TandemJeremy – Member

Carbon fibre scares me on mtb components not because it is weak but because of its brittle nature. Overstress a metal component it will deform. Over stress a CF component it will break.

I’ve had an alloy seatpost snap under me. Not pleasant.

A standard hardtail carbon frame, ie not cutting edge unidirectional high modulus carbon or similar will roll out of the doors in Taiwan for between £100-150. Something more decent like a nice Spesh S-works frame might be heading towards the £250 mark. (Might…)

Most bullshit in a thread EVER!

I get the feeling lots of people have bad memories of CF in the ’90s. Modern CF is pretty strong, there was a good discussion about this in the DIN testing thread two or so weeks ago.

The problem with CF failing is that it does so without any warning (no visible cracks etc) and does so in an instant

If it was made of one single piece of CF, rather than hundreds of pieces all laid up. Early carbon frames (Giant MCM etc) had an insane amount of paint on them to protect the CF from getting scratched or gouched by rocks. Modern frames (Ibis mentioned aboved being an exception) don’t have this. A scratch is no longer an issue, as the layup of the carbon is multi-directional and multi-layered, preventing a propagating crack or tear that would cause a catastrophic failure such as you get in aluminium.

The other aspect is what is the advantage of a CF frame? How much of the weight of a nice light bike is the frame? 4 lbs out of 25? so save 1/2 a pound on the frame – does it really matter?

Matters a lot. I’m currently riding a 3.5lb (including shock!!) full-suss frame. That’s lighter than most alloy hardtail frames. So yeah, it does matter if you’re design goal is to make comforts such as FS without the weight penalty usually associated with them.

Maybe at the end of the day it comes down to the XTR chainrings argument: If you’re fat, slow, clumsy, can’t afford to replace it or just don’t want it, vote with your visa card and buy something else.

A standard hardtail carbon frame, ie not cutting edge unidirectional high modulus carbon or similar will roll out of the doors in Taiwan for between £100-150. Something more decent like a nice Spesh S-works frame might be heading towards the £250 mark. (Might…)

When sprouting, can people please cite sources.

I ride my Giant Anthem Carbon as it is a noticeably better ride than the alloy equivalent. Its not even lighter – the new alloy Anthems are lighter than the carbon 08 – its not about the weight. Its about the ride. Its super stiff and ‘feels’ faster to me.

Plus its had more than its fair share of offs and rock strikes. It seems absolutely fine and i trust it implicitly.

I can speak from personal experience about the problems/advantages of carbon frames. As I have posted before, I have had three carbon frames, all of them failed, all at stress points where elements were bonded together. None of them failed catastrophically- I noticed a crack in the paint on the first two and the third stared creaking (I was paranoid by then and discoverd another crack just below the rear suspension pivot point on the seat tube hidden by the rocker arm). The frames themeselves were fantatsic to ride when in one piece- stiff in the right places, flexible in other directions to give a smooth ride. I believe I was unlucky as I know of two other people with Giant carbon full suspension frames that have lasted four years with a large number of “incidents” between them and one of these has to carry quite a lot of weight..
However I now won’t buy another carbon frame – and none of my mates will let me any where near theirs!

If we’re onto the old “carbon breaks” chestnut – so does everything, depends how it’s made.

I had a carbon DH bike (remec). It died at 6 years old, having spent many weeks in the alps, SDAs, NPS etc etc.

What broke?

The alu headtube insert, in a high speed crash at fort bill that put me in hospital in a neck brace. The carbon was fine.

All materials fail. Its just that people love to bang on about carbon for some reason.

What are the environmental costs of carbon fibre? Its plastic isn’t it, essentially? Is it in any way sustainable?

My guess is that steel is the most sustainable, and probably requires the least energy to manufacture (lower heat, etc).

I would love to hear what an engineer/materials expert thinks is the least environmentally destructive material to build a bike from.

I only read as far as “The problem with CF failing is that it does so without any warning (no visible cracks etc) and does so in an instant” and lost the will to carry on.
In your opinion (god forbid experience), does it shatter like glass? Do you own have or have you ever owned a carbon fibre bicycle component, less actually seen something carbon fibre break?
I have carbon fibre on my mountain bikes and two carbon fibre frame/forks/steerer road bikes. If I could afford one or somebody reading this has lost confidence in their 18″ carbon Scott Spark, I’d have it and I ride almost exclusively in the Peak District
I love these threads about carbon fibre components and bikes.

