Does a good carbon frame last longer than Aluminum?

[Acrimony]

I've juz bought a CF framed bike, and asked the question several times regarding life-span of CF and AL, and I was never told that CF would only last 1-2 yrs max.
Does this mean that the frame is rendered 'useless' after this life-span? It seems rather short for a material that is becoming more popular.

I doesn't mean that your CF bike wont be any good after 2 yrs, its just then that the linear degradation of the resin starts to climb more rapidly. And whn i say 2 yrs, i mean 2 yrs of 20000km +, including racing. Chances are you wont notice your frame being feeling any different. If you jumped on a brand new frame of the same model, you might notice a bit of difference. But it is the next 3yrs where the frame really looses its stiffness. And the frame will be pretty useless by about 100000km. AL will actually fatique about the same amount in the first 2 yrs, but in the next 3, it wil fatigue about 1/2 as much as carbon, and assuming its a good frame to start, it should last well beyond 100000km. Steel fatigues at a constant rate, and corrosion is more likely to end the frames life than actually fatigue. And I put the call out to anyone who has done a lot of riding on Campag record carbon cranks, then changed to a new set. I had a set for 2yrs, just bought a new set and thats when you notice the difference. Never noticed the flex creeping in to the cranks, but my new set if visibly alot stiffer.

 

[clack3rz]

I doesn't mean that your CF bike wont be any good after 2 yrs, its just then that the linear degradation of the resin starts to climb more rapidly. And whn i say 2 yrs, i mean 2 yrs of 20000km +, including racing. Chances are you wont notice your frame being feeling any different. If you jumped on a brand new frame of the same model, you might notice a bit of difference. But it is the next 3yrs where the frame really looses its stiffness. And the frame will be pretty useless by about 100000km. AL will actually fatique about the same amount in the first 2 yrs, but in the next 3, it wil fatigue about 1/2 as much as carbon, and assuming its a good frame to start, it should last well beyond 100000km. Steel fatigues at a constant rate, and corrosion is more likely to end the frames life than actually fatigue. And I put the call out to anyone who has done a lot of riding on Campag record carbon cranks, then changed to a new set. I had a set for 2yrs, just bought a new set and thats when you notice the difference. Never noticed the flex creeping in to the cranks, but my new set if visibly alot stiffer.

Thanks for clearing that up a little.
So does usage or time (if the frame was to be left in a garage not used) or both affect the degradation of a frame (albeit CF, AL, Steel)?
I'm now juz curious on the technical side on this so it's now a 'FYI' regarding the degredation timeline.

 

[Acrimony]

Thanks for clearing that up a little.
So does usage or time (if the frame was to be left in a garage not used) or both affect the degradation of a frame (albeit CF, AL, Steel)?
I'm now juz curious on the technical side on this so it's now a 'FYI' regarding the degredation timeline.

Its really just usage, corrosion of the steel aside. UV light will start to break down the resin in carbon (like it fades the decals), but really this effect is pretty minimal and it usually needs a lot of exposure, at worst you might get a slight discoloration of the laqueur (usually goes a bit cloudy) from the resin directly on the surface starting to break down a little, but the effect is really only visual.

 

[clack3rz]

Its really just usage, corrosion of the steel aside. UV light will start to break down the resin in carbon (like it fades the decals), but really this effect is pretty minimal and it usually needs a lot of exposure, at worst you might get a slight discoloration of the laqueur (usually goes a bit cloudy) from the resin directly on the surface starting to break down a little, but the effect is really only visual.

Tks again. I've never 'researched' the lifespan of frames etc. The only reason I bought a CF bike, was because the bike fit/felt right and was in the same price range as AL bikes (it was on special - 06 model). I didn't buy it because it was CF (although the price did sway me slightly, as it also has better components than some of the AL & AL/CF combo's I looked at). So I was a little concerned when reading this post!

 

[Phill P]

Carbon fibre provides virtually all the strength and stiffness to carbon frames, and does not fatigue. Carbon fibre fails in a brittle nature (ie snaps). The resin provides next to nothing other than to hold the carbon in place. If its properties decrease over time I very much doubt anything would happen to the performance of the frame. The only weakness that might occur is bonding between layers, bond quality in lugs may age but I'm not sure on this matter.

Welded steel frames have a fatigue limit where if the loading remains below this limit fatigue failure will not occur, even in welded areas (the weld decreases the fatigue limit). Al does not have this and hence has a reputation for fatigue. Fatigue cracks tend to grow fast as the crack propergates, regaurdless of material.
A fatigue crack may grow in a carbon frame through the plastic, a good reason to lower the void volume, but I would expect crack propergation to be stopped each time it reaches a fibre. If the matrix to fibre bond is strong then the crack will stop there.

If your frame or crank feels soft after a few years, I'm guessing its got more to do with hidden product changes (ie carbon quality or layout) not due to the original carbon structure degregation.

