Life of carbon frames

Simmo
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Life of carbon frames

Postby Simmo » Fri Feb 02, 2018 7:55 pm

My high end carbon road bike has now done 25,000 kms in the 5 years I've owned it. What sort of life should I expect from it before (a) having it checked over by a carbon specialist (x-rayed?) and (b) replacing the bike altogether.

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Tim
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Re: Life of carbon frames

Postby Tim » Fri Feb 02, 2018 8:30 pm

Don't worry about it.
If it hasn't cracked yet it probably won't in the future. Unless you crash it.
Any of the broken carbon frames I've seen have cracked within the first year or two, including one of my own.
Who X-rays bike frames as a routine maintenance item?
Wait till it's 30 years old or clocks 200,000km's. I'm being serious.

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AUbicycles
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Re: Life of carbon frames

Postby AUbicycles » Fri Feb 02, 2018 10:39 pm

In theory it will last forever. But this refers to the carbon itself whereas the resin is the 'unknown' factor. The carbon itself doesn't get tired and fatigue as an alloy does over time and in use. Degradation or fading from UV exposure is a problem of the resin but it would take a Carbon Fiber expert to contribute as to whether or how it may affect structural integrity. It is still early days in carbon fiber bike product that trends of long-term use and lifespan is open - but you can still spot some of the early adopting brands that used just tubes or the complete track bikes that are still completly structurally sound.

As carbon fiber on a bike is usually built to flex in certain areas, particularly on the seat and chain stays this can result in surface cracks of the paint / coating (e.g at the Bottom bracket joint and other connection points) which don't actually affect the integrity of the frame. The superficial cracks can appear at any time.

For some peace of mind, bike manufactures typically overcompensate (that is another debate in itself). Unless that series of bikes have already displayed a tendency to fail during to design flaws or production flaws - as Tim has suggested, you can ride until the cows come home.

But if you want a new bike... the rule is n+1

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Re: Life of carbon frames

Postby mjbmikeb2 » Sun Feb 04, 2018 8:25 pm

A cheap diagnostic test you can do yourself is to brush on some fluorescent crack detection dye, wipe off then inspect with a UV light.
You can buy the proper stuff from engineering suppliers, or if you want to be really cheap, squeeze out the dye from a $2 invisible ink security marker pen and use the built in LED to inspect for cracks.

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Re: Life of carbon frames

Postby AUbicycles » Mon Feb 05, 2018 2:19 am

@mjbmikeb2 - good idea, thanks for sharing. I am sure this would pick up superficial cracks, though am wondering if this can help locating and identifying more serious fractures.

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Re: Life of carbon frames

Postby Comedian » Mon Feb 05, 2018 6:23 pm

AUbicycles wrote:@mjbmikeb2 - good idea, thanks for sharing. I am sure this would pick up superficial cracks, though am wondering if this can help locating and identifying more serious fractures.

Yes, wouldn't work for interior de-lamination. That's why people use ultrasonic and x-ray testing. It's also worth noting that superficial cracks can cause damage into the lower layers if left over time.

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Re: Life of carbon frames

Postby robbo mcs » Mon Feb 05, 2018 8:10 pm

Interesting article on ageing parts. Raises lots of questions, but doesn't really answer them

http://www.smh.com.au/business/consumer-affairs/should-there-be-a-safe-life-for-bicycle-parts-20161117-gss41s.html

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Re: Life of carbon frames

Postby Comedian » Tue Feb 06, 2018 2:14 pm

robbo mcs wrote:Interesting article on ageing parts. Raises lots of questions, but doesn't really answer them

http://www.smh.com.au/business/consumer-affairs/should-there-be-a-safe-life-for-bicycle-parts-20161117-gss41s.html

That's a very interesting article. To me what I found interesting was that he basically made the same points that I have made in here before. Yes, composite aircraft parts last the life of the airframe but bikes aren't planes...

