How safe are carbon handle bars?

miurasv

http://www.bikeradar.com/forums/viewtop ... t=12708977


Was reading Rokkolas thread, link above, and am wondering how safe carbon bars are? Do they fail, crack or split often? I must admit to thinking about how strong they are before. I don't know why, and I'm sure I'm wrong in thinking it, but I always seem to think of carbon as a brittle material. Bars failing really could cause catastrophic/fatal/life changing consequences.

dennisn

FWIW I don't have carbon on my bike for a couple of reasons. I simply don't trust carbon seat posts like I trust aluminum ones. I don't have any carbon components on my bike
because they cost more yet don't offer any advantages(other than bling) over aluminum.
Oh, I suppose that in a few cases weight could be an issue(if you're a weight weenie).
Anyway, since I'm neither a showoff(well, maybe a little) or concerned about the weight difference between an aluminum part and a carbon one I do without the "must have" stuff.

dennisn

There is another post in Road Buying Advice that has some carbon bar safety issues being discussed in it----

Alloy Bars Quick Purchase Needed

graeme_s-2

If you trust your carbon forks, then I don't see why you wouldn't trust carbon bars as well...

miurasv

http://www.youtube.com/watch?v=nvk63bmVpck


I also found the above very interesting. A strength comparison test between carbon, steel and aluminium frames.

sheffsimon

I wouldnt use carbon bars, not because I think they might break and cause me to crash, but I think that would be prone to breaking if I did hit the deck.

Of course, this might be total boll***ks.

Also cos they cost a packet......

dennisn

miurasv wrote:

http://www.youtube.com/watch?v=nvk63bmVpck


I also found the above very interesting. A strength comparison test between carbon, steel and aluminium frames.

While interesting to watch I'm not sure anything that had anything to do with strength of bicycle frames was actually "proven", so to speak.

miurasv

dennisn wrote:

miurasv wrote:

http://www.youtube.com/watch?v=nvk63bmVpck


I also found the above very interesting. A strength comparison test between carbon, steel and aluminium frames.

While interesting to watch I'm not sure anything that had anything to do with strength of bicycle frames was actually "proven", so to speak.

Well in the given tests carbon lost big time however those tests aren't relevant to road riding conditions where different stresses entirely are placed on the frames. I hope!

dennisn

miurasv wrote:

dennisn wrote:

miurasv wrote:

http://www.youtube.com/watch?v=nvk63bmVpck


I also found the above very interesting. A strength comparison test between carbon, steel and aluminium frames.

While interesting to watch I'm not sure anything that had anything to do with strength of bicycle frames was actually "proven", so to speak.

Well in the given tests carbon lost big time however those tests aren't relevant to road riding conditions where different stresses entirely are placed on the frames. I hope!

+1......Different materials react to different tests in different ways. I'm sure tests could be designed to "prove" any of the materials is better than any of the others.

calvjones

Graeme_S wrote:

If you trust your carbon forks, then I don't see why you wouldn't trust carbon bars as well...

Very true. However, my mate ended up with a blood clot on his brain after his carbon forks broke after riding through a pothole. I can't speculate on why it happened but :shock:

Still riding mine but only because I'm not sure what to substitute them with.

Monty Dog

I've broken steel and alloy forks - never had a problem with carbon.

Carbon bars are only a problem if they get crashed - but likewise, many lightweight alloy bars aren't too tough either. I've had carbon bars and stems, but stick to alloy these days as I don't see any advantage - just a serious dent in your wallet.

You could spend hours on the web browsing for those 'just riding along' stories where components fail for 'no apparent reason', but I've been working with composites and lightweight materials for enough years to know that >99% of problems are down to 'operator error', abuse or mis-use

miurasv

Monty Dog wrote:

I've broken steel and alloy forks - never had a problem with carbon.

Alloy and steel don't seem to fail to the extent that carbon does. Did your forks actually snap or break into two like carbon does when it fails? Just asking out of interest.

calvjones

Monty Dog wrote:

I've broken steel and alloy forks - never had a problem with carbon.

Carbon bars are only a problem if they get crashed - but likewise, many lightweight alloy bars aren't too tough either. I've had carbon bars and stems, but stick to alloy these days as I don't see any advantage - just a serious dent in your wallet.

You could spend hours on the web browsing for those 'just riding along' stories where components fail for 'no apparent reason', but I've been working with composites and lightweight materials for enough years to know that >99% of problems are down to 'operator error', abuse or mis-use

well, yes, but sure operator error (e.g. over tightening, scratching) is more likely to lead to catastrophic failure on carbon than on steel or alloy?

