervelo Soloist Team - aluminium frame with all carbon forks. There's hardly a mark on it - think the saddle hit the ground first and took the brunt of the impact.

But there appears to be a hairline fracture at the base of the carbon steerer tube where it meets the fork crown. Got my mate who works for Trek to have a look and he reckons it'll be OK....................but the forks are a highly loaded part of the bike, and if they fail, the consequences don't bear thinking about.

So I've decided to replace them................can't afford the Cervelo Wolf forks (£300 RRP) so I went with Reynolds Ouzo Pros (a bit heavier but look well made and trusted brand). I got them for £100 from Phil Corleys in Milton Keynes - reduced from £300 (still £200 on Wiggle tho') because the after sale carbon forks market has apparently died a death now most frames come with carbon forks as standard.

Have I wasted my money...............maybe, but having my forks snap on a fast descent doesn't bear thinking about.

Yours in paranoia
Bronzie
xxxx

giant_man

FFSake wrote:

giant mancp wrote:

I think you're worrying waaaay too much here jaws. When you buy a new carbon frame it will be perfect, and depending on how you use it, it will always be perfect.

Oh dear.

What do you mean 'oh dear' FFS? There is nothing wrong with carbon fibre. Prove otherwise foolish man!

pliptrot

Bronzie,

IMHO many people on this forum are far too sanguine about carbon fibre. I've asked if anyone has data on failure rates and so-on in the past -evidently they do not- but anecdotal evidence supports the concern that carbon fibre can - and does- fail catastrophically and without warning. It's also difficult to detect some damage which may cause such failures.

I think you were dead right to change the fork. If for no other reason, can you put a value on peace of mind?

A more contentious point is that most carbon fibre bits for bikes come out of China (other than your new fork, by the way), which - if you believe the recent news on poisonous food, substandard materials, fake drugs, dangerous car tyres and the like from the PRC- makes them very suspect, if only because I want to buy something I can trust. Trek make their carbon fibre frames and forks in a highly secure plant in the US, which suggests 3 things;

1. they have a superior product (or material) which is worth protecting,
2. they have a decent (developed country) workforce who have decent conditions in which to work,
3. this is all part of the marketing hype.

I doubt anyone is so cynical as to go with (3).

Best regards,

Pjl

Philip Davis

Plop, carbon fibre frames fail catastrophically because they have a high modulus of elasticity (i.e. brittleness). This is one of the reasons engineers are cautious about using it in many structural uses - it either stays intact, or fails immediately. The 'middle ground' is commonly known as metal fatigue, which, as the name implies, is a characteristic of metal. As i posted above (obviously not clearly enough for some people), the flip side of this characteristic is that carbon fibre is highly unlikely to have hidden cracks or flaws caused by impacts (unlike alu, steel or ti). So arguing about x-rays or otherwise misses the point about the nature of carbon fibre. If you ride a carbon fibre component you get something that is gram for gram, very strong, very resistent to fatigue, excellent 'memory' characteristics, but the flipside is that if it is pushed past its limit, it will break in a more rapid and potentially catastrophic way than metal, and with less warning (i.e. no creaks or groans or visible distortions from the structural part). Thats why most carbon fibre components are relatively overengineered, so are in general stronger than equivalents.

The exception to this is failure at bonding points (probably the most common type of failure). Its well known in the industry that bonded parts are more difficult to manufacture to a consistent standard than rivetted or welded parts (thats one of the reason why the bonded plywood wings of the Mosquito were never used much outside of wartime necessity). It is always wise for anyone with a bike with bonded parts to occasionally give a good visual inspection just to see if there is anything that looks dubious.

And contrary to what you state, very few carbon fibre components come from China. The main manufacturing centres for sports goods are Taiwan, the US and Mexico.