Surprisingly, Ive seen more alloy bikes fail then carbon. My mates got a saracen kili flyer (spelling?). Thats a full carbon frame. We ride lots of technical stuff, and he falls off hard all the time. Never managed to damage his frame though.

I’ve had a set of Trek OCLV fork blades fail on me, just below the brake caliper. It wasn’t pretty.

I have carbon failure paranoia.
I had a carbon NRS and was overly careful riding it and each chip felt like I was sitting on mini time bombs.
I’ve seen a few carbon failures; two Yeti 575’s one Easton seatpost and Pace 29er forks all doing xc stuff with the exception of one of the Yetis failing at Afan.

I love the fact that people speak of carbon fiber when it’s most likely to be composite fiber made of kevlar/carbon/glass fiber.

And just to cut short of all the idiotic comment on F1/motoGP. They are meant to run in a complete different manner than off-road bikes. Plus most of the time they are used to gain stiffness or to solve a specific engineering problem, not to save weight as it seems to be the norm in the cycling world.

If carbon was so much good, don’t you think dh bike would be made of carbon? Or enduro bikes?

When I was young (and all this was fields), frames were steel – cheap mostly as well. My first real MTB was a Kona Explosif. I still have that frame as my turbo trainer bike and it could be built as a nice hardtail if I wanted.

At that time, aluminium was starting to make greater advances in MTB frames and the forum equivalents of the time were full of tales of life expectancy, cracks, failures and the like.

What was utter tosh, mostly spouted from opinionated people working on rumours and no knowledge has evolved from ally to carbon fibre.

I have three bikes I ride most, all their frames are carbon fibre. I bet my life that the carbon fibre won’t cause me to die. Poor riding might kill me but my choice of frame materials is low down on my risk table.

If you really want to worry about what might happen if you have some completely bizarre CF failure that then causes a crash etc. etc. then you need to try another sport. It makes more sense to wear a lot more body armour than worry about the CF failure. btw, CF is OK for body armour to 😉

RudeBoy – Member

Your bones are made from Carbon Fibre. They are very light, and have incredible strength, considering their weight.

Are you sure? maybe I hav e read your post wrongly?

We’re carbon based, but the chemical/physical structure involves the carbon but not carbon fibre which is structurally/massively different.

There is carbon in oil, alcohol and many gases but carbon and carbon fibre should should be confused as the same. Hugely different and involves different elements and arrangements.

Anyway I wouldn’t trust myself with carbon fibre for xc as I crash alot.

On a road bike it is great depending on the type and grade. It is strong, flex and comfort and light. My other alumy roadbike is harsh but has it’s pros too-fallen enough alot…

RudeBoy – Member

Your bones are made from Carbon Fibre. They are very light, and have incredible strength, considering their weight.
No they are made of collagen and it’s as far as carbon as iron or steel can be (the wiki link about collagen is correct and well quoted).

Hugely different and involves different elements and arrangements.

er, carbon fibre IS made of pure carbon. The whole of organic (and biological) chemistry is based on carbon compounds, but elemental carbon (graphite, charcoal, diamond) is rather unreactive…

Was put off cf when this happened (to be fair the chain stay was pretty dinged as well)

elemental carbon (graphite, charcoal, diamond) is rather unreactive

If that were true it’d make for rather unsatisfactory barbecues.

If that were true it’d make for rather unsatisfactory barbecues.

at normal temperatures 🙂

Good greif, carbon fiber makes people angry? Forums!?!? 😀
It was just a question and as I said willing to be proved wrong…I just imagine that i would as someone else said above be teatering about terrified that I would ruin the bike rather than plowing though stuff but if carbon is ok with knocks e.c.t then well…

It’s not so much about if a materials going to break, of course frames of all materials can snap but my specific worry is the impact of stones e.c.t which were I ride are an issue. It had to remember how many times I have had large rocks ping off the downtube without issue, I just wondered if carbon fibe would really be the best thing…

As pointed out above CF is use in F1 alot as it can be built to be super strong but it does undoubtly shatter on impact…this is what worries me, not that i am traveling at F1 speeds, sadly!

