Life expectancy of carbon fiber

[fogrider]

I was riding with a guy that was telling me that his carbon frame was getting soft. This was surprising to me, I don't this is the case. Thoughts?

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[weisan]

http://www.reactiongifs.com/wp-content/uploads/2013/03/oh-boy.gif

:p

his carbon frame was getting soft

Tell your friend to do a thorough pre-flight inspection. The frame is trying tell him something.

[sandyrs]

Someone with an engineering background can correct me if I'm wrong, but this sounds like total nonsense; I would think that if carbon were going to fail, it would crack and fail noticeably, not "get soft." The whole "getting soft" thing has always seemed to be something that exists purely in riders' heads, completely unsupported by any actual evidence.

[Mark McM]

Unless the carbon fiber is delaminating or the fibers are breaking (and therefore the frame is on the verge of total failure), the frame will not get soft.

Likewise for metal frames, unless there are fatigue cracks propagating through the metal (and the therefore the frame is on the verge of total failure), the frame will not get soft.

Don't buy any bridges from this guy.

[Kontact]

I think the soft thing has been largely disproved. If a CF frame where to change character over time it would require a high number of micro-fractures spread out evenly in critical areas to allow more flex without actual cracking (like old rattan), and it doesn't appear that actually ever happens.

[Catdr]

Perhaps he is looking for an excuse to buy a new frame.

[nate2351]

My theory is most people aren't checking their spoke tension...

[rnhood]

I think the soft thing has been largely disproved. If a CF frame where to change character over time it would require a high number of micro-fractures spread out evenly in critical areas to allow more flex without actual cracking (like old rattan), and it doesn't appear that actually ever happens.

Pretty much true. Some of the 'softening' idea probably comes from fiberglass construction, where over time the small strands break and pull loose thus softening the composite structure.

[SoCalSteve]

I was riding with a guy that was telling me that his carbon frame was getting soft. This was surprising to me, I don't this is the case. Thoughts?

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Have him pump his tires...:confused:

[batman1425]

Just keep it out of the sun so it doesn't melt and it should be fine.

[fogrider]

Have him pump his tires...:confused:This is the guy thats telling me that lower tire pressure is faster! Its like talking to flat earthers!

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[54ny77]

maybe he was referring to his gut.

:D

[topflightpro]

It was likely soft from the get go.

A lot of frames are very thin in areas they do not need much structural rigidity. For example, the top of the top tube on many bikes is soft. You can feel it give a bit if you push your thumb into it. Same with the side walls of many carbon wheels, where the carbon provides an aero fairing and not much more..

But really, I'm pretty sure the airplanes, cars, boats... being constructed out of carbon fiber are expected to last decades.

[FlashUNC]

It'll last til the heat death of the universe.

[MattTuck]

This is what the CEOs of Specialized, Trek, Cannondale, Giant and every other bike manufacturer are doing when they hear someone believe this nonsense.

https://media0.giphy.com/media/DyTreqKSAqjLy/giphy.gif

What's better than planned obsolescence? Making the customers believe it, without actually planning it.

[Mark McM]

This is the guy thats telling me that lower tire pressure is faster! Its like talking to flat earthers!

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Sometimes lower pressure is faster:

https://cdn.shopify.com/s/files/1/0309/9521/files/Theoretical_and_Real_Roller_Plus_Tom_A_Asphalt_gra nde.png?1941812513883533956

https://silca.cc/blogs/journal/part-4b-rolling-resistance-and-impedance

[tylercheung]

this is the main hit google keeps giving me:

https://cyclingtips.com/2015/08/what-is-the-lifespan-of-a-carbon-frame/

I think the Luescher Technik videos said something similar

My guess is that unless it is crashed, the frame won't fatigue.

[old_fat_and_slow]

I was riding with a guy that was telling me that his carbon frame was getting soft. This was surprising to me, I don't this is the case. Thoughts?

Your friend needs to get his backside recalibrated. CF does not get more compliant with age. (The frame will not get softer with age unless there is a massive delamination or gross failure of fibers propagating through his downtube or seattube, which will ultimately result in frame failure).

[Spaghetti Legs]

Probably just his legs getting soft.

My 22 year old C40 still rides pretty nice.

[jlwdm]

Not necessarily soft, but I bet the quality of the carbon fiber used in bikes today is much better than in early carbon fiber frames.

Jeff

[cnighbor1]

Or his tires need more of that hot air
His floor pump gage is no doubt now reading wrong and his tires are soft

[notsew]

Tell that to my 40 year old fiberglass sailboat. It just plastic and fibers. It will outlive all of us.

[Kontact]

Not necessarily soft, but I bet the quality of the carbon fiber used in bikes today is much better than in early carbon fiber frames.

Jeff

Kinda. Low modulus fibers are "lower quality" in that they contain more impurities compared to high modulus fibers, and the older fibers are lower modulus. But I really wouldn't expect the fibers themselves to be much of a problem - it isn't like there is a lot going on with a whisker of graphite.

If anything has changed it is likely the epoxy formulations. But composites were pretty mature aerospace technology before anyone applied them to bikes, so some of the potential quality issues of a new technology were likely worked out by the '70s.

[oldpotatoe]

:p

Tell your friend to do a thorough pre-flight inspection. The frame is trying tell him something.

then sell it to this gent..:eek: