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PostPosted: Fri Aug 22, 2014 2:58 pm 
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Location: Urbana, Illinois
I know there will be a few here that won't ride carbon bars at all. I'm not one of those. I do trust carbon but also recognize everything has a limit to its life.

I have a set of Zipp SL carbon bars that I purchased in 2006 and are still on my main road bike today. They have easily over 30,000 miles on them and have see a few crashes that just resulted in some loss of clear coat on the ends. I inspect them regularly and no signs of cracks in the carbon or clear coat. I've always religiously used a torque wrench for the mount and the shifters.

I'm considering replacing them since I can get a set of the same bars, (NOS), since I really like the shape, reach and drop on these bars. I think I've got my moneys worth out of them.

How long would you ride your bars or how long have you ridden your bars?

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PostPosted: Fri Aug 22, 2014 3:23 pm 
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Forever as long as they appear to be safe [no cracks, crashes, etc]. I'm no engineer, but I would think the fatigue life is a very long time. Much longer than the hours I spend on the bike.

Of course, my bars are kinda hefty.


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PostPosted: Fri Aug 22, 2014 3:33 pm 
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Location: Australia
I'd never thought of carbon bars as having a shelf life. In the same vein, how long do I have on my carbon frame that's done nearly 50,000kms before I have to throw it in the bin?


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PostPosted: Fri Aug 22, 2014 3:36 pm 
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Posts: 62
It would depend if you have a history of stuff breaking. Some people, for whatever reason, have stuff break on them. I know people who can't go a season without some broken spoke, snapped chain or other nonsense that never happens to me. I've probably jinxed it now but for me personally I wouldn't ever stop using my carbon bars unless their integrity was in question. One of the easy ways to test is take the bar completely off (off the stem, remove shifters) and pull the bar tape. Tap the bar with a coin and listen. The sound should be pretty sharp and consistent. If it sound is more like a thud in places then you have structural issues.

Even then, I might consider moving the bars to a bike I ride solely on the trainer.


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PostPosted: Fri Aug 22, 2014 4:56 pm 
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If they still work, aren't broken or risk of failure, why would you not keep using them? I would keep using it. I don't think they have an expiration date after 30,000 miles.

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PostPosted: Fri Aug 22, 2014 5:07 pm 
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I recently cut 5,5 cm of my BMC TCC seatpost, trying to save some weight. Ended up saving 16 grams :lol:
The 5,5 cm left over part was useless and I thought I would test how strong it was before throwing it in the trash. So, just for fun and maybe to get rid of some work related stress, I started banging it with a hammer. :twisted:
I started tapping it gently, then hitting it harder and harder. After a couple of hits I was hitting it as hard as I could, from different angles. Except for some light scuff marks in the clear coat, nothing happened. And believe me, I was hitting it as hard as I could. So I took another hammer, with a more pointy end and hit it several times as hard as I could. Only then the coating started to chip. I thought it would have shattered on the first gently hit... But the carbon is still intact.

I have an Easton CT2 carbon mtb bar (think I bought it somewhere in 2001) that was (ab)used for several years in both marathon and xc competition. Except for some minor chipping of the carbon on the outer ends from numerous crashes, it is still going strong. I recently took a hacksaw and cut 0,5cm from each end, so the outer ends are now clean and no longer chipped. It's back on the winterbike now and will probably survive many more years...

I'm not sure about crazy uberlight carbon parts though, but I wouldn't buy those anyway due to budgetary constraints :(


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PostPosted: Fri Aug 22, 2014 5:14 pm 
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Now that I'm thinking about it, I may clamp it into a vice and just keep increasing the clamping force. That should make it go snappedy snap :twisted: Now where did I put my safety goggles? :mrgreen:


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PostPosted: Fri Aug 22, 2014 6:04 pm 
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Don't laugh about saving 16 grams. That's half the total weight saved in switching from the Trek Madone to the Emonda, using claimed weight numbers for vapor coat.

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PostPosted: Sat Aug 23, 2014 1:43 am 
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If the bars were to fail I don't think they would all of a sudden just snap under your load, I presume you would feel some flex first. Unless of course they ae broken due to a crash

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PostPosted: Sat Aug 23, 2014 3:41 am 
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Location: Perth, Western Australia
Carbon does not generally have a fatigue life, unless damaged.
These days most commercial airliners have extensive use of carbon fibre in their construction, and many aircraft have a service life of 10-20 years.

@djconnel - I'm with you on this. As a Madone owner I can't quite figure the motivation for the Emonda.


