Carbon fiber bike life span
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Of course they keep changing the rules based on who's country won the previous year.
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I saw many opinions saying that a road carbon fiber bike should be changed after 6,7,10 years, to avoid risk of carbon failure. However, talking about the large pool of riders of carbon bikes from reputable brands, outside of professionals or hard racing world, I wonder:
How many road riders from above category experienced carbon fiber failure from normal riding (no hard crash or misuse), and how long (years or km) did it take for such failure to occur?
How many road riders from above category experienced carbon fiber failure from normal riding (no hard crash or misuse), and how long (years or km) did it take for such failure to occur?
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Because they presume it's a bit like plastic maybe? To be fair I've seen plenty of carbon failures from inappropriate loading (usually from clamping to bike racks). The typical pencil thin seat stays you often see on modern road bikes are also easily prone to damage from everyday knocks. I'm always very careful when leaning my bikes up not to catch those on sharp edges of walls etc.
Good idea.
But... I wanted to "count" the failures during normal use, and the km or time period until the failure occurred. That might give a more practical perspective over the lifespan of a carbon bike for common users - as opposite to many articles that mix normal usage, poor construction, crashes, misuses and abuses - etc, to come up with a general and useless conclusion that, yes, carbon bikes fails, so you should replace your bike with a new one from time to time, for safety reasons...
But... I wanted to "count" the failures during normal use, and the km or time period until the failure occurred. That might give a more practical perspective over the lifespan of a carbon bike for common users - as opposite to many articles that mix normal usage, poor construction, crashes, misuses and abuses - etc, to come up with a general and useless conclusion that, yes, carbon bikes fails, so you should replace your bike with a new one from time to time, for safety reasons...
Similar to what we've heard a lot in public statements and speeches "many people are saying..."
Last edited by Camilo; 11-09-22 at 12:48 AM.
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It's illusory to talk about bike life span in terms of years. Bike frame fatigue which happens inevitably with all materials is a product of mileage, riding style, rider weight and power (out of the saddle grinding subjects the frame to much higher forces than climbing in the saddle, even higher than hitting road bumps), amount and severity of manufacturing defects (which happen, even in metals; just ask all the people who had a Ti frame break at the welds) and any impacts which may have created dents / cracks / delaminations / etc which may have weakened the material.
You can go down the rabbit hole of examining articles about bike and fork fatigue testing and so on, but it's really hard to translate how many cycles of what force to miles on the road, especially as there's a huge difference in terms of forces between eating up miles spinning on the flat on a smooth road, and a ride in the mountains over crap roads.
You can go down the rabbit hole of examining articles about bike and fork fatigue testing and so on, but it's really hard to translate how many cycles of what force to miles on the road, especially as there's a huge difference in terms of forces between eating up miles spinning on the flat on a smooth road, and a ride in the mountains over crap roads.
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It's illusory to talk about bike life span in terms of years. Bike frame fatigue which happens inevitably with all materials is a product of mileage, riding style, rider weight and power (out of the saddle grinding subjects the frame to much higher forces than climbing in the saddle, even higher than hitting road bumps), amount and severity of manufacturing defects (which happen, even in metals; just ask all the people who had a Ti frame break at the welds) and any impacts which may have created dents / cracks / delaminations / etc which may have weakened the material.
You can go down the rabbit hole of examining articles about bike and fork fatigue testing and so on, but it's really hard to translate how many cycles of what force to miles on the road, especially as there's a huge difference in terms of forces between eating up miles spinning on the flat on a smooth road, and a ride in the mountains over crap roads.
You can go down the rabbit hole of examining articles about bike and fork fatigue testing and so on, but it's really hard to translate how many cycles of what force to miles on the road, especially as there's a huge difference in terms of forces between eating up miles spinning on the flat on a smooth road, and a ride in the mountains over crap roads.
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*Modulus Graphite, the company that invented the use of carbon fiber for guitar and bass necks, refers to that particular random pattern, the one that looks like "burnt MDF plywood" [sic] as KLD...an acronym for One Thousand Ladies Dancing.
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No, what you're seeing in either picture is simply two alternatives for the cosmetic layer, the first one a weave and the second one a random pattern*. The actual structural carbon in both examples is underneath the cosmetic layer, and is almost certainly unidirectional fiber...which looks like neither. Unidirectional fiber typically looks pretty benign/boring; sometimes you can determine the direction of the fibers, but if they are fine enough it just looks like matte gray plastic.
*Modulus Graphite, the company that invented the use of carbon fiber for guitar and bass necks, refers to that particular random pattern, the one that looks like "burnt MDF plywood" [sic] as KLD...an acronym for One Thousand Ladies Dancing.
*Modulus Graphite, the company that invented the use of carbon fiber for guitar and bass necks, refers to that particular random pattern, the one that looks like "burnt MDF plywood" [sic] as KLD...an acronym for One Thousand Ladies Dancing.