 

[jhuskey]

I did think that this was the case (the life span was alot longer). I don't take forum's advice (and life!) too seriously, but I do (as do many other peeps) use these forums to reference, compare and take advice from others to help them understand, learn more about this topic.
But thanks for the advice

It's just my sytle of over-illustration. I didnt really think you did.

 

[Dietmar]

It's just my sytle of over-illustration. I didnt really think you did.

For the benefit of innocent bystanders to this thread, and to make it abundantly clear: This Acrimony guy does have no clue whatsoever what he is talking about. The best advice is to ignore everything he said. Fiber reinforced materials, including carbon fiber parts, are now commonly used in critical structural component in the aerospace industry, some of them subject to millions and millions of load cycles over projected life spans measured in decades. Of course, the same is true for aluminum and steel.

 

[RickF]

For the benefit of innocent bystanders to this thread, and to make it abundantly clear: This Acrimony guy does have no clue whatsoever what he is talking about. The best advice is to ignore everything he said. Fiber reinforced materials, including carbon fiber parts, are now commonly used in critical structural component in the aerospace industry, some of them subject to millions and millions of load cycles over projected life spans measured in decades. Of course, the same is true for aluminum and steel.

Even if Acrimony was correct (and I agree that he is not), based on his estimated life span and the time I have available to ride, my new carbon fiber bike will last 11 years. In 11 years, I will be 65 years old. I expect that by then, I probably would want a different bike, anyway. I expect that by then, there will be significant improvements in materials and components, and a bike I buy 11 years from now should last me for the remainder of my life (or at least until I am too old to ride anymore). In 11 years, I will have paid off my mortgage, I will have paid off all of my daughters' weddings, all of my children will have been out of college (including graduate and professional school) for many years. I probably could afford a titanium Serotta by then.

 

[Dietmar]

I probably could afford a titanium Serotta by then.

Well, Serotta's top-of-the-line MeiVici is all carbon.
You could probably afford that one, too...

 

[Acrimony]

For the benefit of innocent bystanders to this thread, and to make it abundantly clear: This Acrimony guy does have no clue whatsoever what he is talking about. The best advice is to ignore everything he said. Fiber reinforced materials, including carbon fiber parts, are now commonly used in critical structural component in the aerospace industry, some of them subject to millions and millions of load cycles over projected life spans measured in decades. Of course, the same is true for aluminum and steel.

Maybe you should actually look at the application of CF in the aerospace industry. When it is actually used as a structural material, it is almost always used where there are no compressive or torsional forces, and generally designed to be easily replacable. Carbon monocot frame structures in the aerospace industry are not unheard of, but so far very rare and usually used on milatary and test aircrafts, where cost is not a factor. The same goes for formula 1, yes they use is for structural elements including active suspension links, but how often is it replaced? I'm not saying that CF is useless, I just syaing that CF still has its limitations, just as steel and AL do, and its impact resistance and fatigue life are the two main concerns. I think the main problem in the bike industry, and the same goes for AL, is the frame builders endless pursuit of lighter frames, which is generally achieved by removing material and sacrificing the life span of the frame. Guess i'll just have to wait another 5 yrs and see how all these sub 1kg frames feel.

 

[jhuskey]

For the benefit of innocent bystanders to this thread, and to make it abundantly clear: This Acrimony guy does have no clue whatsoever what he is talking about. The best advice is to ignore everything he said. Fiber reinforced materials, including carbon fiber parts, are now commonly used in critical structural component in the aerospace industry, some of them subject to millions and millions of load cycles over projected life spans measured in decades. Of course, the same is true for aluminum and steel.

Damn! Where were you yesterday I traded by CF bike in for a soild Steel Mongoose.
Oh well,screwed again.

 

[JohnO]

I've juz bought a CF framed bike, and asked the question several times regarding life-span of CF and AL, and I was never told that CF would only last 1-2 yrs max.
Does this mean that the frame is rendered 'useless' after this life-span? It seems rather short for a material that is becoming more popular.

Interesting... I have ridden the same CF frameset for the last four years, and it hasn't become the least bit noodly. Still as stiff as day one, still has that smooth ride.

 

[bobbyOCR]

Interesting... I have ridden the same CF frameset for the last four years, and it hasn't become the least bit noodly. Still as stiff as day one, still has that smooth ride.

An interesting study in Bicycling Australia (referenced from other studies) did actually state that carbon fibre does lose stiffness. Under one test setup, the frame retained the majority of its initial stiffness until 2/3 of its fatigue limit. At 90% of its fatigue limit, it retained only 10% of its initial stiffness. Under other test conditions, it's stiffness decreased in a linear fashion. at 50% of its fatigue limit, it retained 50% stiffness. These tests are quite interesting to note, as if a bike has a fatigue limit of 9 years, it would be raceable for 6 until stiffness loss was felt. BUT. In that 6 years it is very likely that the frame would have been superceded and replaced by a better one. So whether the test applies to an individual depends on circumstances.

