Not paying attention and have overtightened a stem bolt whilst installing a new Easton EC70 carbon riser bar! Aaarggghh!. Set up my torque wrench wrong and heard the dreaded crack. Cant see any obvious damage but there are some small indents where the lower stem bolts have pinched. Do I risk riding it or is it destined for some catastrophic failure!

If you heard a crack, yep it's fecked 😥

Bin it.

Bin now or hospital later?

Cut it into 3 or 4 lengths and make a wind chime.

the noise was your wrench reaching the torque! well we can only wish!

be honest and tell the shop/distributor what has happened. you might be lucky and get the option of buying another at a crash replacement/trade price.

What Martin said. Torque wrenches, eh?

I still can't believe people use something seemingly so delicate on a bike that gets (or should get) thrashed off road!

I still can't believe people use something seemingly so delicate on a bike that gets (or should get) thrashed off road!

I agree, and as for F1 cars and supercars being made of the stuff and getting thrashed at 200+mph, why would they do that!! 🙄

Oh well.

i rock dropped on to a pair of ritchy WCS i had whilst in the alps. a few deep gouges appeared, and i remembered why i vowed never to use carbon again. my superstar carbon post got squashed a couple of years back, and another carbon bar developed blister like things near the clamp. for me, its just something to worry about, with no real benefit (that i can find).

I agree, and as for F1 cars and supercars being made of the stuff and getting thrashed at 200+mph, why would they do that!!

Because F1 has a practically bottomless pit of cash, so it doesn't matter if a wishbone is binned after every race?

As for supercars, the carbon is mostly used in places where it shouldn't get a battering, and again, the maintenance schedule is way beyond what a bike will get.

Bin them, seriously don't take the risk, sorry to hear your mistake.

As for those that question carbon fibres strength, better not get on any aircraft – Carbon wings, fuel pipes, transmission shafts….. the list goes on. Safety critical components tested to the life of the aircraft.

As for those that question carbon fibres strength, better not get on any aircraft

And again, not on a maintenance and inspection schedule anything like that of a bicycle. Any impact on any part of the aeroplane and they'll be giving it a serious inspection, and possibly replacing it.

I agree, and as for F1 cars and supercars being made of the stuff and getting thrashed at 200+mph, why would they do that!!

Well if carbone is sooo super good off road, why MX bikes (with almost bottom less money pit) aren't made of the stuff?

I know some people that manage to break anything (including a race face turbine crank) have used carbon bars for years with no problems.

But I just cant. That's it call it irrational fear, I just cant. And the fact that easton don't produce any motorbike related product tell me something.

if you didnt rely on the torque wrench so much then it wouldnt have happened

did you not think "hmmm im using a bit much pressure here i should maybe check"

or just racked it up waiting on the click from the torque wrench

most home mechanics torque wrenches are about as much use as a chocolate fireguard anyway.

by all means use em but relying on them solely is fools folly

Classifieds

Wot trail rat said…..

What you could do is, ride on it til it breaks in half- which won't take long at all, it's ****ed, sorry- then post it on Bustedcarbon so people can say "Oh, carbon fibre's so weak!"

" trail_rat – Member

"if you didnt rely on the torque wrench so much then it wouldnt have happened did you not think "hmmm im using a bit much pressure here i should maybe check"

Sounds harsh but it's 100% true.

Windsurf masts are made of carbon and the accepted way of clamping the boom so it doesn't slip is to tighten it until you hear the creak.

They handle a lot of load and seem to last for ever.

"Windsurf masts are made of carbon and the accepted way of clamping the boom so it doesn't slip is to tighten it until you hear the creak.

They handle a lot of load and seem to last for ever[/quote]bigjohn

I have been sailing for years and have never heard that , and I havent had problems with booms slipping for at least 15 plus years. Carbon is great but fragile if abused

Not had a problem using carbon bars either and they take quite a bit of abuse. My mates carbon seatpost has a crack in it near the clamp, he's been riding it like that for months without any bother

Brave or foolish?

Wot trail rat said…..

crack or creak?

