Road Cycling - Carbon bars breaking? Urban legend?

I recently was contemplating the purchase of some Easton Equipe OS carbon bars when a guy at an LBS started spinning a yarn about all the broken carbon bars he's seen. He claims to have seen "dozens" of cases where carbon bars failed catastrophically, causing horrendous crashes. I seem to remember similar stories about carbon seat posts, which turned out to be urban legends. Anybody else heard this?

This is news to me! I'm using an Easton EC90 (http://www.eastonbike.com/COMPONENTS/bar.road.ec90.html) bar.

:eek:

Ed

I broke a set of carbon bars, but it was while mountainbiking. I crashed out (my fault) and took them in the ribs.

Carbon bars can break... much like anything else can break. I'm certain there have been failures but it's probably not to the "sky is falling" extent that some make it out to be. That said, I've got plenty of crashes (some really nasty) on my Easton MTB bars and a few on my Easton EC90 road bars and they show no sign of distress. I do regularly check them.

i really have to wonder if that's true. as mentioned above they break like anything else. i really don't think a manufacturer would be willing to put something out on the market that 'fails catastrophically'. too much libability.

I remember MTB Magazine giving an Easton Ultralite carbon seatpost 1 star because a number of them broke too easily on test rides.

I broke a set of carbon bars, but it was while mountainbiking. I crashed out (my fault) and took them in the ribs.
Ahem! Here are the pictures of your bars dear.
(pics link to larger version)
http://toolbox.homelinux.org/archives/images/bars-thumb.jpg (http://toolbox.homelinux.org/archives/images/bars.jpg)

http://toolbox.homelinux.org/archives/images/bars2-thumb.jpg (http://toolbox.homelinux.org/archives/images/bars2.jpg)
These were installed by our old LBS (we don't shop there anymore), but I believe it was just the crash that broke them & not faulty equipment or installation.

I remember MTB Magazine giving an Easton Ultralite carbon seatpost 1 star because a number of them broke too easily on test rides.

These are the same goons who broke an EPX carbon post because they were trying to twist the seatpost about by banging the side of the nose of the saddle while they had the clamp tightened down. They even admitted to scratching the post by sliding it against a sharp unfiled edge in the seat-tube. Do stupid things and pay the consequences.

I don't know if its a legend, but my manual states the bars should be replaced every two years.

I've broken the standard Cinelli bars, so I suppose you could break carbon ones, too.

Here is what I know and have seen.

All the carbon bars I have seen broken (including the one in this post), break at the stem. Most carbon bar manufacturers recommend a specific torque for clamping the bars in the stem. If you don't have a torque wrench you 'll have to guess how much to tighten the stem. Most people err on the not so tight ( if you over torque you can crush the bar ), take the bike for ride, the bars slip, and re-adjust the bars and torque the bolts even more. The initial bar slip is what will eventually lead to the handlebar failure, this slip cuts the carbon, the retightening cuts it even more and you are on your way to experiencing a failure.

On a side note I have seen light weight aluminum bars fail for the same reason. Most carbon and ultra light aluminum bars CANNOT have clip-on bars installed. If you run clip-ons make sure the bar manufacturer approves of this. I have seen crushed bars from clip-ons.

I hope this helps.
Buddy B

I don't know if its a legend, but my manual states the bars should be replaced every two years.

Which bars do you have?

I've been riding a set of Easton EC 90 bars for three years and not a lick of trouble. As mentioned in other posts carbon will snap if it is scored. This scoring causes a weak spot and if it's at the stem this is where it will snap with constant stress.

Look at it in the way that a tubing cutter works.

Be smart when installing and never overtighten.

keep in mind carbon fibers themselves have no rigidity, only tensile strength. The rigidity comes from the epoxy and chop mat used in the manufacturing process.

Most commercial CF is epoxy / CF/ epoxy / fiberglas chop / epoxy / CF / epoxy

This layering gives it it's incredible rigidity and strength...picking a poor chop mat will also screw up the part.

I suspect these urban legends might have come from the days when carbon was being first used on bikes and a few less informed makers were using the carbon fiber cloth and epoxy only...no chop...so the components flexed back and forth more easily and eventually had stress failures. In automotive, the early CF applications also had people who tried this with less than fun results. Basically, I really think component makers should say what kind of chop is used...without proper chop, you can't ensure being rigid enough to not suffer from stress fractures in the epoxy.

He claims to have seen "dozens" of cases where carbon bars failed catastrophically, causing horrendous crashes.

If he would have said "a couple of cases" I would have believed him.

An LBS where I use to live saw broken bars, FSA cranks and forks and even showed me some just before I left. Even though anything can break as Khoun said, the problem with carbon is that it snaps suddenly without warning. That means if your applying extreme leverage pressure on the bars and suddenly it snaps you have instant loss of control. Aluminum may fail too, but it will bend before snapping giving you some warning. You would think that if a manufacture is telling you to replace the bar or whatever every 2 years then they know something we don't know, and they don't want to be held liable for what they know. Are you reading between the lines here?

i have some 3t big man bars

it would be hard to break them


although i did destroy the handle bars on my schwinn stingray in a crash 30 years ago .... i did not feel so well either

Which bars do you have?

