Are carbon fibre and aluminium strong enought to make frames and forks from ?

[HillSpecial]

Are carbon fibre and aluminium strong enought to make frames and forks from ?

Since my accident * I often hear of CF and aluminium frames & forks snapping. I wondered if any organisation, eg the CTC, BSI, or British Cycling etc is doing any research into the frequency of such failures?

*I was out on the bike and had been doing well over 40 mph {down hill} andthen when I was, 'luckliy', doing less then 20 mph the aluminium fork steerer on my carbon forks snapped off just above the top headset bearing - see below - the handle bars came away in my hands and I fell off my bike, landing on my right shoulder and head, breaking my collar bone {clavicle} and my helmet was broken in several places - but my head was OK. I also sustained cuts and bruises. I was taken to A&E by ambulance, 'gas and air' and morphine en route. My accident was similar to George Hincapie's . . . .

see http://www.youtube.c...h?v=UZg1vrvGbdE



I've since returned to steel framed cycling !



Cheers,

on yer steel bike,

HillSpecial.

 

[mickle]

My friend sheared one fork leg off of his (steel) Gazelle roadster last week at the crown.

Where does this leave us?

 

[Rohloff_Brompton_Rider]

funnily enough i was down at my lbs today where i got my giant tcx1 from. i was enquiring about the possibility of getting a set of alloy forks. i just don't seem to be able to settle down when riding with the carbon forks it came with, my reasons to be unsettled is that my scott genius ltd full carbon fibre mtb (£5000's worth) snapped in half due to a manufacturing fault (fracturing my eye socket and wrist and i was knocked unconscious for a short while). the frame was replaced by scott and the bike rebuilt by lbs, but i ebayed it.

the bloke at the lbs (craig at rideon in rossendale) is very knowledgeable and is involved in quite a few research and developments (bike related). rideon are giant dealers and craig goes to all the meetings a dealer has the opportunity to goto. he's been to a few where giant rep's talk about quality and prices and some others where they demonstrate the manufacturing process and quality control.

apparently not all cf is the same, i.e giant get the actual fibre's from the same place as boeing and f1 teams. in other words they get the best available, then they weave it in house and produce the components in house and keep a tight grip on quality. apparently giant have the ethos of it has to be 'fit for purpose' (which causes passionate arguments at dealer meetings, dealers want cheaper bikes to compete) and not built to compete with 'boutique' brands on lightness (eg, pinarello, colnago etc etc) the boutique companies buy in the already woven cf matting and 'swatch build' their frames with the ultimate goal being lightness and stiffness (fair enough, horses for courses).

giant actually build and have their bikes tested to some crash test standards (craig said EN summat or other) and are heavily involved with improving the standards of all bicycle frames and forks. craig says he really believes the company (giant) operate a show all policy and gets monthly emails regarding failures and recalls. he reckons in all the time he's been a dealer he's not heard (not even on the grapevine) about any problems with giant cf frames or forks.

now i'm not naive enough to believe everything i'm told by a dealer (obviously he may have an agenda) but craig seems to be a straight up guy and wouldn't sell cf mtb bikes until he started being a giant dealership.

what do you guys think? has he been straight with me (or giant straight with him).

i'm particularly happy with how he told me giant make their cf forks; a swaged end on an alloy steerer tube and then inserted into the machine that bonds the tube to cf & resin, i.e., not cold glued into a crown like a lot of companies used/do.

ribble bikes was one of the companies that was mentioned in the cheap chinese carbon category.

