Recently got a carbon framed fully rigid Whippet and it’s been great so far, a nice change from the full suss.

Anyway, most of the riding I’ve done has been gentle trails and light off road but having gone tubeless and fitted some chunkier tyres I had my first ‘proper’ off road ride this morning during which I had a stone strike that felt like a fair old wack. When I got home I inspected the down tube and sure enough there were a couple of marks on the bb shell. Not much more than taking the lacquer off but defo there which got me wondering if it had struck further up the tube, where the carbon is much thinner, would it have caused more of a problem?

Having had plenty of steel and aluminium bikes and dented both on the same sort of ride, how does carbon compare for durability? Have many frames been written off by similar incidents? Am I over thinking it?

Ta.

Yes.

Go and watch Road Bike Party on YouTube and then relax.

Carbon is super tough. And, while it doesn’t bend, it does seem to hold itself together really well even when there are some horrific cracks- certainly long enough to give you plenty of warning before it fails completely

Worth putting something on the downrube for rockstrikes.

See plenty of ibis (ibi?) On the ibis ownersforums who have taken off their rock shields

And had a rock impact split their downtube….

All that said at least with carbon you have. Possibility of repair.

Really depends on how it’s made, what the layup is, type of carbon and epoxy etc etc etc….

Unlike metal bikes – you won’t see a dent.

Very tough and repairable. More than I can say for my body, which takes ages to repair and then still creaks.

Am I over thinking it?

Yes.

There’s a clip on YouTube titled something like “Cannondale carbon vs hammer”. Basically they take a broken frame and attack it with a club hammer to see how easy it is to breaks. The answer is not easily and an ally frame would be pulverised.

Carbon can be really strong or it can be really weak or somewhere in between. It’ll all depend on the lay up, how well it was made, what was it made for (strength, weight, flex, etc) and how good the quality control was at the factory (to weed out crap ones).

I don’t think carbon bikes really like crashing onto hard pointy rocks. No idea about any of those things with the Whippet.

There’s a video on pinkbike somewhere of a visit to the Santz Cruz labs and they’re smashing this frame against a concrete pillar will all their might (amongst other things) – just scratches the paint..

ibis (ibi?)

ibes, I think

smashing this frame against a concrete pillar will all their might (amongst other things) – just scratches the paint..

And yet I have seen a video of Greg Minnaar ‘just riding along’ at Val di Sole when his snaps in half 😀

Here is the video

don’t do that with your Whippet OP

From 5:04

There are many types of carbon fibre, you have different levels of modulus, so stiffness, which can cut down weight, but increase brittleness, you also have many types of weaves, depending on the application, and of course the resin (reinforced polymer) used.

Reality is that a carbon fibre frame can take a big hit without exceeding its limits as the forces are dissipated through the fibres, but many don’t like sharp hits that can penetrate the resin and make it to the fibres.

I like CF, but the way i crash the only place i don’t use it is handlebars!

It depends, is the only honest answer. I’ve seen enough broken carbon frames in my time to be highly cynical of those marketing videos. But it tends to be quite unusual circumstances that destroys them in mtb world outside of normal riding, the bike flying up in the air and by chance coming down on a solid edge will do it. As an early adopter of a carbon race hardtail in the mid 90’s due to a fortunate ex-team deal, I’ve been riding carbon mtb’s a long time and not had any issues…Even after once crashing that early model on a slippery wooden bridge where the edge of the wood chipped a chunk out of the skinny chain stay – in retrospect I should have had it repaired but was young and dumb so never did. I continued to ride it for tens of thousands of rough miles and it never failed, its in the loft and still ridable. Once took delivery of a FS super bike and cashed in its negative karma chips on the second ride when a slate pinged into the downtube, it managed to hit the only mm wide patch not protected by downtube protector. Chipped and visible few mm surface crack, but its been a non-issue as I know the wall thickness in that area is substantial. Broken many more carbon road frames than mtb’s, and had a few repaired, where the repairs have been flawless enough to inspire faith.