Maybe it’s just a personal thing and depends where you ride…

Was put off cf when this happened (to be fair the chain stay was pretty dinged as well)

Correct me if I’m wrong, but that looks suspiciously still in one piece. So your issue is that you have a big impact of some sort (might be more useful with a little context), and a cf frame gets damaged? Have you never seen an alu/steel/ti frame broken in a crash? This whole thing about cf not being able to take rock impacts is a complete myth – the sort of impact needed to break a cf frame would doubtless also break a frame made of any other material.

I’m sure some of the slight scratches on my trex fuel, if they were on the carbon models would have resulted in the carbon weave being damaged

Maybe, but that’s not actually the sort of issue people seem to think – the outer weave layer is largely cosmetic.

lol at this thread.

If you want to believe that cf is brittle/weak/fragile/whatever then just don’t buy one but it’s probably your loss in limiting your options.

I’ve broken several frames: steel and alu. All have cracked due to fatigue either from design or rock damage (stress riser). Not one has failed in a plastic deformation way that tj mentions. Same for bars, cranks and seatposts.

Thin walled metal tubes are very prone to damage from rocks (stress risers leading to fatigue or just plain beer can crumpling) – arguably more than cf since the wall thicknesses are often very low.

I have also had quite a lot of experience with cf in another sport – rowing – which you might think is pretty tame but boats and oars actually take a hammering. I think I’ve seen two oars fail in around 20 years – both to the equivalent of hitting a bike frame tube with a sharp edged object with massive load ( momentum of eight people plus boat ). I’ve seen many similar big impacts leave the oars undamaged despite being bent well beyond what they were designed for.

Cf manufacturers test their cf products in all sorts of different ways, one of which is dropping a heavy bar on a tube. The cf stands up to the abuse far better than alu though admittedly this is often probably because cf products tend to be designed with larger safety factors that can be got away with due to the inherent low density.

I don’t have a cf bike but only because i’ve not found one cheap enough when i’ve been after a new frame but I’d have no issue buying one otherwise.

carbon fibre doesn’t shatter on impact btw. F1 crashes massively over load the parts that break eg suspension arms, wings, etc. The main survival cell stays intact as it’s meant to.

Alu would just crumple in the same situation. Not actually any better…

The real problem isn’t the material its educating people who are scared by the old wives tales ,theres always someone who knows someone who had a bad experience

at the curret rate CEN tasting is going steel bikes are coming in at 5 lbs plus thats a hell of a lot of carbon fibre to go play with …

http://www.youtube.com/watch?v=5N9uZupdGhQ

and found this…for the roadies 😉

http://www.youtube.com/watch?v=FwGLoRFvf1k

http://www.youtube.com/watch?v=RtZhG2kWVLY

alternative uses for a road bike…..lance pegging it across a field

So, a low spoke count wheel with ultralight rim breaks when loaded 90 degrees to what was designed. What would an alu rim of the same weight have done?

If CF is so weak and “bones are made of it” – how come
the dog isn’t broken?
😆

carbon is shite , it cant take the weight of a steamroller or an excavator LOL 🙂

my dear lord theres some bullshit being spouted in this thread!

1) my dissertation was on fixing strain gauges to hih end easton hocey sticks. Thise things took a lot of abuse!

2) i had soe RF deus flat bars which got a chip so i decided to listen to the naysayers on here and ‘bin them’. Just to see how weak they were me and my housemates too turns swinging them like baseball bats into walls/door frames/floors until they broke. They never snapped, creaked a lot, but never actualy snaped.

I am surprised that DH bikes don’t use carbon fibre frames given the recent desire to shed weight
I can only think of two reasons why they wouldn’t – expense and strength

The real problem isn’t the material its educating people who are scared by the old wives tales ,theres always someone who knows someone who had a bad experience

I would have said that the real problem is separating the marketing bull from the facts.

