Who would have thought it. Pretty impressive stuff from Santa Cruz.

Santa Cruz Alu v Carbon Fibre

After watching that I think I will be going for the Carbon option rather than aluminium given the choice.

it required an extra 585lbs of energy

oh dear….

One thing I’d be really interested in – how sound is the frame they walloped off the concrete at the end? I think most people accept carbon fibre’s strength – what people tend to question is whether it maintains integrity after impact damage.

When Niner tested their CF fork by bashing it with a hammer, they then put that same for through the same destructive test cycle they use for new, and it passed – but they never showed that in the video.

Would love to have seen that last frame back on the jig.

ir_bandito – Member

it required an extra 585lbs of energy

oh dear….

E=B^2 where B=Butter

To be fair I think both bikes are bloody tough and in the real world would you ever break a aluminium Nomad? However it’s good to see as it kills off all those people that say carbon is so fragile if it gets hit by a stone. Couldn’t believe how tough that carbon frame is getting smashed against a concrete block.

the problem is all those people in the test facility and potentially anyone who watched the video and saw the carbon break will be at risk of carbon shard inhalation which will eventually spread to their brains and cause a long and painful death

Interesting to note the alloy frame failed at the hydroformed bend prior to the head tube junction. Obviously, being able to lay up and strengthen carbon at key weak points allows Carbon to be much more applicable to complex shapes and still retain the strength whilst managing weight effectively, using less material where necessary.

It also re-enforces that good old engineering theory that a straight, round tube is generally the strongest type to use if you can.

Not quite the same test as a sharp rock either.

I am not biased by the way. No issues with carbon. They use it in aircraft=probably ok 😉

They use it in aircraft=probably ok

They also use pasta in aircraft (meals) but I wouldn’t want my bike made out of it ;-P

(would have a carbon one though)

will be at risk of carbon shard inhalation which will eventually spread to their brains and cause a long and painful death

I’m sure most people inhale worse things on a daily basis and know nothing about it. I wonder how much asbestos I’ve breathed in over the past 38+ years at work 😐

Interesting to note the alloy frame failed at the hydroformed bend prior to the head tube junction. Obviously, being able to lay up and strengthen carbon at key weak points allows Carbon to be much more applicable to complex shapes and still retain the strength whilst managing weight effectively, using less material where necessary

Is this totally a good thing though ? Its great for pure XC machines but for everyday use ?

I did see the NOMAD concrete block test and the frame does appear strong in all directions, but the temptation will be to leave some areas of the frame very thin to save weight surely if these get hit then the frame may easily damage ?

So why have they made the carbon Nomad so much stronger than the alu version?

In the blurb, they reckon that the worst frontal impact would rarely exceed 800lbs, but the alu frame is good for almost 1500lbs.

The carbon one is soooo far beyond their assumed max load that it could have been made adequately strong for the job, but lighter.

I am not saying that it’s a bad thing, of course, stronger is better in general. But, if they are confident that the alu frame is strong enough, why not make the carbon one just as strong, but even lighter….?

stumpy01 – Member

if they are confident that the alu frame is strong enough, why not make the carbon one just as strong, but even lighter….?

Easy to make CF as strong as aluminium in one direction – extra material needed for impact and other forces.

a long and painful death

Death is indeed long, but I’m not convinced it’s painful.

They use it in aircraft=probably ok

A380 is holding up well isn’t it? oh no…..that’s not right is it? I’ve got it, they all need inspecting for cracks.

sam_underhill – Member

A380 is holding up well isn’t it? oh no…..that’s not right is it? I’ve got it, they all need inspecting for cracks.

Yeah, cracks in the aluminium bits, I thought?

sam_underhill – Member

A380 is holding up well isn’t it? oh no…..that’s not right is it? I’ve got it, they all need inspecting for cracks.

stumpy01 – Member

Yeah, cracks in the aluminium bits, I thought?

Yep cracks in the aluminium brackets not the carbon. Good try though 😆

I stand corrected.