However, Peter Bourke, general manager of Bicycle Industries Australia, said it would be near-impossible to replicate that same standard with a bicycle.

"In the aerospace industry every use of every part is documented. There is no control over how the bicycle is treated, how the bicycle is used, how the bicycle is stored, how the bicycle is transported," Mr Bourke said.

"There are so many variables it is actually very hard to identify a safe life of a part of a bike."


That's why personally I think CF isn't an ideal material for bikes - but clearly it's good enough if you either don't do many miles or change your bikes pretty regularly. It's probably the ultimate material if you can just grab another one out of the sponsors truck if you break one.

CF just doesn't perform well with impacts and they are just part of being a bike. A mate has a high mileage (35k) specialized which had a chain break and turn and heavily "munge" the BB area. A little while later he picked up a piece of wire in the spokes which scratched up the inside seat stay pretty badly. He's thinking he'll write it off .. another one for landfill.

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Re: Life of carbon frames

Postby duncanm » Tue Feb 06, 2018 4:51 pm

robbo mcs wrote:Interesting article on ageing parts. Raises lots of questions, but doesn't really answer them

http://www.smh.com.au/business/consumer-affairs/should-there-be-a-safe-life-for-bicycle-parts-20161117-gss41s.html


This, I'm afraid, demonstrates a fundamental flaw in our coronial inquiry system

The coroner always feels like she has to recommend something, anything; no matter how impractical or useless; when in reality, what occurred was a tragic accident that could not (reasonably) have been prevented.

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Re: Life of carbon frames

Postby duncanm » Tue Feb 06, 2018 5:00 pm

AUbicycles wrote: Degradation or fading from UV exposure is a problem of the resin but it would take a Carbon Fiber expert to contribute as to whether or how it may affect structural integrity. It is still early days in carbon fiber bike product that trends of long-term use and lifespan is open .


Life of resins in high UV environments (think carbon masts on yachts, exposed 24/7) is certainly well understood.

Damage to epoxy from UV exposure is easily mitigated by the appropriate clear coat or paint.

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Re: Life of carbon frames

Postby Comedian » Tue Feb 06, 2018 6:34 pm

duncanm wrote:
AUbicycles wrote: Degradation or fading from UV exposure is a problem of the resin but it would take a Carbon Fiber expert to contribute as to whether or how it may affect structural integrity. It is still early days in carbon fiber bike product that trends of long-term use and lifespan is open .


Life of resins in high UV environments (think carbon masts on yachts, exposed 24/7) is certainly well understood.

Damage to epoxy from UV exposure is easily mitigated by the appropriate clear coat or paint.


The issue that we have to watch with this kind of thing is that the UV in QLD is vastly different to the UV in other parts of the world. It's in another realm worse..

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Re: Life of carbon frames

Postby duncanm » Tue Feb 06, 2018 9:54 pm

Comedian wrote:
duncanm wrote:
AUbicycles wrote: Degradation or fading from UV exposure is a problem of the resin but it would take a Carbon Fiber expert to contribute as to whether or how it may affect structural integrity. It is still early days in carbon fiber bike product that trends of long-term use and lifespan is open .


Life of resins in high UV environments (think carbon masts on yachts, exposed 24/7) is certainly well understood.

Damage to epoxy from UV exposure is easily mitigated by the appropriate clear coat or paint.


The issue that we have to watch with this kind of thing is that the UV in QLD is vastly different to the UV in other parts of the world. It's in another realm worse..


you're right - no boats in Qld. ;)

Just don't leave your raw carbon bike out in the sun all year.. and if you like the carbon look, make sure its sprayed with a proper UV blocking clear coat.

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Re: Life of carbon frames

Postby Toyopet » Tue Feb 06, 2018 10:52 pm

Will a carbon frame degrade faster over time compared to other materials?.... I don't know.
But if a carbon frame is stronger to begin with (compared to other materials) I guess it should at least be stronger in the long term.