 

[Fiona N]

Next we know the OP will be warning against flying - all those dangerous weak Al and carbon fibre planes ought to be replaced with steel ones

Who are these mind-bogglingly ignorant people who go on about the 'strength' of a material as if it only comes in one - dangerous - form? I suggest they all move to wood bikes and avoid all technological materials as occasionally some component makes it past the QA test and fails in use. Humans being fallible, it's always going to happen

 

[Rohloff_Brompton_Rider]

Next we know the OP will be warning against flying - all those dangerous weak Al and carbon fibre planes ought to be replaced with steel ones

Who are these mind-bogglingly ignorant people who go on about the 'strength' of a material as if it only comes in one - dangerous - form? I suggest they all move to wood bikes and avoid all technological materials as occasionally some component makes it past the QA test and fails in use. Humans being fallible, it's always going to happen

ooohh a bit harsh fiona. i've had alloy,steel and cf bikes fail on me. the thing that worries me is that cf can be damaged or built wrong and normal mortals can't tell. so i know where the op is coming from.

 

[Fiona N]

ooohh a bit harsh fiona. i've had alloy,steel and cf bikes fail on me. the thing that worries me is that cf can be damaged or built wrong and normal mortals can't tell. so i know where the op is coming from.

yes - sorry (can't find a contrite face ) - I've got tooth ache

I've had all sorts fail on me including a steel frame snapped clean in two (not to mention the two steel hand-built frames hanging in the garage awaiting some re-brazes). But that's the thing, you (apologies, one) can't tell whether a weld/braze been overheated and is brittle to the point of failure any more than that the resin's not interacted with the carbon fibre properly etc. I guess one saving grace of steel is visible, volume increasing, paintwork disrupting rust.

Quality items usually require a good 'quality assurance' system of some sort - often that's where the cost is, as lower cost items are essentially the same as a higher cost one but the latter has to make a higher quality threshold which means that a higher percentage are failed. But all QA systems fail - a failure-free system is an impossibility. Anyone who works with safety systems knows that if there's a human in the chain, you're doomed, basically, and it's the same with QA. Thus manufacturers know they have to live with a certain rate of failures, some of which will be costly - that's why they have insurance.

But I don't think there's any difference in the essential 'quality' of steel v. Al v. carbon. Each has their own strengths and weaknesses and their own failure modes - personally, I like the fact that corrosion down the insides of tubes is not an issue for carbon frames as I've lost a couple of steel frames with incomplete anti-corrosion on the inside and me not paying enough attention to getting the water out of the BB/chain stays. I've had corrosion of an Al mtb frame where microbial activity under, well let's call it 'dirt', caused local corrosion and failure. So far I've not delaminated a carbon frame nor had any quality issues although I did retire some carbon forks with a steel steerer after a side impact. The damage might have been more obvious on steel forks but you have to make a judgement on whether you're willing to take a risk for want of £100 for new forks.

 

[Davidc]

I've had steel fail on me (caused by rust in a seat stay after 20 years)

I've had aluminium fail on a family member's bike (I'd have failed if i'd been treated like he treated his bike, but it was supposed to be fit for that purpose).

I've seen the delayed aftermath of a ding on a carbon frame - not mine - it snapped.

None of these led to any injury beyond scratches and bruises, with less luck they could. There's always a risk of failure, even if the appropriate material for the intended use is chosen. Ultimately if the risk is unacceptable to you you'll have to give up!

 

[ColinJ]

I encountered the owner of this bike after he had dismounted, having noticed that his mudguards had suddenly started rubbing. Fortunately the failure happened on the flat, not on one of the steep descents earlier in his ride!

Admittedly, he should have noticed those rust patches before the forks broke but I can see how a steel frame or forks could rot through from the inside without it being obvious.

I have carbon fibre forks on my Cannondale and I feel safe with them, but I am glad that they have an alloy steerer. It probably doesn't make sense, but I feel better attaching the stem to a metal tube rather than one made of CF.

 

[RecordAceFromNew]

what do you guys think? has he been straight with me (or giant straight with him).

i'm particularly happy with how he told me giant make their cf forks; a swaged end on an alloy steerer tube and then inserted into the machine that bonds the tube to cf & resin, i.e., not cold glued into a crown like a lot of companies used/do.

ribble bikes was one of the companies that was mentioned in the cheap chinese carbon category.

Giant was, is, and has always been a Taiwanese company. They are also one of the largest manufacturers in China.