Should have made more bits out of carbon then I guess.

http://www.euronews.net/2012/02/06/boeing-plays-down-787-delamination-problem/

For those of you that think Aluminium is more resistant to impact damage here’s my mates down tube from a few years back: http://mountainbikerides.co.uk/photos/ouch/broken-bikes/rock-strike-2009.html

And here’s a Santa Cruz another mate tested (without the need for them fancy jigs!) too: http://mountainbikerides.co.uk/photos/ouch/broken-bikes/santa-cruz-superlight-vs-tree-1981.html

My calculations are wrong, but the energy required to break the carbon frame from the drop test is equivalent to an average man riding into a paper wall at over 5000mph with no energy dissipation from tyre, air, rims, spokes, hubs, bearings, or forks.

an average man

What about a fat, middle aged, IT professional ?

scuzz – Member

My calculations are probably wrong, but the energy required to break the carbon frame from the drop test is equivalent to an average man riding into a wall at over 7mph with no energy dissipation from tyre, air, rims, spokes, hubs, bearings, or forks.
Posted 3 minutes ago # Report-Post

I am not sure if your calculations are right or wrong but if they were right how fast would you have to be going on the aluminium bike? Less than walking speed? Something sounds amiss.

I am not sure if your calculations are right or wrong but if they were right how fast would you have to be going on the aluminium bike? Less than walking speed? Something sounds amiss.

It’s very amiss, there’s copious amounts of editing going on here – soon it’ll be a post about something completely different. It’s mainly because I’m incompetant.

I view this simply as a materials demonstration.

To this end, the results are not unexpected or even a surprize.

The question that comes to my mind though is this:

Do you want a bend to occur, but for the frame to remain in one piece.
The bend will occur more slowly compared to the instant and catastrophic failure such as that seen with carbon.

Carbon, may yield only at higher stress / load, but when it does fail, its very quick, and results in smaller parts, each with sharp edges, etc.

Personally, while I do have one or two carbon components on a few of my bikes.
I’d mostly always choose Aluminium for its “bending fuse” characteristic.
A slow bend / deformation, in preferrence to an instant and catastrophic failure.

😉

Most aluminium frames I’ve seen bend due to heavy impacts of the sort in this test have bent to the point that whether they’ve actually snapped or not is irrelevant – the rider has crashed because a wheel’s hit the frame or similar.

‘Bending fuse’ is just a marketing term in the real world IMO.

You could hear the carbon strands breaking on the first test at around the same point as the alu frame bent. That would suggest that it might look fine for several impacts but then fail spectacularly.

Also the Alu failure wasn’t what I’d call catastrophic where as the carbon failures didn’t just bend they totally failed. I’d rather have a frame bend and keep going than the front end totally separate.

The carbon frame survived 110lb at 800mm drop which equates to a G.P.E = 441J

A rider of 95 kg (kited out (that’s me) on a 10.9 kg bike would have to travelling at 2.9 m/s to be carring 441J of energy. That’s only 6.5 mph but that assumes no energy dissapation by the tyres, rims, forks and non of the K.E being transfered into rotating the bike which would happen in reality.

That test is simply not real world but it does show the toughness of the material quite well.

I’ve not looked at the post, bu I assume they are trying to pursuade more people to buy more plastics bikes than metal ones because they make more money on them… or is that just a silly way to be looking at it ?

I was in Spain with Switchbacks. My mate was on his 140MM Carbon Mojo. Hit a rock. Hole in frame. My Heckler survived.
Another friend swapped his old Whyte 146 for a Cannondale Mojo recently. He jumps well! Broke the Mojo frame pretty quickly. A lot more of my riding friends ride Alu as opposed to Carbon but a much higher precentage break their carbon frames. (Although I did crack my E5)
I have no doubt you can scientifically prove that carbon is stronger than alu but in the real world in my limited expericnce carbon breaks more than alu. So far you can’t tempt me to buy a carbon frame (Although I have ridden a Whyte 146 and it is an awesome bike)

whether they’ve actually snapped or not is irrelevant

I disagree. I think its very relevant.
As I posted, I’d rather sustain a bent frame from an impact / crash, which in all likelyhood I’ll still be able to ride back to the car.

Rather than have an instant catastrophic break in the frame, which produces sharp edges, which in turn could cause issues for me during the crash with secondary impact, etc.

Yes, I’ve seen Thompson use the term ” Bending fuse ” when describing their products.
What we’re really describing though is the material being strained beyond its elastic limit, resulting in permanent deformation.
And again, Aluminium is going to reach its elestic limit way before steel.
Obviously you will eventually snap a metal too, but only after deformaion has occured and the elastic limit of the material has been exceeded.