I always go back to this video, comparing the strength of the same frame made from two different materials.
https://www.pinkbike.com/video/243228/

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Re: Life of carbon frames

Postby AUbicycles » Wed Feb 07, 2018 12:10 am

duncanm wrote:Just don't leave your raw carbon bike out in the sun all year.. and if you like the carbon look, make sure its sprayed with a proper UV blocking clear coat.


How can you be sure? They discovered that they needed UV stabilisers and both the resins can be stabilised and the correct clear coat used to protect the resin from UV degradation. As a rider you can hope (or even expect) the bike to be protected... and with the big brands it should, but on the other hand you can't be entirely sure.


Toyopet wrote:Will a carbon frame degrade faster over time compared to other materials?.... I don't know.
But if a carbon frame is stronger to begin with (compared to other materials) I guess it should at least be stronger in the long term.


Carbon frames are designed to be strong/stiff in certain direction and compliant in others. This all comes back to the carbon layup and the selection and combination of the weaves. This also means there will be big differences between series. As an example, top-end bike moulds can end up as the mould for the mid-range and then lower-range carbon fiber bikes however the layup and material selection also typically changes.

It means that I expect to see a lot of differences in the actual lifespan of carbon fiber bikes whereas an alloy bike provides a bit more clarity if you know the alloy grade along with a visual inspection.

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Re: Life of carbon frames

Postby Comedian » Wed Feb 07, 2018 7:48 am

AUbicycles wrote:
duncanm wrote:Just don't leave your raw carbon bike out in the sun all year.. and if you like the carbon look, make sure its sprayed with a proper UV blocking clear coat.


How can you be sure? They discovered that they needed UV stabilisers and both the resins can be stabilised and the correct clear coat used to protect the resin from UV degradation. As a rider you can hope (or even expect) the bike to be protected... and with the big brands it should, but on the other hand you can't be entirely sure.



Exactly! What if the bike you get is tested in Europe? What if the UV coatings are fine there? I've got a number of cycling products made by big brands that can't hack the UV in QLD.

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Re: Life of carbon frames

Postby Kronos » Wed Feb 07, 2018 8:19 am

One of the common themes I've seen as carbon is designed to flex, it's generally designed to flex in one direction. What happens when it flexes in the other direction? It tends to snap or crack. Modern frames have a lifetime guarantee but that lifetime may be expended when you crash. It's a catch 22 situation. Carbon is kind of great, until its not. It's strong but its also not strong.

Carbon is also brittle and suffers from over tightening fatigue like anything, it's not a wonder material in this sense either. Watch what happens when some gorilla over tightens a clamp on a particular part of your frame, bars, seat post, etc... from not using a toque wrench. The carbon will generally crack at the point because of over tightening. This type of issue doesn't generally affect alloys (they bend before they snap.) This is before we talk about what happens when we drop carbon in any sort of reasonable speed crash. It breaks and becomes cost ineffective to repair alloys generally can be repaired although its not generally best to reheat aluminum repeatedly.

The short and the long of it is that this "isn't an I hate carbon" post. I see lots of value in carbon bikes, although I don't currently own one (personal choices I've gone back to steel and aluminum) I'm not being a retro grouch either. What I am saying is this:

Carbon is prone to brittle and stress failures, it isn't some wonder material.

The problem with unidirectional tests is that they don't represent the forces of reality. When was the last time you excreted force in one direction when you crashed? Alloys have the weaker maximum strength yield overall, but the problem as a post explains on the video above is that alloy will handle mostly everything, its a good all round material that is as strong as you need it to be in all directions that force can be excerpted. It is the good all around material. On top of that a failure on a carbon bike is likely to be catastrophic a failure in alloy composites (steel/aluminum) a failure is likely lead to a bent component but not a catastrophic failure. Herein lies point number two:

A failure in an alloy bike generally leads to a bike that is still ridable in a crash (into rocks, off road, potholes, off ledges, etc..) A catastrophic failure on a carbon bike in the same situation may cost you your life. How often do we see a bike that is a complete write off after just one reasonable speed crash on a carbon bike? The steel or aluminum bike will generally survive and can also be repaired cost effectively.