My bad, that warning is on the carbon seat post literature (Specialized carbon seat post), not the bars. Sorry for my confusion.

back in the day, i remember seeing a number of cracked and smashed up framesets, kestrels and others, but the only broken CF parts i've seen personally in the last 5 years are a couple of seatposts.

i suspect that they were caused by over-tightening. all CF post manufacturers specify how tight you should secure the part (typically a reading in lbs, to use with a torque wrench).

i've been riding an Easton EC-90 CF post for a few years with no problems, and in January of this year, added EC-90 carbon bars.

it's easy to circulate pictures on the internet (did you see the picture of the cracked colnago carbon crankset?) and say "carbon components are unreliable", but i've had zero problems and no one i know personally has experienced any catastrophic failure.

I'd say mostly urban legend, people still have a negative view on carbon fiber, even going as far as calling it "plastic". A properly designed carbon fiber component is MANY times stronger than steel/Al, not even in the same ballpark for the most part. Basically if you crash bad enough to break a carbon bit, a similiar steel/Al part would be so trashed it would be beyond repair as well.

However, as mentioned if you start "cutting grooves" in carbon (from say a handlebar or seat post adjustment) then yes, you will weaken it and the potential for failure goes way up. But that's no different than metal either (it's just a little easier to do with CF).

Also, don't read much into recommended replacement intervals, IIRC most big-name handle bar manufactures recommend changing out Al bars at 2-5yr intervals as well. That's the CYA statement that the legal people want in their literature for the most part.

Andrew

The Cyclists Touring Club did a survey of bar breakages (mostly Al, and not all ultra-light). The conclusion was that bars break mainly in France. Apart from that, there seem to be no common factors.
I wonder, with carbon, if the clamp systems need to be adapted. Principia have specially prepared seat-tube to accept a carbon stem. The slot for tightening is spiral. Maybe stem clamps need to be feathered to distribute the stress.
The use of shims seem to have gone out of fashion with all bars, yet this light, simple system will prevent scoring on the tube.

I wonder, with carbon, if the clamp systems need to be adapted. Principia have specially prepared seat-tube to accept a carbon stem. The slot for tightening is spiral. Maybe stem clamps need to be feathered to distribute the stress.

Easton posts a bunch of warnings on their website about what types of clamps and slots are compatible with their components. Easton also shapes their seatposts and steerers with flat spots to provide for stress relief. I do agree though that a modification of the clamping mechanisms would be a good step too. You just have to treat CF differently but once done, they're perfectly acceptable components... maybe that's what a lot of people are at odds with. While I'm a big fan of CF, I will have to say though that they can be a wildcard. CF is easy to screw up so check the reputation of the manufacturer and the processes they use.

While I'm a big fan of CF, I will have to say though that they can be a wildcard. CF is easy to screw up so check the reputation of the manufacturer and the processes they use.
Don't leave your homes! it's not safe!! :D j/k i've never been a real sure about CF,
especially after this:
http://img78.photobucket.com/albums/v243/elisabethdrooling/tail_assembly.jpg

But in all fairness, this guys cog broke while literally 'just riding along', and it's STEEL!
if i remember correctly, it was only a few weeks old too!!
http://img78.photobucket.com/albums/v243/elisabethdrooling/steel_cog.jpg

Don't leave your homes! it's not safe!! :D j/k i've never been a real sure about CF,
especially after this:
http://img78.photobucket.com/albums/v243/elisabethdrooling/tail_assembly.jpg
But in all fairness, this guys cog broke while literally 'just riding along', and if i remember
correctly, it was only a few weeks old. And it's STEEL! So there really aren't any
absolutes as far as materials go.
http://img78.photobucket.com/albums/v243/elisabethdrooling/steel_cog.jpg

This was due to an improper stem adjustment. He should have gone with less rise, plus, it would look better. :D

This was due to an improper stem adjustment. He should have gone with less rise, plus, it would look better. :D
Oh, absolutely. Why not just ride a recumbent!!!!

That tail assembly failure had been pointed out in a previous thread. The thing is, anything can snap given sufficient forces. Snap a critical flying surface and you will "depart from controlled flight". The question becomes not really that of the reliability of CF in such a case but the stresses involved at the time of the failure. Was the aircraft structure stressed beyond design parameters and by how much?

According to the NTSB report on the testing of the rear attachment lug (http://www.ntsb.gov/Pressrel/2003/031110.htm)...


The test was to demonstrate the behavior of the lug under a load condition similar to that experienced by American Airlines 587 during the accident flight. The load condition used was derived from the flight data recorder information and the subsequent structural finite element analyses.

