Does Carbon last?

halffattony

Will a carbon frame last as long as an aluminium frame or does it go brittle like plastic,does it deteriate in any other way?

cooldad

I read on the internet they dissolve in the rain.

njee20

No reason for them not to last as long or longer, but like aluminium frames not all carbon frames are the same.

There's no inherent reason for carbon frames not to last a very long time.

coulddobetter

I hope so as I have one .

homers_double

Show off.

ScareyJ

Probably wouldn't have a CF mountain bike frame, But looking at a planet X bike at the moment, How does the stuff Fair when you crash?

homers_double

Santa Cruz had a video somewhere of some destructive tests on a carbon V10 and an aluminium version, the carbon one took some pretty big hits when the alu version just crumpled.

stubs

I read an article in one of the bike mags about carbon frames. Apparently Steel and Alu frames have finite fatigue lives they will eventually fail, it might be decades but they will crack eventually. Carbon and Titanium have infinite fatigue lives and theoretically as long as they arent subject to massive stress that they arent designed for will last forever. The article also said if a carbon frame has a fault it will fail very early on, if its been okay for a year it will be okay for the life of the frame. Carbon frames do break but so does any frame material if a bike was guaranteed not to fail it would weigh as much as an anvil.

I have a carbon H/T and on its 2nd ride I dropped it and it whacked into a rock I though shit thats the frame dented, when checked all I could see was an almost invisible surface scuff on the top coat that might have been from the strap that held the bike in the rack. A mate is keen on canoeing and he has been using carbon paddles for years and they are covered in gouges, scrapes and dings and he reckons they are as good as new. He has repaired paddles and canoes with fibre and epoxy resin and reckons if I bust my frame he could repair it for me. Hopefully I wont be taking him up on his offer.

rockmonkeysc

Depending on the quality of carbon used it can degrade in UV light but it's fine in rain so nothing to worry about in the UK.

slickmouse

halffattony wrote:

Will a carbon frame last as long as an aluminium frame or does it go brittle like plastic,does it deteriate in any other way?

its a BIT of a trick question, ali will last for many thousands of years if you stop it oxidizing, your frame could be around when the sun explodes and swallows the earth ?

if you mean in use, well that depends on the relative quality of the ali and carbon frame in question, ''pure'' carbon fiber is VERY light, VERY stiff and VERY strong and those advantages are also its Achilles heel, as it wont flex, it has no0 alternative than to break if the load is sufficient.

but pure carbon fibre is not what you get, you get a carbon based polymer where other things are mixed in to change the qualities and characteristics. Do you remember REd bull racing and their amazing flexible front wing a couple of years ago, then its even more down to whats mixed in there for what reason and how much it costs to make

mpie

halffattony wrote:

Will a carbon frame last as long as an aluminium frame or does it go brittle like plastic,does it deteriate in any other way?

Putting aside any theoretical issues, I don't think I've ever heard of a frame failing due to 'fatigue' or 'age'. You'll fail (through fatigue or age) before they will (unless you crash, but that's another story).

morepower

RockmonkeySC wrote:

Depending on the quality of carbon used it can degrade in UV light but it's fine in rain so nothing to worry about in the UK.

This is correct. UV light attacks the epoxy resin that binds the carbon together. Once it is coated with a UV stable lacquer or a paint it will last a very long time. I make some Pre-preg parts and I spray them all with a coat of lacquer and it stops them discolouring as well as degrading..

Daz555

http://www.youtube.com/watch?v=6APhKvaW6ig

thelonegroover

From a chemical point of view, polyester degrades due to water but this doesn’t stop it being used very successfully for waterproofs and tents etc.

morepower

Thelonegroover wrote:

From a chemical point of view, polyester degrades due to water but this doesn’t stop it being used very successfully for waterproofs and tents etc.

Bike frames are made from a pre-preg carbon which does not use a polyester resin. The resin is not suited to the process used due to the cure times so epoxy is used. Epoxy resins also "wet out" the carbon better so you have less resin and more carbon pound for pound. Resin has very little strength so the more carbon you can use the better. Pre-preg carbons have very little resin compared to the weight of the carbon. So every 100 grams of carbon may have between 38 and 42 grams of resin to bind it. If they used a good vacuum method this would be about 100 grams of resin per 100 grams of carbon and if they went really old school and didnt use any form of pressure or vacuum then there would be up to 300 grams of resin per 100 grams of carbon. Pre-preg carbons are also cooked at a higher temperature to both speed up the curing process and add some strength too. Polyester cannot usually take over 65 degrees C and would need 8 hours or more to cure enough to be taken out of a mould. Pre-pregs can be cooked at 120 degrees C or more and can be taken out of the mould in less than an hour. The only good thing about polyester resins are they are UV stable and great for cheaper cosmetic parts. Structural parts need to be done in a pre-preg epoxy carbon.

