This is a question I've been asking for a while, I've never really been able to find a satisfactory answer, however fortunately GCN have done a great video talking to a couple of people who know what they're talking about and answered it really well:
What's the answer?
It doesn't give an exact time frame or number of cycles before failure like you do with, say, aluminium, but it definitely gives you a rough idea of what to expect! And, perhaps most usefully from a safety point of view, it does suggest that you might get some warning before you get a catastrophic failure
What’s the answer?
Short answer: Yes
Longer answer: everything does eventually
Longest answer: watch the video
Meh, don't like videos.
If I did, I'd be on YouTube not a forum
Fair enough!
One of the intetesting implications is that, if could bear the thought of a carbon fibre frame weighing the same as an aluminium or even steel frame then it could, possibly, pretty much last forever. As the second guy says 'give an engineer a stronger material and they will put more stress on it' lol
Meh, don’t like videos.
If I did, I’d be on YouTube not a forum
Agreed. I like something I can read, with a few short videos to illustrate something that requires a moving image.
Pah, got 32 years and going strong out of my Columbus SLX race bike from 1990
without watching the video I would guess that a frame with a higher carbon to resin ratio will last longer than a cheaper one, as it is the resin which will degrade over time with sun exposure etc. But I expect even that is minimal and gradual
Yep, they do mention that not all carbon frames are equal- and that that plays a huge part in how long they will last. UV exposure is also a factor, but the largest one by far is how much torsional force is being put through the frame. For example Mark Cavendish will have significantly fatigued his frame by the end of the season, whereas a mere mortal going for non-competitive weekend rides could get many years out of a frame
Do components made of Carbon fatigue?
Strange question.
Perhaps better to consider, what are the risk/rewards to using Carbon components.
IMO, the rewards of employing Carbon are out-weighed by the risks when your Carbon whatever, fails.
YMMV.
The question is sensible enough - it just happens to be the risk question (or one of them).
Nope, do any of us really " NEED " carbon? Nope!
Most of you are too fat to benefit from the marginal weight saving.
It's a whizzing contest for those who are more easily parted from their money than their spare tyre.
can't be arsed watching another GCN fluff video
I'm guessing they "discovered" that the epoxy holding the carbon together isn't infinitely duravle and is susceptible to weathering, especially degradation by UV, or the more you clatter about on rough terrain or heave on it in sprints...
That about the size of it?
I bet it was a sponsored video ?
…..and in next weeks GCN video, are round wheels better than square ? Stay tuned
To be fair I have enjoyed a few of the more documentary style GCN vids
I’m more interested in what Bombardier think about the question.
When my Father in Law (long gone) raced and engineered motorbikes when titanium came on the scene, bolts had to have a date on them and be replaced by a certain time. There was a similar commotion about aluminium, my MTB frame 22 years old now. I did speak to someone a while ago who worked with military helicopters though and they were having problems with the carbon fibre models as the engines were squashing the bodies when they landed!
It's a good Q, there does seem to be a perception that carbon doesn't fatigue like metals can and since there's no welds to crack.
As I understand it (I'm no composites expert at all) some of the 'fatigue' is related to voids and imperfections and where they are, how many etc. Carbon products in the bike industry will have voids and wrinkles to some extent because they're made to a cost, they're made to suit Industrial Design shapes, they're made to stupid shapes that don't suit hand lay-up productions and can't be compressed well, etc.
Those voids are areas where the carbon fibre doesn't handle loads as intended, the 'layers' or the outer edges of a void can move relative to each other and cause delamination at the edges which spreads. Again, depends how much and where. It happens faster when the loads are higher so in that way it's similar to metal fatigue.
Exactly. As per the video, carbon 'fatigues' in a different way to any of the metal alloys used in frame building, but will still degrade over time. The degradation depends on quality of initial manufacturing, exposure to UV, water ingress and most importantly the amount of stress applied when riding, crashing etc
This ^^
The Bombardier wing article summarises it, “What’s more, composites have superior fatigue performance to aluminium.”
But how many bike frames are built to the standards of an aircraft wing and regularly inspected to the standards of an aircraft wing?