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Re: Life of carbon frames

Postby AUbicycles » Wed Feb 07, 2018 8:50 am

Aluminium alloy however is not that awesome... it can be formed nicely however naturally fatigues and when damaged immediately looses a lot of its strength. Steel has the upperhand. I don’t know enough about titanium however to understand how it compares.

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Re: Life of carbon frames

Postby Kronos » Wed Feb 07, 2018 9:07 am

The general point of fatigue with alloy tends to be at the point of a weld rather than at any point of a tube itself. Yes aluminum has a memory. Constant abuse of a single point as we've seen in the video will lead to a failure. The problem is that, that test doesn't represent reality any more than testing carbon in the same sense. I like carbon on race bikes, but I still prefer to ride aluminum or steel on the road.

Putting all things aside, ride whichever bike you think suits yourself, but all bikes have a finite limit, particularly from crashes or abuse. The problem is if you're going to go out and crash a bike, I would suspect it would generally be safer and more survivable on an alloy bike off the top of my head, but I could be wrong and sometimes am wrong.

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Re: Life of carbon frames

Postby duncanm » Wed Feb 07, 2018 10:21 pm

AUbicycles wrote:How can you be sure? They discovered that they needed UV stabilisers and both the resins can be stabilised and the correct clear coat used to protect the resin from UV degradation. As a rider you can hope (or even expect) the bike to be protected... and with the big brands it should, but on the other hand you can't be entirely sure.
...

It means that I expect to see a lot of differences in the actual lifespan of carbon fiber bikes whereas an alloy bike provides a bit more clarity if you know the alloy grade along with a visual inspection.


I'm struggling to see the difference here.

If you're really concerned about the lifespan of your carbon bike, then buy one that's painted (not clear coat).

btw - UV degradation of both clear-coat and epoxy is fairly obvious upon visual inspection.

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Re: Life of carbon frames

Postby AUbicycles » Thu Feb 08, 2018 7:52 am

duncanm wrote:I'm struggling to see the difference here.

If you're really concerned about the lifespan of your carbon bike, then buy one that's painted (not clear coat).

btw - UV degradation of both clear-coat and epoxy is fairly obvious upon visual inspection.


It is an interesting debate and I think the verdict is still out. My white painted carbon fiber bike is fading/yellowing - is it the clear coat or is it the paint? How much protection does the paint offer. Can my bike be compared with my neighbours bike... a different brand, same age white but no fading?

I am expecting that a lot more carbon fiber bikes enter the second hand market so for the buyers there is far more uncertainty about the integrity... alloy is far simpler to judge.

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Re: Life of carbon frames

Postby RonK » Thu Feb 08, 2018 10:34 am

Comedian wrote:
AUbicycles wrote:
duncanm wrote:Just don't leave your raw carbon bike out in the sun all year.. and if you like the carbon look, make sure its sprayed with a proper UV blocking clear coat.


How can you be sure? They discovered that they needed UV stabilisers and both the resins can be stabilised and the correct clear coat used to protect the resin from UV degradation. As a rider you can hope (or even expect) the bike to be protected... and with the big brands it should, but on the other hand you can't be entirely sure.



Exactly! What if the bike you get is tested in Europe? What if the UV coatings are fine there? I've got a number of cycling products made by big brands that can't hack the UV in QLD.

I think you are are overstating the UV issue. How much time is a bike actually exposed to high levels of UV radiation? Not very much unless you permanently park it outside.

