CARBON - Frames - How long...

[kyuss]

The failure mode of different materials is irrelevant to the original question, how long does it last? A crashed steel frame that's been bent in half is just as useless as a broken carbon one and it hasn't lasted any longer has it?

IMO if you don't crash the thing in the first place, it'll last just as long if not longer than any steel or aluminium bike. They don't rust like steel and don't become weaker over time like aluminium.

 

[yenrod]

That's probably why titanium is becoming so popular now and so many companies are now specialising in this material.

How about an Enigma ?

Titanium did used to be popular..then Carbon got a BIG look-in which is continuing...

Ive heard Titanium is quite flexible ?

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Ever had a strand of Carbon in your hand: its pretty dam tough - irritatingly tough TBH/actually...add in the glue or however its made/put together and you've a massively strong material !

Saying that and taking in ALL the above: I feel its a great material BUT there are areas whereby it shoudn't be made for use IE forks, handlebars.

 

[Steve Austin]

so tell me what will happn if you take a steel tube and one made from carbon fibre and start to bend it?

Will the CF bend like the steel or will it snap?

of tkae the same two tube and whck them really hard with a hammer?

will the CF faltten like the steel tube or will ir break?

1. Like fishing rods. some of them are carbon. built to be light strong and whippy. Very unlike bike frames.

2 CF can be built to do lots of things

3. Most tubular structures on bikes would bend/crush/squash under force from,a hammer. steel will dent,bend etc. Carbon will shatter/splinter

ALL totally irrelevant to bike frames btw

 

[Blue]

of tkae the same two tube and whck them really hard with a hammer?

will the CF faltten like the steel tube or will ir break?

I'll let you know the next time I whack my beloved CF with a hammer

Seriously, the nearest I've seen to this was a downhiller who lost it and just fell heavily onto his top-tube with quite a thump. The frame didn't crack and fall apart, it delaminated, but stayed in one piece. The frame was a write-off, but I don't think it was because of the material!

 

[02GF74]

The failure mode of different materials is irrelevant to the original question, how long does it last? .

correct but I was repsonding to this:

I don't think it's a more risky material than steel or aluminum etc, just that the way it behaves and wears out is different.

and back to the orignal question as for how long they last?

which do you think will last longer
1. a steel frame left in the sun or a CF fibre frame?

Would the UV in the sun not attack the resin over time?

my money is on the steel frame unless some says otherwise.

 

[kyuss]

and back to the orignal question as for how long they last?

which do you think will last longer
1. a steel frame left in the sun or a CF fibre frame?

Would the UV in the sun not attack the resin over time?

my money is on the steel frame unless some says otherwise.

The laquer used on carbon frames protects against any major UV damage. It's like suntan lotion for bikes. I think you'd have to leave it out in pretty strong sunlight for an awful long time (probably many years) before it was unsafe to ride.

You could equally ask a similar question. Which do you think would last longer? A steel frame left out in the rain or a carbon one? My money is on carbon.

Neither of these questions really relate to real world usage of a bike though.

 

[02GF74]

Neither of these questions really relate to real world usage of a bike though.

once again you are right since we don't ride out bikes when it is sunny let alon rainy.

this makes interesteing reading, althoug it discuses CF masts it - rain can affect carbon fibre too.

Epoxy resins are UV light degraded. Excessive UV light has the effect of
turning the exposed epoxy resin into a chalky layer, which can then easily fall
off resulting in exposure of the fibres to the weather. Moisture can then enter
the exposed fibres and cause wicking to the inside of the laminate, which
further reduces the laminate’s strength and integrity.​

and

Carbon fibre composites do not yield (plastically deform) prior to failure.
Often little warning is given that the tube is likely to fail.

<--- whcih is what I said oin the first post.

linky​

 

[02GF74]

3. Most tubular structures on bikes would bend/crush/squash under force from,a hammer. steel will dent,bend etc. Carbon will shatter/splinter

ALL totally irrelevant to bike frames btw

why?

you go over a huge bump; steel frame will bend, CF will shatter. the former may mean you are still in control, the latter you are rolling around on the ground saying "argghh, call an ambulance".

or you smash into a tree, car, wall etc.

formet means forks are bent but you are still in control, latter you are on the ground as before.

 

[kyuss]

once again you are right since we don't ride out bikes when it is sunny let alon rainy.

Of course we do, but there's a big difference to riding your bike every day for a couple of hours and leaving it out in the sun/rain for years on end.

this makes interesteing reading, althoug it discuses CF masts it - rain can affect carbon fibre too.

Epoxy resins are UV light degraded. Excessive UV light has the effect of turning the exposed epoxy resin into a chalky layer, which can then easily fall off resulting in exposure of the fibres to the weather. Moisture can then enter the exposed fibres and cause wicking to the inside of the laminate, which further reduces the laminate’s strength and integrity.

From the very next paragraph in the document you linked to:

Whilst these two effects can be either avoided or are relatively long term (many dinghy sailors have chosen to leave their masts naturally black) we recommend painting the composite tubing with a UV resistant polyurethane based paint or clear coating. Correct application of paint will effectively eliminate degradation due to these effects and allow the other long life properties (i.e. excellent corrosion and fatigue resistance) of composite tubing to be realised.

 

[Chris James]

The failure mode of different materials is irrelevant to the original question, how long does it last?

You are quite correct. Although I would say that when people ask how long a frame lasts they really mean how long will I feel safe using the frame? Most of use would prefer to retire a frame rather than know it has reached the end of its life when you face plant tarmac at 25 mph.

Since carbon fibre cannot be visually inspected then this may well lead one to change a frame before it has worn out, to be on the safe side. So the practical life of a carbon fibre frame may well be shorter than the theoretical life.

As far as crashes are concerned. Whjat constitutes a crash? I have come off on black ice on a steel framed bike and have absoloute confidence that the frame was not damaged and that its life not reduced in any way.

If the same had happened on a carbon fibre bike I may feel less happy on 40mph+ descents.

The concern about CF is not in crashes where the frame is smashed to bits but ones where it looks fine after the crash but the damage has occurred internally and will lead to early failure at some point donw the road.

So I do think that failure modes are important when considering how long you might want to use a bike for. Of course frames of all materials can be made massively strong and will last pretty mcuh forever. But we know that frames are always a trade off between weight, stiffness and longevity.

 

[Blue]

CF has been around for a few years.

Unless the scaremongers can produce the examples of frames disintegrating while being ridden I would suggest the theories be stuffed where the sun don't shine.

I don't understand how people with zero evidence can expound their ill-founded opinions in such a forthright manner.

 

[Mr Pig]

Unless the scaremongers can produce the examples of frames disintegrating while being ridden I would suggest the theories be stuffed where the sun don't shine.

http://materials.open.ac.uk/mem/mem_comp1.htm

 

[Steve Austin]

I bet i can find more Ally and steel frame failures. The OP was about Longevity, not Crash damage.

This is steel after some time

I don't think you'll see any Carbon Corroding

 

[Mr Pig]

Point is thought that despite obvious corrosion the steel frame hasn't actually failed yet.

 

[Steve Austin]

Can you not see the hefty great crack across the weld?