Before you bin them, I know that Easton can check them for you.

juan – Member
I agree, and as for F1 cars and supercars being made of the stuff and getting thrashed at 200+mph, why would they do that!!
Well if carbone is sooo super good off road, why MX bikes (with almost bottom less money pit) aren't made of the stuff?

I know some people that manage to break anything (including a race face turbine crank) have used carbon bars for years with no problems.

But I just cant. That's it call it irrational fear, I just cant. And the fact that easton don't produce any motorbike related product tell me something.

Don't want to completely piss on your bonfire but, mx bikes don't use carbon frames because there is production rules in both FIM and AMA sanctioned races. The bikes have to start from a production chassis (these are later modified to a degree that makes them so far removed from the original that makes you question the rule but hey!) The mx community was in uproar when the new YZ450 came to over £7000 so carbon parts won't be appearing any time soon (not to mention that KTM, Husqvarna and others still use steel frames and they are still a comparable weight.) Also actual weight weight isn't as much of an issue as perceived weight the new KTM350 is actually heavier than some of the 450s (Honda being the lightest) but it rides lighter due to it's lower displacement/ less inertia from the engine (hence why a 250f is less tiring than a 450 despite their only being a few kilos difference.) Finally Easton do produce a set of motocross bars, corresponding clamps, grips and grip doughnuts. They are notably used by star racing Yamaha in the US and Mat Rebaud for FMX. They aren't carbon though. Carbon is used quite extensively in high end after-market exhaust systems (Leo Vince, Akrapovic etc) as is titanium, this is probably more for the bling factor than performance (as is the exhaust usually!)

Iain

Are your pinch bolts quite 'dry'?

I have a Thomson stem and ALWAYS get this dry crack noise when tightening the bolts back up (alu bars). Doesn't necessarily mean you've cracked your bar IMO.

Bolts are pretty dry tbh and I'm not completely convinced I've written it off. I'm just being super cautious because it's carbon. As I say I can't see any significant damage, but again carbon doesn't always show damage before it fails. The torque wench was set to 5nm but I didn't realise it's not effective until 10 – stupid mistake i know! not sure whether this is enough to crack a decent quality bar?? I didn't even get to the click because I was suspicious…

Why don't you clamp them in again, grab hold and try and break them. If they withstand that then ride them.

I have a Thomson stem and ALWAYS get this dry crack noise when tightening the bolts back up (alu bars).

Bit of copper slip on the bolts solves that…always done that on my Thomson stems.

"there are some small indents where the lower stem bolts have pinched" doesn't sound good at all. But 10nm isn't so much that I'd be assuming they're dead, your earlier post made it sound like they'd been massively overtorqued.

Buy one of these:

http://www.winstanleysbikes.co.uk/product/27096/Ritchey_5Nm_Torque_Key

And tbh I find that I don't tighten enough to hear/feel the 'click'.

WTF does anyone need a torque wrench for assembling anything on a bike. A bit of common sense and mechanical sympathy will get you a long way, well at least a lot further than relying on a uncalibrated or badly set up torque wrench.

I always normally do these sort of things on 'feel' this time I thought I'd try and do if 'properly' oh well, I'll se how I get on. If I post a picture of me with half a carbon handlebar sticking out my head you'll know it's not gone well…. Seems like a sound investment that torque key

Do a search for Carbon bars on SDH – there's a recent thread on it with some input from an F1 Materials Technologist – if he says don't use carbon bars (and he does) I wouldn't. It's the wrong applications for the material and simply not worth the 50? gramme saving over a decent ali bar.

Ah, well lets face it. Its on thing that if it fails you are most certainly falling off your bike asap at any speed.

I've donr this in the past, brand new carbon bar – crack! Ended up with indents as you describe.

Bin them and never go near carbon bars again! well thats what I did

EC90 = 135g
EA70 = 265g

Claimed weights.. weightweenies would give a better idea.

So it's a reasonable weight saving. I've used USE Atoms for a few years now and they weren't installed with a torque wrench or owt. Not recommending that, but the bars are pretty tough.

That said, the method and result of possible failure has made me go back to Thomson seatposts off road. Not sure how you judge the torque on a QR??

PS – I wouldn't use them if I'd heard them go crack. No sir.