Therein lies the problem
Yeah, but aluminium bike frames aren't built or tested to that standard either
Aluminium frames are a simpler and more consistent manufacturing process though, assuming your basic set up for production is accurate your frames will be consistent to tested samples - human error could still cause problems but robot welding is possible and bad welds are pretty easy to check for visually. Carbon production has a lot of room for error and variation in a batch and it's harder to spot. (edit - or more time consuming and expensive to spot rather than harder)
Aluminium frames are a simpler and more consistent manufacturing process though, assuming your basic set up for production is accurate your frames will be consistent to tested samples – human error could still cause problems but robot welding is possible and bad welds are pretty easy to check for visually. Carbon production has a lot of room for error and variation in a batch and it’s harder to spot. (edit – or more time consuming and expensive to spot rather than harder)
You're comparing apples and ferrets really, welded metallic structures are a world away from laminated composites. Flaws in either can be as hard to detect and various NDT techniques can be used on either. Case in point I was presented with a bit of Aluminium that had fallen off of another part on the shop floor yesterday, said part was allegedly welded by a coded welder and Dye pen inspected, there was close to zero penetration, evident from the snapped off face.
It's about as easy to do a shite weld as it is to leave voids in a laminate. The trick in either instance is detecting a flaw.
Most of the arguments above against carbon fibre are even more applicable to aluminium or steel components -
Titanium of course if 'for life' 😉
Corrosion is a factor for me in frame choice.
It’s all a bit academic as I will have decided I want a new frame long long long before the frame gets even half way to the fatigue life of it what ever its made of
@cookeaa Totally different, yes and not saying Al is easy. My take on carbon being harder is based on how small an imperfection in carbon can cause a sudden failure and how hidden that flaw can be or how much time is needed to find it. Small weld defects may well cause a failure and be hard to spot but defects like that don't usually fail as fast or as catastrophically as carbon, the kind of defect likely to cause that sort of fast failure in Al being easier to see signs of. For a start you focus on the joins, not the entire frame or fork. That's from what I've seen not being a test engineer oc. A danger of being a generalist is generalisations..
The Boeing 787 uses carbon fibre panels for the skin of its wings, they flex a lot in flight and they'll be designed for a decent service life as plane wings aren't cheap to replace....
I listened to the whole video and it seems more concerned with road bikes than mtbs (I guess that's down to the YT channel it's on) - things that would be more concerning for us MTBers (I think there are 1 or 2 on here) would be how it fatigues around pivot points and for eBikes, have they made it strong enough to cope with those extra stresses... but then, as said above, how long do people really keep their bikes and is that, in reality, a tiny window of the actual shelf life of the carbon?
timba
The Bombardier wing article summarises it, “What’s more, composites have superior fatigue performance to aluminium.”
But how many bike frames are built to the standards of an aircraft wing and regularly inspected to the standards of an aircraft wing?
Therein lies the problem
Edit: Originaly replied to wrong quote
Hope bike frames may go somewhere towards those standards. Most folks probably already know the connection with Rolls Royce i.e. The Hope founders were ex RR engineers from the RR plant in Barnoldswick. When I had a look around the Hope factory I was told that when they went into frame manufacture they drafted in some RR carbon fibre experts to teach them how to do it. So they should be pretty much as good as it gets.
The part needs to be not only laid up correctly, but also designed correctly.
Working in the composite industry, the variance of lay-ups and the predicted life cycles of parts vary greatly. F1 parts that need to last a race vs safety critical aircraft parts vs body panels for supercars... all can fail prematurely if laid up incorrectly, not consolidated correctly and ultimately not designed properly.
Most carbon will be painted with a UV stable clear coat (if showing raw weave) or by paint, so i wouldnt worry about UV damage.
Most carbon lay-up is still a human process, so it can have inconsistencies, therefore failure can happen from time to time, but its most likely the part has been poorly made, somehow got through QC and broke during hard use, rather than years of fatigue.
My Norco Optic frame failed, but it was the glue that held a carbon sleeve into a carbon frame that failed, not the carbon itself. Its pretty hardy stuff!
chrismac
Full MemberIt’s all a bit academic as I will have decided I want a new frame long long long before the frame gets even half way to the fatigue life of it what ever its made of
Got to agree
I had a literally ‘state of the art’ carbon road bike in 2012 (sadly stolen) but compared to my current, far less top end, road bike now it was lacking in lots of areas.