As a Brisbane resident myself, most of my rides take place in the early morning (as is the custom amongst most serious cyclists here), and the longest are done in around 3 hours max, so the bike is usually back in the garage by 9 am, well before UV levels have become significant.
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Re: Life of carbon frames

Postby duncanm » Thu Feb 08, 2018 11:47 am

I'm not going to keep banging on about this beyond this post.. we seem to be going around in circles.

- Carbon (including clear-coated) in 24/7 high-UV exposure conditions has a long history in other applications. Yachting, wind turbine blades, aero, etc
- in the yachting industry, there's well established practices for inspecting and re-coating UV-affected clear coat & carbon
- inspection for UV damage is simple and effective.
- even when UV damage to epoxy is visible, loss of strength of the composite structure is in the single-digit %

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Re: Life of carbon frames

Postby Comedian » Thu Feb 08, 2018 1:38 pm

RonK wrote:
Comedian wrote:
AUbicycles wrote:
How can you be sure? They discovered that they needed UV stabilisers and both the resins can be stabilised and the correct clear coat used to protect the resin from UV degradation. As a rider you can hope (or even expect) the bike to be protected... and with the big brands it should, but on the other hand you can't be entirely sure.



Exactly! What if the bike you get is tested in Europe? What if the UV coatings are fine there? I've got a number of cycling products made by big brands that can't hack the UV in QLD.

I think you are are overstating the UV issue. How much time is a bike actually exposed to high levels of UV radiation? Not very much unless you permanently park it outside.

As a Brisbane resident myself, most of my rides take place in the early morning (as is the custom amongst most serious cyclists here), and the longest are done in around 3 hours max, so the bike is usually back in the garage by 9 am, well before UV levels have become significant.

Interesting. I agree with you.. I certainly try and get my rides done early. However I have seem to have this problem where big name european shorts fade and fall apart in an absurdly short time frame. They go white everywhere that isn't covered. I've seen other people around with the same problem, yet I've never heard of it happening further south.. Anyway.. maybe the UV coatings on frames are up to it these days. Certainly you see yachts and the like out in more UV.. I guess it just comes back to whether your frame has been coated and if the coating itself is durable. Some paints have specify that their UV protection only lasts 12 months .. others a lifetime.

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Re: Life of carbon frames

Postby RonK » Thu Feb 08, 2018 2:32 pm

Comedian wrote:
RonK wrote:
Comedian wrote:
Exactly! What if the bike you get is tested in Europe? What if the UV coatings are fine there? I've got a number of cycling products made by big brands that can't hack the UV in QLD.

I think you are are overstating the UV issue. How much time is a bike actually exposed to high levels of UV radiation? Not very much unless you permanently park it outside.

As a Brisbane resident myself, most of my rides take place in the early morning (as is the custom amongst most serious cyclists here), and the longest are done in around 3 hours max, so the bike is usually back in the garage by 9 am, well before UV levels have become significant.

Interesting. I agree with you.. I certainly try and get my rides done early. However I have seem to have this problem where big name european shorts fade and fall apart in an absurdly short time frame. They go white everywhere that isn't covered. I've seen other people around with the same problem, yet I've never heard of it happening further south.. Anyway.. maybe the UV coatings on frames are up to it these days. Certainly you see yachts and the like out in more UV.. I guess it just comes back to whether your frame has been coated and if the coating itself is durable. Some paints have specify that their UV protection only lasts 12 months .. others a lifetime.

Perhaps it's the way you wash your shorts. But my ASSOS shorts have lasted for quite a few years despite being subjected to commercial washing machines and dryers while touring. They have certainly faded from black but to a brownish black, not at all white.
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Re: Life of carbon frames

Postby Comedian » Thu Feb 08, 2018 3:03 pm

RonK wrote:Perhaps it's the way you wash your shorts. But my ASSOS shorts have lasted for quite a few years despite being subjected to commercial washing machines and dryers while touring. They have certainly faded from black but to a brownish black, not at all white.


Well it's only the bits that aren't covered by my jersey that have faded, and I wash the top and bottom at the same time. :lol:

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