stubs

Daz555 wrote:

http://www.youtube.com/watch?v=6APhKvaW6ig

Pretty damn impressive :shock:

I want to work there and break stuff.

mike hunts alpine

stubs wrote:

I read an article in one of the bike mags about carbon frames. Apparently Steel and Alu frames have finite fatigue lives they will eventually fail, it might be decades but they will crack eventually. Carbon and Titanium have infinite fatigue lives and theoretically as long as they arent subject to massive stress that they arent designed for will last forever. The article also said if a carbon frame has a fault it will fail very early on, if its been okay for a year it will be okay for the life of the frame. Carbon frames do break but so does any frame material if a bike was guaranteed not to fail it would weigh as much as an anvil.

I have a carbon H/T and on its 2nd ride I dropped it and it whacked into a rock I though shoot thats the frame dented, when checked all I could see was an almost invisible surface scuff on the top coat that might have been from the strap that held the bike in the rack. A mate is keen on canoeing and he has been using carbon paddles for years and they are covered in gouges, scrapes and dings and he reckons they are as good as new. He has repaired paddles and canoes with fibre and epoxy resin and reckons if I bust my frame he could repair it for me. Hopefully I wont be taking him up on his offer.

+1

thelonegroover

morepower wrote:

Thelonegroover wrote:

From a chemical point of view, polyester degrades due to water but this doesn’t stop it being used very successfully for waterproofs and tents etc.

Bike frames are made from a pre-preg carbon which does not use a polyester resin. The resin is not suited to the process used due to the cure times so epoxy is used. Epoxy resins also "wet out" the carbon better so you have less resin and more carbon pound for pound. Resin has very little strength so the more carbon you can use the better. Pre-preg carbons have very little resin compared to the weight of the carbon. So every 100 grams of carbon may have between 38 and 42 grams of resin to bind it. If they used a good vacuum method this would be about 100 grams of resin per 100 grams of carbon and if they went really old school and didnt use any form of pressure or vacuum then there would be up to 300 grams of resin per 100 grams of carbon. Pre-preg carbons are also cooked at a higher temperature to both speed up the curing process and add some strength too. Polyester cannot usually take over 65 degrees C and would need 8 hours or more to cure enough to be taken out of a mould. Pre-pregs can be cooked at 120 degrees C or more and can be taken out of the mould in less than an hour. The only good thing about polyester resins are they are UV stable and great for cheaper cosmetic parts. Structural parts need to be done in a pre-preg epoxy carbon.

I appreciate carbon fibre bikes are not made with polyester. Just making the point that some things react differently in the real world from what you’d expect in theory. Personally I’d much rather have carbon than aluminium. In fact I’d have steel over aluminium.

morepower

Thelonegroover wrote:

I appreciate carbon fibre bikes are not made with polyester. Just making the point that some things react differently in the real world from what you’d expect in theory. Personally I’d much rather have carbon than aluminium. In fact I’d have steel over aluminium.

True. Even an epoxy resin used for pre-pregs is not the same from one supplier to another and all have different strengths and weaknesses where their properties are concerned. I make a full Monocoque seat and fuel tank which is strong and light and does everything you want apart from one thing. The fuel tank section cannot withstand ethanol well enough. So I have to buy a special epoxy resin that will withstand ethanol to seal the fuel tank, but if I make a part from it then it is flexible and has less strength than the other resin. If you use the correct resins and carbons from normal weaves to harness and unidirectional weaves and normal modulus or high modulus carbons you can make something that is not only strong but also has some flex to absorb impact as shown in the video. I would love a carbon mountain bike but sadly I will have to make do with all of the parts I have made for my motorbike... lol..

redddraggon

slickmouse wrote:

ali will last for many thousands of years if you stop it oxidizing,

Wrong.

Some Al alloys like 6061 (like most bike frame alloys) are precipitation hardening alloys, which means they age with time at a rate determined by temperature and will age even at room temperature.

Bishbosh10

stubs wrote:

I read an article in one of the bike mags about carbon frames. Apparently Steel and Alu frames have finite fatigue lives they will eventually fail, it might be decades but they will crack eventually. Carbon and Titanium have infinite fatigue lives and theoretically as long as they arent subject to massive stress that they arent designed for will last forever.