Parlee Z5, Trek Madone, Colnago Dream,

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PostPosted: Sat Aug 23, 2014 8:00 am 
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Oswald wrote:
Now that I'm thinking about it, I may clamp it into a vice and just keep increasing the clamping force. That should make it go snappedy snap :twisted: Now where did I put my safety goggles? :mrgreen:


I did that once with a piece of cut off Enve fork steerer tube. I gave up after a while, seeming to do next to no damage to the tube. My confidence in CF tubing was quite a bit higher after that exercise.


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PostPosted: Sat Aug 23, 2014 3:24 pm 
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I would never worry about a set of bars unless they had been crashed, hard. That being said I was racing behind a guy who's bike all of a sudden leapt into the air in front of me as we were winding up for the final sprint on the home straight. His bars had snapped off flush with his stem on one side and gone into his front wheel, stalling his bike. He thankfully was on a lean to the right when it snapped, putting himself into the infield, he landed on grass and was uninjured. Obviously this was due to too much stem faceplate tension and subsequent stress. Carbon is very strong, but the torque ratings are there for a reason.

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PostPosted: Sun Aug 24, 2014 2:28 pm 
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Location: Natovi Landing
Ozrider wrote:
Carbon does not generally have a fatigue life, unless damaged.
These days most commercial airliners have extensive use of carbon fibre in their construction, and many aircraft have a service life of 10-20 years.

@djconnel - I'm with you on this. As a Madone owner I can't quite figure the motivation for the Emonda.


Parlee Z5, Trek Madone, Colnago Dream,


Commercial airliners have a service life far longer than that generally - though parts of them are replaced after a certain amount of hours ... don't know re carbon fibre parts on newer aircraft and would be interested if anyone does. Most large commercial aircraft will see at least 25 and often 35 years service.

To the OP ... I rode a set on one bike from 06-12 when I snapped them in a crash. No issues through
50,000 km+ Keep riding them!

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PostPosted: Sun Aug 24, 2014 3:23 pm 
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Posts: 556
Fatigue is not a function of miles. it is a function of loading cycles at a certain stress. For example see here.

http://en.wikipedia.org/wiki/Fatigue_limit

i.e. if you load your bars at 1000N as compared to someone who loads them at 500N ( AND it depends on the type and direction of load), obviously the one with 1000N will fail faster.

Anyway, what you want to look for are cracks that grow. Classical material failure theory is based on crack propogation. Cracks are alright so long as they reach a critical size- until which after catastrophic failure occurs. here you can see a picture of how cracks grow until the structure has insufficient strength to bear the load. http://www.lambdatechs.com/failure-analysis.html
Airbus 380s fly with cracks in their superstructure- so long as these cracks do not reach critical size ( there is probably a factor of safety built in) the airbus is still flying without service.

I wouldn't be too worried about your bars failing. engineering parts are usually built with a factor of safety built in unless you install them wrongly or somethign bad happens.
the key here is constant inspection and maintenance of your bike. when you do this you will notice any cracks that happen. I'd say your bars are good. inspect every few months or so. if you notice any cracks that start to grow, replace. I ride with a small crack in my seatpost which I keep track of the size of with a gold marker.

If you're REALLY afraid, find a friend with an X ray machine. lots of doctors private clinics have this so i you've got a doctor friend whom you can call in a favour after hours you could X ray your bars. wouldnt cost much and you'd be 100 % sure if there are any cracks worth worrying over.


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PostPosted: Sun Aug 24, 2014 3:25 pm 
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Joined: Fri Feb 10, 2012 4:27 pm
Posts: 556
Fatigue is not a function of miles. it is a function of loading cycles at a certain stress. For example see here.

http://en.wikipedia.org/wiki/Fatigue_limit

i.e. if you load your bars at 1000N as compared to someone who loads them at 500N ( AND it depends on the type and direction of load), obviously the one with 1000N will fail faster.

Anyway, what you want to look for are cracks that grow. Classical material failure theory is based on crack propogation. Cracks are alright so long as they reach a critical size- until which after catastrophic failure occurs. here you can see a picture of how cracks grow until the structure has insufficient strength to bear the load. http://www.lambdatechs.com/failure-analysis.html
Airbus 380s fly with cracks in their superstructure- so long as these cracks do not reach critical size ( there is probably a factor of safety built in) the airbus is still flying without service.

I wouldn't be too worried about your bars failing. engineering parts are usually built with a factor of safety built in unless you install them wrongly or somethign bad happens.
the key here is constant inspection and maintenance of your bike. when you do this you will notice any cracks that happen. I'd say your bars are good. inspect every few months or so. if you notice any cracks that start to grow, replace. I ride with a small crack in my seatpost which I keep track of the size of with a gold marker.

If you're REALLY afraid, find a friend with an X ray machine. lots of doctors private clinics have this so i you've got a doctor friend whom you can call in a favour after hours you could X ray your bars. wouldnt cost much and you'd be 100 % sure if there are any cracks worth worrying over.


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