I ask as a non-materials engineer.

miurasv

Imagine your forks or bars fail which forces you into the path of a car or lorry (any vehicle) coming the other way. You're not going to be around to tell what happened. The accident will be blamed on rider error as the bars or forks will be thought to have broken by the impact with the other vehicle.

gabriel959

I use carbon bars (the cheap zipp ones that were sold over xmas). I absolutely adore them, they are very stiff, but more importantly very comfortable and quite light. If I ever crash though I will replace them.

dcl10

I’ve used (and broken) two carbon bars over the last 12 months in races. The first, 3T Rotundo LTD’s sheered off at the stem after hitting a steel crowd barrier during a crash. I read a lot of reviews and it seemed like the ZIPP SLC2’s are supposed to be the strongest carbon bars, so I replaced the 3T’s with those. Went down in a fairly minor crash last month, got up and finished the race but noticed my right drop was flexing like crazy. Took a look after the race, and the shifter body had punched a hole through the carbon. The clamp area was also somewhat damaged, although this might only have been cosmetic. Replaced those with Rotundo Pro’s. They are heavier, but more durable and noticeably stiffer. To be honest I doubt a carbon bar is just going to fail on you unless its already taken some damage and you have not noticed. So safety wise I would not be terribly concerned, but from my experience they do not make much sense if your racing competitively. If you’re a recreational rider who likes high tech equipment and does not go down too often I think you’d be fine.

gabriel959

dcl10 wrote:

I’ve used (and broken) two carbon bars over the last 12 months in races. The first, 3T Rotundo LTD’s sheered off at the stem after hitting a steel crowd barrier during a crash. I read a lot of reviews and it seemed like the ZIPP SLC2’s are supposed to be the strongest carbon bars, so I replaced the 3T’s with those. Went down in a fairly minor crash last month, got up and finished the race but noticed my right drop was flexing like crazy. Took a look after the race, and the shifter body had punched a hole through the carbon. The clamp area was also somewhat damaged, although this might only have been cosmetic. Replaced those with Rotundo Pro’s. They are heavier, but more durable and noticeably stiffer. To be honest I doubt a carbon bar is just going to fail on you unless its already taken some damage and you have not noticed. So safety wise I would not be terribly concerned, but from my experience they do not make much sense if your racing competitively. If you’re a recreational rider who likes high tech equipment and does not go down too often I think you’d be fine.

Indeed, that is why I am not using them for racing, just for my sunday / sportif bike. If they fail I am getting some 3Ts

synchronicity

dennisn wrote:

miurasv wrote:

dennisn wrote:

miurasv wrote:

http://www.youtube.com/watch?v=nvk63bmVpck


I also found the above very interesting. A strength comparison test between carbon, steel and aluminium frames.

While interesting to watch I'm not sure anything that had anything to do with strength of bicycle frames was actually "proven", so to speak.

Well in the given tests carbon lost big time however those tests aren't relevant to road riding conditions where different stresses entirely are placed on the frames. I hope!

+1......Different materials react to different tests in different ways. I'm sure tests could be designed to "prove" any of the materials is better than any of the others.

Truer words have not been spoken.

And from whatI have seen, this whole "catastrophic carbon" failure mode is greatly exaggerated. Actually if you watch tests being done in a Materials lab under astm conditions (for example), CF often fails in stages. Anecodotal evidence that it's all bollocks: I have seen alloy fork steerers & seatposts completely snap in two. At least when CF fails, there are sometimes various parts holding it together..

neeb

I'd be more worried about lightweight alloy bars failing for no apparent reason than carbon ones - aluminium fatigues, carbon shouldn't unless it's stressed beyond its limits. But maybe carbon bars are more likely to break if subjected to a hard impact (i.e. crash). I'd certainly always inspect the bars very closely after a crash and replace if in doubt.

I like the taught springy feel of carbon bars, but there's no real other advantage.

Chicago Dave

carbon fiber has a life span. when reached,it breaks without warning.
when you tighten the extension,you really really need to use a torque wrench.
all this,to save an amount of weight equal to a mouthful of water.

Pro's get new bits all the time. Do you? Gonna hae these awhile?