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A properly designed and constructed carbon bicycle frame has a virtually infinite fatigue life. Under normal (not involving a crash that exceeds the limits of the frame construction) conditions a carbon frame will outlast the rider pretty easily.
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But "classic bi-directional weave" is (was) almost always used as a cosmetic layer only, because there are very few locations on a bicycle frame -- especially where two or more tubes join one another -- where you want structural fibers oriented uniformly at a perfect 90° angle to one another.
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I don't believe that is true, but I'm not by any means a composites expert. There are properties of both unidirectional and woven bi-directional carbon that are beneficial to the combined structure. There may well be more emphasis on unidirectional layers in a high-end modern bike frame, but woven carbon is not merely for cosmetic use.
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The only thing people really need to know to come to the answer is there are millions of carbon bikes being ridden every day, some of them have seen decades of service. Carbon fiber isn't inherently unsuitable for bikes, no matter what scary things the internet says.
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Rode on my 20-year old cf fork again today. Did not die.
Will report back the next time I ride it.
Will report back the next time I ride it.
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For our sake and the sake of your loved ones, you should install an app on your phone which will post here as well as text loved ones if your movement and heart both stop, with accelerometer data.
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Well, I did have one of the Specialized helmets with the ANGI system -- it was supposed to alert my wife if I crashed and was unconscious. But I figured she would just start working on her eHarmony profile rather than call an ambulance, so I turned it off.
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I saw many opinions saying that a road carbon fiber bike should be changed after 6,7,10 years, to avoid risk of carbon failure. However, talking about the large pool of riders of carbon bikes from reputable brands, outside of professionals or hard racing world, I wonder:
How many road riders from above category experienced carbon fiber failure from normal riding (no hard crash or misuse), and how long (years or km) did it take for such failure to occur?
How many road riders from above category experienced carbon fiber failure from normal riding (no hard crash or misuse), and how long (years or km) did it take for such failure to occur?
As you can see here, there are plenty of riders who have ridden carbon bikes for more than 2 decades with no issues.
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Noticed. But the takeaway for the moment is that nobody (yet) claimed here retiring road carbon bike due to failing during normal use. This might be a little piece of answer to my question.
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As far as I know, carbon does not deteriorate with age or for that matter mileage. It only "ages" with abuse such as riding it off a cliff or colliding with a motor vehicle. And in either of those scenarios, your carbon fiber frame will be the least of your worries.
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I don't believe that is true, but I'm not by any means a composites expert. There are properties of both unidirectional and woven bi-directional carbon that are beneficial to the combined structure. There may well be more emphasis on unidirectional layers in a high-end modern bike frame, but woven carbon is not merely for cosmetic use.
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I mean, seriously, folks, a cyclist climbing out of the saddle is a much more torquey machine than a typical motorcycle and the forces have a sideways and twisting component and are more choppy then a typical engine. Just climbing out of the saddle at a moderate 350W and 50 rpm is 66Nm of torque. How heavy is a motorcycle frame? A composite bike frame is 800 to 1100 grams, a quality metal one is 1500 to 1800 grams, of course they're all going to die to fatigue with enough miles.
Yesterday we were climbing a mountain and at the foot of the climb one of the riders had his old CF frame die, crack at the chainstay. It happens.
Last edited by Branko D; 11-13-22 at 10:25 AM.
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You could literally google composite fatigue and find out that it's wrong in two minutes - it deteriorates with (sometimes) age and particularly mileage.
I mean, seriously, folks, a cyclist climbing out of the saddle is a much more torquey machine than a typical motorcycle and the forces have a sideways and twisting component and are more choppy then a typical engine. Just climbing out of the saddle at a leisurely 350W and 50 rpm is 66Nm of torque. How heavy is a motorcycle frame? A composite bike frame is 800, 900 grams, a metal one is 1500-1800 grams, of course they're all going to die to fatigue with enough miles.
Yesterday we were climbing a mountain and at the foot of the climb one of the riders had his old CF frame die, crack at the chainstay. It happens.
I mean, seriously, folks, a cyclist climbing out of the saddle is a much more torquey machine than a typical motorcycle and the forces have a sideways and twisting component and are more choppy then a typical engine. Just climbing out of the saddle at a leisurely 350W and 50 rpm is 66Nm of torque. How heavy is a motorcycle frame? A composite bike frame is 800, 900 grams, a metal one is 1500-1800 grams, of course they're all going to die to fatigue with enough miles.
Yesterday we were climbing a mountain and at the foot of the climb one of the riders had his old CF frame die, crack at the chainstay. It happens.
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86 Nm at a 25% climb
Metal frames are operating under the fatigue limit at all times? CF frames never fatigue? Why do they eventually crack, then?
It’s a bold claim which doesn't seem to be supported by any literature which examines bicycle frame fatigue.
Last edited by Branko D; 11-13-22 at 11:55 AM.