My alu frames have always worked well, as have my older steel frames. At the moment why would I pay the extra dosh for a c/f frame that weighs roughly the same, handles the same (assuming the same geometry), ie does the same job as the cheaper metal frame but costs x100s more.

Yes, you can get ultra-light c/f frames, but then you can get ultra-light alu frames as well. Put my 14 stone on them on the rocky warzone of Kilvey Hill and they all feel like they are made of bamboo.

Incidentally I used to work for a company that replaced bikes for insurance companies, I did the warranty work. We rarely had any frame warranty claims of any kind, and never had a carbon warranty iirc, BUT I saw quite a few crash damaged c/f frames. Having said that, we would write off any alu frame that had been involved in an RTA because we couldn’t tell how damaged they were at all. What was quite scary was how easy it was to dismantle a c/f frame to put it into the bin.

What’s a

hih end easton hocey stick

?

One major advantage of Carbon over Alu is that if (IF) it does break, it’s cheap and easy to repair. Your alu frame breaks, it’s over really. CF can be repaired for as little as £40 for a crack, and you won’t need a respray.

It’s also a lot tougher than a lot of people would have you believe.

Just wondering how many people actually have a carbon bike? All the rubbish about carbon failing and not taking loads, plus the tosh about structual strength. Carbon is one of the strongest materials by weight , and retains its strength even whilst flexed. Have you picked up a high end fishing rod recently? Way lighter tha your old glass fibre poles , and will repeatedly flex through 90′. Most break by being shut in car boot or door.
Windsurfing masts are also high carbon content, Yes you can buy a 20% carbon mast , but 90% one is stiffer /lighter/ stronger . Anyone who has seen what a mast goes through every time you rig , then go out in a F6 and stuff them through waves and shorebreak wouldn’t bleat about catastrophic , brittle structures that instantly fail.
Wind farms blades are carbon fiber, and designed to flex and last years.

Admitadly all of the above will not have stones catapulted into them but will all take a pounding. Carbon is possibly not the best for full DH bikes, but for XC and general trail riding they are fine.

It never ever crosses my mind as I ride along that my bike is about to instantly fail and kill me. I will break before my bike does. And my bike was made in 1999. Not in the same way as modern carbon bikes, but as a thermoplastic lay up method squashed on a mandrel under 5000 psi , leaving a destinctive ‘spine’ . They do fail, but only where aluminium is bonded to carbon, where over time the epoxy glue fails. In most cases its a 20 min job with araldite to refix the seat post insert, or head tube insert back in.

Haven’t read all the posts but didn’t think being uninformed mattered much.

My Carbon Fibre Scott Strike is 8 years old, has had me riding it, has crashed many times at varying speeds from stationary to 30mph+, has hit things such as sheep, badgers, trees and other riders.

It is still in one piece and seems as strong as ever.

And just to cut short of all the idiotic comment on F1/motoGP. They are meant to run in a complete different manner than off-road bikes. Plus most of the time they are used to gain stiffness or to solve a specific engineering problem, not to save weight as it seems to be the norm in the cycling world.

If carbon was so much good, don’t you think dh bike would be made of carbon? Or enduro bikes?

Juan; did you see the pic I posted, of Kubica’s crash? YouTube it. Kubica was sitting in a CF monocoque, which protected him from impact, and saved his life. The fuel cell is in a CF pod. No fuel escaped, and caused an explosion. CF is used in F1, because it has perfect properties for certain applications, and can be made incredibly strong. To produce an equally strong monocoque in Alu, would weigh loads more.

CF is used for good reason. Top bike manufacturers use CF, because it is a bloody good material to make bikes from. A CF frame, the same weight as an Alu one, could be made that would be a lot stronger. I would imagine those manufacturers would have done extensive tests and analysis, to ensure their products do not fail even under extreme conditions. The examples of damage to CF frames cite accidents, serious impacts, which would wreck steel, Alu or even Ti.

There are several ‘enduro’ bikes made from CF. As for DH, considering top-end DH frames cost £2k+, a CF version would surely be astronomical, and therefore woon’t sell. I’m sure there a few secret prototypes around, though.

As for my comment re bones; I was not being that serious!

how come the dog isn’t broken?

Poor dog.. 🙁