Search “broken carbon bike frames”.

Proof. That your anxiety can be increased.

EDIT – keep an eye on it but keep riding.

I have my Fuel ex 9.8 for sale on classifieds (not getting the use out of it as I recently built a hardtail). Had a stone strike, chipped the paint and first layer of carbon just above the BB. Had it repaired last year and sprayed by FibreLyte in the NE. No issues or worries since.

Carbon is easily repairable. The bike market would try and tell you that a new frame is required which is a load of balls. They just want to make money – wise man that repairs carbon.

My friend crashed his road bike into the back of a ambulance (long story) anyhoo ally frame was folded but the carbon fork were perfect not even a crack

In those vids it doesnt work like that. I mean no front end impact is slowed down to take 26 seconds, its a hard fast shock and I reckon that force makes it weaker than the test shows.

OK i’ve no experience in materials testing, but most testing you see of anything involves fast sudden forces acting upon whatever. not slow.

From wiki on carbonfiber

<span class=”ILfuVd”><span class=”hgKElc”>Carbon fibers are usually combined with other materials to form a composite. When permeated with a plastic resin and baked, it forms carbon-fiber-reinforced polymer (often referred to as carbon fiber) which has a very high strength-to-weight ratio, and is <b>extremely rigid although somewhat brittle</b>.</span></span>

So how does sudden shocks impact on brittle materials 😕

@dyna-ti it’s about peak force.

You do realise that you are suggesting something is incorrect while simultaneously admitting you have no knowledge of that subject?

A few years’ back a mate cracked the downtube on his Scott Spark on a notoriously gentle flat 11km xc loop. No idea what hit it, because it’s a gentle track – my kids rode it aged 4.
It made us all laugh because he normally rides DH and sends it like he’s 20. He got it repaired and made a kydex protector to stop it from happening again.

OK i’ve no experience in materials testing,……………………
So how does sudden shocks impact on brittle materials 😕

Firstly I’d go look up a materials engineering definition of brittle, it isn’t related to strength.

“A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a sharp snapping sound.”

I.e. it breaks rather than bends, but that tells you nothing about the force required to achieve either. All it means is that when you do ride it headfirst into a tree/car/wall/the ground the frame will crack into pieces rather than bend.

Carbon fibre can be incredibly strong no doubt. It can also fail in unpredictable and spectacular fashion. We don’t ride bikes in a lab we ride them in the real world where anything can happen.

What I especially don’t like is that carbon can save up damage for the future. You can crash it and it’ll look perfect but you have no idea how much it’s been weakened.

My friend crashed his road bike into the back of a ambulance (long story) anyhoo ally frame was folded but the carbon fork were perfect not even a crack

That’s the problem. They’ll look perfectly fine until they snap off.

A mate of mine almost died recently when his carbon handlebar sheared off on a slightly lumpy bridleway. Two years of riding and crashing, no signs of damage and then bang. Enormous accident at high speed in a place where you’d least expect your bike to break.

Depends on what form your carbon is in!

Diamond is carbon – very tough.  Graphite is carbon, very soft  Coal is (mainly) carbon – sort of like a soft rock

I wouldn’t worry about a carbon frame any more than I’d worry about a metal frame.

I own a carbon fibre Orbea wild family
Had zero issues with it yet loads and loads of the Alloy frame riders are having their frames snap frequently

I wouldn’t fret about it. But like all things, it can and likely will break at some point. Could be within 1 year, but most likely you will get many years out of it and it will get steadily scuffier/chipped etc but be fine until it is very old.

Mtbs over the years:
1 carbon frame broken out of 2. Seat tube/ bb area cracked through.
2 steel frames broken out of 4. 1 headtube came off, one was hit by a road-sign.
No alu frames broken out of 6 so far.

@cheekyget – I got t-boned but a car, the carbon fork was totalled (visibly flopping around) and the alloy frame was fine. Just depends on where the impact is and whether the frame of fork is designed to adsorb that or not.

I’d hope that any CF mtb has sufficient material around the BB to cope with loads of rock strikes.

