Carbon handlebar durability

Thinking about getting a new bike (well frameset cause I have the groupset and wheels already by transferring from my old bike) and was windering what handlebars to use. Test road an SL7 tarmac and thought the Aerofly handlebars were very comfortable as it made the cracks in the asphalt seem much smoother and the slight sweep forward made the tops a bit nicer too. But I don’t have any experience with carbon handlebars other than seeing the scary pics of how they can fail.

How durable are carbon handlebars? As in, if my bike falls on its side do I have to worry about the structural integrity of the bars? Not a crash with something while the bike is moving, just a simple fall.

There is a tendency to think of CF as something more fragile than metals It isn’t. What it is, is something far stiffer. So when it breaks there is no preliminary bending. It just goes. It is also almost immune to fatigue. Repetitive cycling of metal creates tiny cracks then grows them to the point of failure. Some metals are more susceptible than others. Aluminum is right up there. So on a like for like basis CF is tougher than metals. It is how it is used that leads to the notion of fragility. We can make tubes with CF far thinner than comparable metal ones. More often than not the limit for the metal is not the design loads but manufacturability. We can’t handle metal with very thin walls.

So the long answer short. The bars will either work or break they are unlikely to carry damage then suddenly fail mid ride. Although in general with bars the tape can mask damage but not that much. As they are engineered to the same standards as metal bars they should manage the occasional mishap with ease.

1 Like

thanks for this, I have carbon bars and was wondering about wether they would ever fail mid ride or not, which does make me nervous occasionally!!

I’ve only ever had 2 cases of sudden and unexpected failure on the bike and both involved a metal part! Had a saddle bolt snap on me mid-corner, with the saddle flying right off the bike, amazingly survived that one without either crashing or impaling myself on the seat-tube, though cycling the remaining 10 miles home without a saddle wasn’t much fun. And had an aluminium bar snap clean off at the stem as a result of metal fatigue. It was an older bar which was narrow diameter for the whole length, unlike ones made in the last ~15 years which bulge in the middle. Didn’t come out of that one so well, was in the drops when it happened so supporting most of my upper body weight through my arms, crashed pretty badly and ended up with a number of separated ribs and a lot of missing skin!

I don’t think carbon would ever fail from fatigue, it could do if it was damaged in a crash or a drop and you carried on riding it. So as long as you look after your bike and get it properly checked out if you crash it then should be fine.

I’ve been using Bontrager, Niner, and Enve bars on a mix of road, gravel and mountain bikes for years with no issues whatsoever. I’d don’t have a Specialized bike but would be really confident in their products too based on their reputation.

I did have a carbon railed saddle snap on a mountain bike once. It was just a sudden “crunch” as I put weight on the saddle while riding, and the rails snapped. Digging deeper at the time others have reported failures on some mountain bikes with carbon saddles, but it seems brand specific. I believe it happened to one of the hosts of the Leadville Podcast as well. I’ve since ridden carbon railed saddles and had no issues.

I always thought this was a bit of a myth. Just check some youtube videos of people purposely trying to destroy carbon frames, wheels, bars etc.
First it’s harder than you think. Second, there usually is a lot of cracking first and the items in question become kinda wobbly since the hard, rigid resin disintegrates and the flexible carbon fibers hold the weight. So I think carbon parts fail a lot more gradually than a lot of people seem to think. I think you generally would notice it quite soon.

It’s less a worry about the sudden nature of failure and more the worry that if my bike falls on it’s side is the chance of the bars being broken tiny like now or is there a real chance that I need to replace them. (I.e. a new high cost item that will need replacing more often when I never had aluminum bars break)

Correct but the point is they do not bend and deform in a gradual way. The either work fine or they have already failed as you described. It’s hard to miss unlike a metal fatigue failure.

@enki42 I ride carbon bars. I don’t know if there is any way to quantify “how durable” compared to aluminum but, certainly many of us who have been around since the 80’s and even earlier, would probably say aluminum is more durable or maybe less fragile but, both are durable enough.

I’ve always wondered why people buy expensive carbon to save weight. Not that this is your case but, if it is and your not expressing it, the weight savings is pretty small.

Dampening as you wrote feels smoother and I totally agree. This is one of the main reasons I use carbon bars. That and the shape that can be made with carbon is much wider.

Two main things with carbon bars: 1) buy a torque wrench so you don’t over tighten. 2) I would not recommend buying off brand cheap far east carbon parts. Stick to the more expensive name brands.

Lastly, if you are going to go down this rabbit hole consider what your bars are attached to. Again, no over tightening to the steerer and no cheap off brand carbon forks.

1 Like

Weight doesn’t matter at all and I wouldn’t mind if they were heavier. When I test rode the tarmac with their carbon bars it just made the handlebars feel very smooth (I was searching out cracks on the road to test for comfort) so felt a bit better then my current bike. (My current bike has https://redshiftsports.com/shockstop-suspension-stem installed on it) Its purely about comfort. Ok a bit of the aerodymic advantage, but only to justify $300 for the handlebars from specialized when regular handlebars are so much cheaper.

I take it your bike has fallen on its side and no issues at all from that? Thats the durability I’m worried about, not riding as that is nor the normal use case. I assume Specialized tests the normal use case enough that they wouldn’t use handlebars that would fail in that way (Also not as heavy as some with specialized not having a weight limit and don’t pull on them as much as other riders)

Anyone work in a bike shop? How often do you see carbon bars needing to be replaced?

2 Likes

My carbon frame Cx bike with carbon bars has been crashed dozens if not a hundred times at various speeds and have not broken yet. Meticulous inspection and paying attention to signs of failure are key. It hardly ever fails suddenly without warning since the parts are made up of layers of fiber glued together

That’s correct.

1 Like

This is the key bit. The frame is a thin shell construction. Unlike the bars, forks and seatpost. They are thick wall. So it, the frame, can suffer a fracture from load on undetected damage such as delamination. Here’s the thing though the frame has multiple pathways for the force and CF is damned strong. So a catastrophic failure is pretty unlikely. Those stories about guys finishing races with bust seat stays; not really exceptional for the frame.

Carbon bars won’t break from the bike falling over. They are not brittle plastic.

When fitting some new carbon bars last year, my heart broke when I put the stem face plate on unevenly and noticed a crack radiating from the clamped area of my brand new unridden bars!!

So watch out for that, and learn from my mistake even though you may be using a torque wrench, putting the face plate on one bolt at a time can imprint a pointy part of the stem plate into the bar.

Stubbornly, i’ve been riding these bars for a year and a half now, and the crack hasn’t become any larger.