During the test, the lug structurally failed at a load beyond its design ultimate limit. The test failure appeared to be consistent with calculated failure load analyses performed by both Airbus and NASA Langley. Work is continuing at the Safety Board to continue refining a reliable estimate of the loads on the AA587 fin during the accident.

i'm sure the bike industry is far more comprehensive in their component
testing than the aerospace industry... my point though was that if a
friggin' *STEEL*--not aluminum, but steel cog can split in half, then, well, nothings
perfect and it's not really fair to generalize--unless i should think that all
chrome-moly frames are prone to falling apart? "Like 'no', ok?":)

Aluminum may fail too, but it will bend before snapping giving you some warning. You would think that if a manufacture is telling you to replace the bar or whatever every 2 years then they know something we don't know, and they don't want to be held liable for what they know. Are you reading between the lines here?
That is incorrect. Aluminum will fail suddenly too. It will not bend before snapping.

I replace bars every year or two max. If you are riding sub-200gram bars, you need to follow EXACTLY the manufacturer's recommendations or replace them regularly.

That is incorrect. Aluminum will fail suddenly too. It will not bend before snapping.

I think you may be confusing fatigue limit and ultimate tensile strength for ductility and yield strength. Aluminum will enter a plastic region once stressed beyond its yield strength thus in that sence, it will fail gracefully by bending. However, aluminum also has no fatigue limit thus it is prone to failure at any stress-cycle (S-N) combination on the fatigue curve. In other words, cycling aluminum even under small loads can fail it if you cycle it enough times. Materials with a fatigue limit may be stressed to that point any number of times without failure. Carbon fibre has a very high fatigue limit thus they can typically be cycled at high stresses infinately.

That is incorrect. Aluminum will fail suddenly too. It will not bend before snapping.

Aluminum can fail suddenly, but under normal riding conditions this usually doesn't happen. I had an aluminum fork break on me, but before it broke completely, I know it was damaged for a week before hand.

In terms of frame failure...In normal riding conditions, frame failure is extraordinarily rare. Most cases of frame failure I've heard of or read about occured during high stress situations, such as racing or rough off-road conditions. Average riders usually never experience frame failure.

Re Carbon... I've read quite a bit about it, and the general consensus is that it has great potential that hasn't been realized yet. It's a very new material, so I suspect the design and technological problems will eventually be solved.

Focus people. HANDLEBARS.
aluminum handlebars will fail without warning. Don't talk about aluminum frames when no one else is.

Focus people. HANDLEBARS.
aluminum handlebars will fail without warning. Don't talk about aluminum frames when no one else is.

Regardless, it's a hunk of metal. That hunk of metal doesn't know the difference between being a frame member vs being a handlebar and so the same laws of physics applies. What we're talking about is basically loading a cantilever beam. I would gather that most handlebar failures occur due to fatigue and that aluminum fatigue failures are due to high cycles as opposed to extremely high loads although I suppose it could be a combination of the two depending on how strong the rider is. As someone has already said, many failures usually occur near the stem clamp. This is because the structure is basically a singly supported cantilever with a moment arm somewhere in the range of eight to nine inches for each side. I'm guessing that although many frame manufacturers are designing their bikes so that the amount of load cycles falls well below S-N curve for the expected lifetime of the frame, handlebar manufacturers are not being as conservative. A single high-stress cycle on an aluminum bar can deform and fail it with a bit of bending and warning but high-cycling an aluminum bar can cause instantaneous failures without such warning. As far as CF goes, many good CF manufacturers are adding things like a kevlar mesh that can take up some of the load following a failure at UTS thus mitigating the effects of a catastrophic failure.

Aluminum will fail suddenly too. It will not bend before snapping.

I replace bars every year or two max. If you are riding sub-200gram bars, you need to follow EXACTLY the manufacturer's recommendations or replace them regularly.

If you crash, replace your bars. If you do alot of riding, replace your bars every season or two.
If you buy carbon bars, unwrap them and inspect them carefully regularly. If you crash them, replace them. Follow manufacturer's replacement recommendations.

Re Carbon... I've read quite a bit about it, and the general consensus is that it has great potential that hasn't been realized yet. It's a very new material, so I suspect the design and technological problems will eventually be solved.

Carbon Fiber is not a "very new material" (well if you want to compare it a generic term such a steel or AL it is), design and technical problems have been solved a LONG time ago.

Easton did a great write-up on composites;
http://www.eastonbike.com/downloadable_files/r&d_files/R&D-02%20Composites.pdf

It's a good read without being overly technical or dry and it is bike specific (instead of reading regular specs on a material).

Andrew

All handle bars will break if mistreated but it´s a lot easier to crack Carbon Fiber by overtightening / tightening 4 bolt stems in the wrong sequence . We´ve all seen people crack carbon seat pins like that.
Anyway why pay 3 times as much for a bar with so few benefits over ali ? fashion or flash factor ?