# How long or how many miles do carbon forks last?



## JFRCross (May 25, 2007)

I have a 10 year old Ibis Titanium road frame with a Kestrel EMS Pro fork. I know the frame will last for a long time if not forever, but I would think that the fork is fatiguing and will break down at some point. How many miles is a fork good for before replacing it? The frame still rides as great as ever and the fork feels fine, but I do not want to be on it if it is likely to fail due to fatigue at some point.

Thanks in advance for your thoughts


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## Ventruck (Mar 9, 2009)

Replacement is due once you actually notice signs of fatigue. No one non-jokingly knows the degradation of carbon fiber over time, and wear is completely dependent on the way it was ridden.

If you find yourself really insecure about it, just get a non-carbon fiber replacement fork.


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## JFRCross (May 25, 2007)

Thanks. I am not insecure and it really rides fine and still corners great. Just curious and if it should be replaced after a certain amount of miles, I will. When and if I do replace it, it will be with another carbon fork though.


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## SilverStar (Jan 21, 2008)

Carbon doesn't "go bad" over time...Ventruck has good advice: replace when it is needed or if you want some extra peace of mind.


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## Dajianshan (Jul 15, 2007)

It is time to replace a carbon fork as soon as it fails.


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## dhfreak (Sep 12, 2009)

Dajianshan said:


> It is time to replace a carbon fork as soon as it fails.



YES ... LOL. If the fork is riding fine I would imagine it is still doing okay. Is there not what you really need to worry about is the fatigue life of your valve stems!!

Mike


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## Gill-Again (Mar 11, 2004)

Just don't get them wet. They will assplode!


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## Blue CheeseHead (Jul 14, 2008)

Gill-Again said:


> Just don't get them wet. They will assplode!


No, it's not water, it's sunlight. That's why I only ride at night.


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## JFRCross (May 25, 2007)

Thanks, I think we are done here.


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## tom_h (May 6, 2008)

Strictly speaking, carbon fiber parts won't fatigue. I've read of LOOK testing their CF forks for millions of harsh bending cycles (ie, 1/4 inch or more) and they're fine.

I would also trust all-carbon forks more than CF bonded to aluminum steerer tubes -- the bond could be a weak point.

If you crashed, or hit a really deep pothole at high speed, take the fork off and inspect ... otherwise, enjoy. CF forks are pretty much standard now on any decent road bike, obviously excepting the Walmart-level crap bikes


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## dookie (Oct 1, 2007)

until you crash it.


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## Kerry Irons (Feb 25, 2002)

*Sting theory*



JFRCross said:


> I have a 10 year old Ibis Titanium road frame with a Kestrel EMS Pro fork. I know the frame will last for a long time if not forever, but I would think that the fork is fatiguing and will break down at some point. How many miles is a fork good for before replacing it? The frame still rides as great as ever and the fork feels fine, but I do not want to be on it if it is likely to fail due to fatigue at some point.


You should re-phrase your question to "How long is a piece of string?" 

My current CF fork has 110,000 miles on it. I weigh 180 lbs. It shows no sign of deterioration, but it could break at any time. So there.


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## sanrensho (Jan 2, 2003)

Another factor to consider is that the Kestrel EMS forks are solidly built. My EMS fork weighed close to 500 grams and I believe your EMS Pro weighs about the same. They were not ultra-light, weight weenie forks.

I replaced my EMS fork only because I wanted to shave weight, otherwise I would still be riding it.


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## km53jinx (Apr 9, 2002)

It probably depends on how hard you are on your equipment overall. If you are a more aggressive rider, you likely will need to replace parts more often. If you cannot feel or see damaged areas yourself, you should have a reputable racing shop thoroughly check your ride on a regular basis and replace any parts as needed. Common sense will need to take over here.


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## FlatlandRoller (Jan 22, 2004)

The fork is probably stronger than your frame, I don't think I'd worry.


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## Maximus_XXIV (Nov 10, 2008)

Carbon does not fatigue, end of story.

Watch for cracks and bulges for signs you exceeded the elasticity of the carbon.

It does fall apart if you look at it funny. Steel goes soft with age and aluminum is harsh. Ti is real and shiny.


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## Kerry Irons (Feb 25, 2002)

*Bad data*



Maximus_XXIV said:


> Carbon does not fatigue, end of story.
> 
> Watch for cracks and bulges for signs you exceeded the elasticity of the carbon.
> 
> It does fall apart if you look at it funny. Steel goes soft with age and aluminum is harsh. Ti is real and shiny.


Gee, a real stew of misinformation. 

CF composite faile due to matrix failure, fiber failure, and fiber pullout. While this is not fatigue in the metalurgy sense, the effect is very similar in practice. It's not just about the fibers, but about the entire composite.

Steel does NOT go soft with age unless it is flexed beyond its fatigue limit, in which case it will remain bent. Aluminum frames are harsh ONLY if they are designed that way.


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