Thanks for the responses all, everything said makes sense and I’ll stop worrying about a potential rock strike that may, or may not happen and if it did may, or may not cause any damage if it managed to hit a very specific part of the frame, which has not happened yet!!

Mentioned this on here before me and my carbon Tallboy crashed into a ravine in Morocco, which included a 6ft drop and rolling down big sharp rocks. The frame was unmarked despite slamming into rocks. By way of contrast, I was quite heavily marked.

That describes the biggest problem with carbon though…the frame may be unmarked from the outside but could easily be damaged on the inside and significantly weakened, with the possibility of failure down the line. At least with metal frames one can inspect them and when you find a crack or a dent you can point to it and say ‘oh look it’s damaged’- and if it looks fine, you can say with some confidence that it’s fine. With carbon you never quite know. Which is why I always cringe packing a carbon bike away for flying in a frame bag as you never know whats happening to it out of your sight, at least when you’re riding it in normal conditions you have an idea of the impacts its accumulating.

but could easily be damaged on the inside and significantly weakened

There’s a You Tuber I follow – Vancan, who’s recently had to return a couple of carbon frames (He does some pretty wild west coast BC riding, so it’s not like Sussex Downs, y’know?) Anyway, both times resulted in a visible crack.

What I mean is, do violent things on bikes and you run the risk of them breaking regardless of what they’re made from. I think for normal UK style riding that most of us do, you shouldn’t overly worry about frame material.

I think worrying about plane handlers and your bike – frankly has less less to do with the bike frame material and more to do with what’s going on inside your head. That way lies madness, either pack it up forget about it and enjoy the holiday, or rent when you get there.

What I especially don’t like is that carbon can save up damage for the future. You can crash it and it’ll look perfect but you have no idea how much it’s been weakened.

That you can say for aluminium tubes, for sure. Enough cyclic stress and they’ll split, and that limit is lower with aluminium. They don’t like sharp edges much either

I think worrying about plane handlers and your bike – frankly has less less to do with the bike frame material and more to do with what’s going on inside your head.

Not really. I’ve flown with bikes a lot, and seen what can happen. Once had an amusing incident at the collection gate involving a bike bag and a heavy automated metal barrier which would be hard to believe unless you saw it, which I did. Had the bike been carbon it would have been crushed to bits, luckily it was Ti, which is much better for frequent flying…pretty sure my head didn’t just imagine it…I’ve still flown with carbon bikes a lot, but go to town on the packing.

The point is, because damage is not always visible – it’s what’s occurring when you cant witness it that becomes elevated. Either in that situation or when it’s barrelling down the trail behind you. If you’ve nerfed it hard enough when actually on the bike you’d certainly be aware of it.

That you can say for aluminium tubes, for sure. Enough cyclic stress and they’ll split, and that limit is lower with aluminium. They don’t like sharp edges much either

I know everything breaks but the point is that there’s a huge difference in how the failure happens and it could be the difference between a small tumble and a fatal accident.

I’ve broken plenty of alloy frames and they all started letting go with lots of warning signs.

Have we re-wound to 2005?

In 2022, you have nothing to worry about on any mainstream carbon frame!

And remember, the onyl way to actually know which is stronger in any given circumstance is to crash both a carbon and an ally frame in an identical way, which never happens. Anyone posting, “oh, but i broke my …..” is i’m afraid to say, irrelevant, because they are a sample size of one. So yes, perhaps your ally or carbon frame did, or did not break, but unless you repeat it with the other material frame and see what happens, that’s not actually useful info!

Buy the bike you like, and get out and ride it, and that’s er, it, really 🙂

A mate of mine almost died recently when his carbon handlebar sheared off on a slightly lumpy bridleway. Two years of riding and crashing, no signs of damage and then bang. Enormous accident at high speed in a place where you’d least expect your bike to break.

I almost died had a small crash when my aluminium handlebars failed on a gentle section of Glentress red run. Two years of riding and crashing, no signs of damage and then phut.