 

[Bro Deal]

An interesting study in Bicycling Australia (referenced from other studies) did actually state that carbon fibre does lose stiffness. Under one test setup, the frame retained the majority of its initial stiffness until 2/3 of its fatigue limit. At 90% of its fatigue limit, it retained only 10% of its initial stiffness. Under other test conditions, it's stiffness decreased in a linear fashion. at 50% of its fatigue limit, it retained 50% stiffness. These tests are quite interesting to note, as if a bike has a fatigue limit of 9 years, it would be raceable for 6 until stiffness loss was felt. BUT. In that 6 years it is very likely that the frame would have been superceded and replaced by a better one. So whether the test applies to an individual depends on circumstances.

I am glad I ride titanium. When all you guys' frames are being recycled into plastic milk jugs, I'll still be rockin' down the road.

 

[bobbyOCR]

I am glad I ride titanium. When all you guys' frames are being recycled into plastic milk jugs, I'll still be rockin' down the road.

lol. The magic metal. I want one but there is no chance I will get one. If you want to see a very nice kindof retro styled titanium&carbon frame look at the pedalforce fusion and don't underestimate them, as their QS2 is the Litespeed Pavia without paint, and at half the cost (or less)

 

[dhk2]

I am glad I ride titanium. When all you guys' frames are being recycled into plastic milk jugs, I'll still be rockin' down the road.

??? Surely you know that Ti frames fatigue and break just like everything else does. A hammerhead racer here has busted a couple of Ti frames, as well as steel, CF, AL.
Believe the german EFBE website has some data on the relatively poor fatigue performance of several Ti frames they tested. There also used to be a photo of a Merlin frame which had a downtube failure early in the test cycle.

Another racer I know has gotten two replacement 5200 frames before Trek cut him off of the "free frames for life: program. He's not racing or training 12K miles a year now, happily riding frame number 3, and still likes CF Treks a lot.

Not saying Ti is bad, just that strong racers break everything. Personally, hope I continue to ride long enough and hard enough to break my custom AL/CF bike someday. If it's good for 30-50K miles, at 5K miles a year, may never get there.

 

[Bro Deal]

??? Surely you know that Ti frames fatigue and break just like everything else does.

I was being facetious, but titanium just like steel has a fatigue limit. Loads below the limit will not cause fatigue failure no matter how many cycles are applied. Aluminum on the other hand has no fatigue limit and will eventually fail no matter how small the loads are. This means exactly bupkiss in practice because frames are designed to account for the material they are constructed out of. You should not experience fatigue failure if the frame maker did his job right, but in practice everything eventually breaks one way or another if you use it enough.

There have been frame makers that have sold frames meant for a single season of racing. Ritchey comes to mind as does a couple Italian manufacturers using aluminum. Off the top of my head I cannot think of any company doing this today; the customer support for people who did not heed the warnings, bought just because of low weight, and then complained when the frame broke must have been nightmarish.

Any frame you buy is likely to be over engineered whether it is made from steel, carbon, aluminum, or titanium. The companies have lawsuits to think about; and maybe even more importantly, they have to think about the damage to their brand if their frames were to regularily fail.

The most likely way a frame will fail is crashing and after that comes manufacturing defects, but defects are a low probability failure mode compared to crashing. You cannot do anything about crashing, but manufacturing defects come down to the the skill and quality of the frame maker, which is far, far more important than what material is used.

As far as Al vs. C I don't think it matters. Welded aluminum frames have been around since Gary Klein first started making them in the mid 70s. Al frames have stood the test of time. Older carbon frames were notorious for tube separation, but that was from manufacturers like Trek that were just getting into making things from carbon. Craig Calfee has been making carbon frames since the late eighties and has always had extremely low return rates. Now that even the low budget manufacturers have dialed in carbon frame making, you can count on a carbon frame lasting a long time. Perhaps if you want to be riding the same frame in 2020 it might matter, but for more realistic terms of use it is not likely to make a difference.

 

[dhk2]

Yeah, you fooled me with your facetious claim about ti never failing. Agree with the points you make in your serious summary.

Speaking of short-life frames, Cannondale has a good caution note as a supplement to their CAAD 7 and Optimo frame manuals. It clearly states that these frames are designed as light and as stiff as possible to win races, not last forever. Also states they will have a short life when ridden by aggressive racers, but last longer for normal riders. Also warns that the thinwall tubing can be easily dinged in normal handling accidents which could lead to early failure.

Have to applaud C'dale for being so upfront about the trade-off of weight vs strength. Believe it shows their confidence as an industry leader in high-quality frames. Would be good if the LBS dealers were as candid with customers walking in the door to purchase the latest 16 lb wonderbike.