I’ve see carbon deform before failure too, but it all happens rather too quickly for my liking.

😉

I enjoyed that.

Really impressive that the first carbon frame had already been through a load of fatigue tests and had been ridden for 2 years. Also slow loading like that is really not favourable for composites and is not that realistic. In real life the impact would be very fast and you get high strain rate effects were the material will actually take a much higher instantaneous force with no or very little damage.

The weight drop test was also very impressive and as for the concrete block – sheesh!

But SC need to take some lessons on PPE! 😀

PS in the weight test the front end didn’t actually fully separate. CF doesnt always explode/fall apart/turn to dust. It can stay together when ‘failed’

FunkyDunc – Member

I’ve not looked at the post, bu I assume

There is your problem right there.

Luminous – Member

whether they’ve actually snapped or not is irrelevant

I disagree. I think its very relevant.
As I posted, I’d rather sustain a bent frame from an impact / crash, which in all likelyhood I’ll still be able to ride back to the car.

Rather than have an instant catastrophic break in the frame, which produces sharp edges, which in turn could cause issues for me during the crash with secondary impact, etc.

Yes, I’ve seen Thompson use the term ” Bending fuse ” when describing their products.
What we’re really describing though is the material being strained beyond its elastic limit, resulting in permanent deformation.
And again, Aluminium is going to reach its elestic limit way before steel.
Obviously you will eventually snap a metal too, but only after deformaion has occured and the elastic limit of the material has been exceeded.

I’ve see carbon deform before failure too, but it all happens rather too quickly for my liking.

If I had been in a crash where the frame has bent I would be pleased to walk back. I would be more concerned about my own well being than the bike and certainly wouldn’t be riding a bent bike aftwerwards.

I also think that the time taken for the failure to propogate is irrelevant. An Alu frame letting go in .5 of second isn’t giving you time to do anything about it just as 0.01 of a second for aa Carbon frame isn’t. I would rather take the extra strength so it is unlikely to happen in the first place.

Carbon fibre can be made as stiff or as bendy as you like.

This is a windsurf mast

Normally it’s a straight 2-piece (ferrule joint in the middle) 4.5 metre tapered pole that has to withstand lots of forces and knocks. If you exert a lot of pressure it will bend like this. And bounce back unharmed. Very quickly – much quicker than aluminium, which is why we all stopped using ally masts, because the fast reflex is important.

They last for years too – unlike ally.

The carbon frame survived 110lb at 800mm drop which equates to a G.P.E = 441J

A rider of 95 kg (kited out (that’s me) on a 10.9 kg bike would have to travelling at 2.9 m/s to be carring 441J of energy.

No it equates to 441N of Force.

Give the length of the Fork of 500mm

That equates to 220Nm or 220J at the head tube.

You point is totally correct, its not that much compared to a 100kg rider hitting something at say 20mph, twice the energy would be involved.

But SC need to take some lessons on PPE

I have to confess that was one of my first thoughts as well….

Death is indeed long, but I’m not convinced it’s painful.

if you die from carbon shard encephalitis then it still hurts even when you’re dead. this is a hard FACT.

If we’re chipping in anecdotes, the only bike I’ve seen wrecked by a rock strike was titanium, dented and cracked the down tube on a gnarr chilterns ride. It’s not just the material its how you use it.

To stevewhyte I think you need to brush up on your Physics. G.P.E is energy and is measured in joules not Newtons. The only way to solve the problem presented by a pevious poster of equivelent crash speed is to use the conservation of energy.

The force imparted to head tube by the weight is dependent on the change in momentum (calulable from the height of fall, gravitational field strength of the earth and the mass) and the impact time (unknown) so it impossible to determine impact force. F = (mv-mu)/t

Hense conseravtion of energy is the only to work anythg out. Working out the force on the head tube does not help you work out the equivelent impact speed.

Also the rider normally comes of in a crash so 441J equates to the bike alone (10.9 kg) travelling at 9 m/s or ~20 mph assuming no energy absorption by the tyres, tube, rims, spokes, hub, forks and the assuming the bike does not rotate. All of which are not ture so you would have to ride into a wall about 25 mph or more to crack that carbon frame upon which cracking the frame is the least of worries.