 

[Noodley]

<bang bang bang> <<<that's my head thumping repeatedly against the keyboard.

 

[PpPete]

CF keyboard by any chance, Noodles ?

 

[snailracer]

Next we know the OP will be warning against flying - all those dangerous weak Al and carbon fibre planes ought to be replaced with steel ones

Who are these mind-bogglingly ignorant people who go on about the 'strength' of a material as if it only comes in one - dangerous - form? I suggest they all move to wood bikes and avoid all technological materials as occasionally some component makes it past the QA test and fails in use. Humans being fallible, it's always going to happen

Are you seriously using flying as an example to promote Al and CF? Aviation has had an inglorious history with both CF and aluminium (although steel has been satisfactory, AFAIK).
If you go through the aviation engineering websites, you will note that there are dozens of types of Al alloy, many more than the 2 or 3 used for bike frames. For each type, the failure characteristics are noted and the particular plane crash where this failure mode was "discovered" is usually mentioned. Gruesome, hard-won knowledge, which steel, with its much longer history, has already acquired.

 

[al-fresco]

I had a steel frame seat tube break once - it was the weirdest feeling - the pedals were in an almost horizontal position and one was touching the ground but I was still trying to pedal! I didn't know what had happened until I got off.

 

[BrumJim]

Are you seriously using flying as an example to promote Al and CF? Aviation has had an inglorious history with both CF and aluminium (although steel has been satisfactory, AFAIK).

I don't think anyone has ever built a steel plane. Not in any reasonable quantities, anyway.

We've learnt a lot about aluminium through aircraft failures, and now can predict failures as well, if not better, than steel.

The thing stopping carbon fibre being used on commercial aircraft has been detecting fatigue failures. I guess from the development of the Dreamliner and A380 that these problems have now been resolved, at least for top end users. There still remains the problem that carbon fibre, in proof loads, fails suddenly and catestropically (brittle failure), whereas steel and alu suffer ductile failures. In fatigue, all these materials fail the same way - suddenly and without warning. Wood is the only material that gives you plenty of warning before collapsing. Bamboo? Not too sure yet.

 

[snailracer]

I don't think anyone has ever built a steel plane. Not in any reasonable quantities, anyway...

Steel is being superseded in planes, but the state-of-the-art 787 Dreamliner still has about 10 tons of steel, compared to 35 tons of CF.
The fuselages of many modern light aircraft are still made of steel frames supporting aluminium panels - steel is still cost-effective if you need to weld parts together.
Some cold-war Soviet warplanes were made almost entirely of steel so they could be mass-produced (and could still fly at mach 3) and are still flying.

...The thing stopping carbon fibre being used on commercial aircraft has been detecting fatigue failures...

CF doesn't suffer from fatigue failures as far as is known. Other, long-term failure modes may exist, nobody really knows for sure.

...We've learnt a lot about aluminium through aircraft failures, and now can predict failures as well, if not better, than steel... I guess from the development of the Dreamliner and A380 that these problems have now been resolved, at least for top end users...

My point wasn't that CF is somehow intrinsically crap, it's that engineers aren't that good at designing/manufacturing with it, and the service & maintenance aspect barely exists for bicycles - how many bike shops have ultrasonic scanners and endoscopes?

Boeing (787 stringers), Airbus (rudder, tail) and Trek (fork steerers) have all had high-profile failures of CF components. CF failure isn't even new - Rolls-Royce tried and failed with CF compressor blades in their jet engines in the 1960's, which was so disasterous the company went broke.

Those companies are the best manufacturers in their respective fields - if they can screw up their CF designs, that suggests to me that CF still isn't quite ready for the mainstream.

...In fatigue, all these materials fail the same way - suddenly and without warning. Wood is the only material that gives you plenty of warning before collapsing. Bamboo? Not too sure yet.

In addition to the CF, the Dreamliner contains about 30 tons of fibreglass (CF's less-pretty composite sister) - a proven, tough material that fails in a non-catastrophic manner.