Alu...or sudden failure. your choice

Chicago Dave

And from whatI have seen, this whole "catastrophic carbon" failure mode is greatly exaggerated


yea,ask Georgie 'bout his steerer tube,,,

[Tim]

Chicago Dave wrote:

carbon fiber has a life span. when reached,it breaks without warning.

Complete rubbish.

neeb

[Tim] wrote:

Chicago Dave wrote:

carbon fiber has a life span. when reached,it breaks without warning.

Complete rubbish.

Yup, almost the opposite of the truth. It's actually aluminium that has a life span based on fatigue. As long as you never stress it beyond its limits carbon should last forever. But crashing it or squashing it by doing the stem bolts up too tight is likely to stress it beyond its limits. So if you think you are going to do this, get alloy instead.

ADIHEAD

Monty Dog wrote:

I've broken steel and alloy forks - never had a problem with carbon.

Carbon bars are only a problem if they get crashed - but likewise, many lightweight alloy bars aren't too tough either. I've had carbon bars and stems, but stick to alloy these days as I don't see any advantage - just a serious dent in your wallet.

You could spend hours on the web browsing for those 'just riding along' stories where components fail for 'no apparent reason', but I've been working with composites and lightweight materials for enough years to know that >99% of problems are down to 'operator error', abuse or mis-use

Sounds about right. I've spoken to loads of people with cerca 2005 Treks who've had bars break. Anyone else heard similar?

neeb

yea,ask Georgie 'bout his steerer tube,,,

Which was aluminium, as it happens... :roll:

inseine

Sounds about right. I've spoken to loads of people with cerca 2005 Treks who've had bars break. Anyone else heard similar?

I think it was only the Modone 5.9 that had carbon bars back then. I'm surprised you know 'loads' of people who had that bike, let alone that the bars broke. Surely a sample like that would mean there were thousands of these things breaking around the world?

graeme_s-2

Just for the record, I've only ever had alu bars, and I've broken one set. I was deliberately brake tested by a driver who served in front of me at about 25 mph. My front wheel hit his bumper and I went over the handle bars, landing on my head and right shoulder. I then fell to the left, and this relatively gentle sideways fall folded the left drop flat against the top of the bar.

My carbon forks were fine mind

on-yer-bike

Many stems have sharpish edges on the clamp area and face plate. These should always be rounded off before clamping the bars.

I have see top end Ritchey carbon bars snapped in half, where the right lever was clamped on, as a result of going over a bump. Levers have to be clamped on tight.

racingcondor

Two reasons why I wouldn't buy carbon bars -

1) Bars are going to hit the ground in a crash and I'm overly paranoid about carbon. Before anyone says it, yes I know Alu is also perfectly capable of breaking unexpectedly after a crash, but like I said, paranoid.

2) The weight saving on most carbon bars is almost nothing compared to a good Alu bar so I just don't see the point in spending 3 times as much.

Honestly though, if I buy a bike with carbon bars I'll be very happy to ride them. Unless they've been crashed I really doubt there are any problems with modern carbon bars.

@ on-yer-bike. Shimano torque specs only ask for 6-8 Nm on the clamp bolt. Sounds a lot like poor installation to me.

cougie

1. Carbon bars only weigh about the same as alloy.
2. Alloy bars are a hell of a lot cheaper than carbon.
3. Sharp edges on the stem bracket need to be sorted before fitting carbon bars.
4. If your bike even as much as falls over - the bars take a smack. I dont want to have to replace an expensive part very often.

synchronicity

[Tim] wrote:

Chicago Dave wrote:

carbon fiber has a life span. when reached,it breaks without warning.

Complete rubbish.

Yes, it's uninformed statements like those that create & reinforce common misconceptions.

For the record, individual carbon fibres break without warning. Yes it's possible to test an individual fiber on a micro-scale tensile testing machine. The ones we tested for an undergraduate composites class at uni all broke around about 10 - 20 Newtons force (1 gram).

But when you put tens of thousands of fibres into a weave with a polymer matrix and then test the 'composite', yes all of those individual fibres break when their individual [different] stress levels are reached. It ends up being a question of statistics, with the majority breaking at the average Ultimate Tensile Strength (UTS). Think of a bell curve, with some weaker fibres breaking first, then more and more and more until a peak is reached. Then even after the UTS is reached, there are still intact fibers holding the thing together... So you can know for example when a composite is starting to fail. You can even hear it. Sure this happens at a slower strain rate, but honestly, it sh¡ts me when people speak about things they do not know.

On the other hand, some brittle metals for example cast iron will truly fail without warning.