What mag was that? The Beano? :shock:

Nothing (in terms of bike frame material at least) has an infinite fatigue life, some materials will be better than others and some details (i.e. how one tube joins to another) will be better than others but they will all crack eventually. When this happens is not realistically predictable in normal usage as the number of cycles and magnitude of stress range will vary significantly. What the manufacturers do is a simulated fatigue life test that will cycle the component through a range of stresses quite a few times (were talking thousands or tens of thousands of cycles here) until they reach a number they are happy with.

At the end of the day, manufacturers spend a lot of time and money designing and testing components so we don't need to worry about things like fatigue - we just need to go out and ride it.

I would be more interested in how a frame made from a certain material felt in use and that is as much a function of design as it is material choice.

stubs

Bishbosh10 wrote:

What mag was that?

I cant remember most likely MBUK or WMTB, though possibly MBR, Singletrack or Dirt I dont particulary buy any bike mag just whatever grabs my eye on WH Smiths shelf.

rockmonkeysc

stubs wrote:

Bishbosh10 wrote:

What mag was that?

I cant remember most likely MBUK or WMTB, though possibly MBR, Singletrack or Dirt I dont particulary buy any bike mag just whatever grabs my eye on WH Smiths shelf.

All well known sources of material science information.

spankwilder

Of all the materials on my bike - I fatigue the most, my frame always looks fine.

stubs

RockmonkeySC wrote:

stubs wrote:

Bishbosh10 wrote:

What mag was that?

I cant remember most likely MBUK or WMTB, though possibly MBR, Singletrack or Dirt I dont particulary buy any bike mag just whatever grabs my eye on WH Smiths shelf.

All well known sources of material science information.

What Mountain Bike september 2013 issue no 152. If you know better than people like Peter Denk you must be an all time expert. Ex= someone who used to be good, spurt = a little drip

blinddrew

spankwilder wrote:

Of all the materials on my bike - I fatigue the most, my frame always looks fine.

^^^ This.

Bishbosh10

stubs wrote:

What Mountain Bike september 2013 issue no 152. If you know better than people like Peter Denk you must be an all time expert. Ex= someone who used to be good, spurt = a little drip

Really? That's what you're bringing to a technical discussion?

No idea who Mr Denk is, nor do I care. I was challenging what you wrote, which was simply incorrect. No need for toys to be thrown just acknowledge it was incorrect or put forward your argument as to why you believe you think you are correct and we go on from there. That is how a discussion works.

stubs

Bishbosh10 wrote:

stubs wrote:

What Mountain Bike september 2013 issue no 152. If you know better than people like Peter Denk you must be an all time expert. Ex= someone who used to be good, spurt = a little drip

Really? That's what you're bringing to a technical discussion?

No idea who Mr Denk is, nor do I care. I was challenging what you wrote, which was simply incorrect. No need for toys to be thrown just acknowledge it was incorrect or put forward your argument as to why you believe you think you are correct and we go on from there. That is how a discussion works.

I am not bringing anything to the discussion apart from the fact that people who actually work with carbonfibre rather than bullshit about it might know what they are talking about. If you google Peter Denk you might learn something.

Richie63

In practical terms you would be more than likely to get a newer model/sell the bike/ stop cycling before the frame started to fail.

Hopefully you would never find out

stubs

failures in my opinion are a lot less common than they used to be. In the 90s Cannondale were known as Crackanfail. Around the same time I had a Specialized steel frame that failed when a weld just parted like wet paper, when I took it back to the shop the owner had a shed full of broken frames that were waiting for repair or replacement. I doubt a bike shop sees many failed frames these days.

Bishbosh10

stubs wrote:

failures in my opinion are a lot less common than they used to be. In the 90s Cannondale were known as Crackanfail. Around the same time I had a Specialized steel frame that failed when a weld just parted like wet paper, when I took it back to the shop the owner had a shed full of broken frames that were waiting for repair or replacement. I doubt a bike shop sees many failed frames these days.

I would agree with that statement - the advances in computer analysis packages in the last 20 years combined with the improved computing performance means that more refined models can be built and run resulting in the wafer thin but strong where they need to be frames of today.

The failure of a weld could be down to a myriad of reasons. If I was a betting man I would put my money on the weld being poorly executed resulting in poor penetration, but it could be a defect in the weld causing a stress concentration that precipitated a crack. Could also be fatigue but the detail would have to be terrible for that to be the root cause I would suggest.