Carbon Fragility

benhben

I know the topic of Carbon in a crash has probably been done to death. However, i recently bought a great Moda Stretto bike. Two weeks after getting the bike I had a crash involving a car that drove right accross me. Not a massive crash but I went over the handlebars trying to stop and both me and the bike hit the floor. The bike was written off as unsafe due to a slight mis-alignment of one of the rear forks. A non-carbon bike would have been easily ridable, but due to carbons nature of failing suddenly without warning due to internal damage I will have to replace.

This has got me thinking, when I replace the bike, is the fragility of Carbon worth the advantages it brings. When Aluminium bikes such as the Cannondale Caad 10 get excellent reviews, and may prove more durable than a carbon alternative, whats the reason for going carbon?

In this case the driver was at fault and I will be getting a payout via his insurance. But not every crash I have will be someone elses fault. Am I going to have to worry about breaking a carbon bike every time I come off it?

jgsi

well , I better re assess then in light of this... had a bit of an off in a final straight bunch sprint and ended up on my arse havin sat on the back end of my bike and writing off the rim... big style
The frame was skewed..more than likely due to the alu shimming in the carbon seatpost. after due deliberation and not wanting to lose 2k s worth of frame, I give it a big big tug on the jig and lo !.. the spare wheel fit again...
One careful going over the entire frame.. nowt wrong with it.
Carbon will break/snap when its had enough..but it's a tough old material.. I would not describe in any way
as fragile
until then I'm happy to ride it and race it.


I'd get that frame back if I were you...

benhben

Once the claim is sorted, aslong as I still have the bike Ill take it for a 2nd opinion damage assessment. I know for insurance claims that any carbon bike involved in an accident is written off, but the bike mechanic indicated he wouldnt feel confident riding my frame with the impact the back of the bike had.

The bike didnt even take a massive impact, I took the brunt of it.

TheEnglishman

If the insurance is paying for a new bike why are you worried about salvaging a crash damaged frame? Bin it and enjoy the fact you can still ride anything!

benhben

TheEnglishman wrote:

If the insurance is paying for a new bike why are you worried about salvaging a crash damaged frame? Bin it and enjoy the fact you can still ride anything!

Thats the whole point. One crash in which the bike didnt even take much impact has written off a £2000 carbon frame. Is it worth replacing with another carbon, or will that be written off on my next fall.

I understand the performance benefits, just seems quite a fragile material.

jgsi

TheEnglishman wrote:

If the insurance is paying for a new bike why are you worried about salvaging a crash damaged frame? Bin it and enjoy the fact you can still ride anything!

No, read back, its not the OP wanting to salvage, it's me ..

whats the frame then?
If you can post a pic of the state it is in

Tom Dean

benhben wrote:

carbons nature of failing suddenly without warning due to internal damage

Is irrelevant since your frame was visibly broken. Would you have carried on riding on an Al frame with bent stays and forgotten about it?

nochekmate

But don't bin the frame - sell it as damaged. There are plenty of people around who will take on a damaged carbon frame and have it repaired - their choice of course. You may be surprised by how much it fetches!

fungus_the_muffin_man

Its a small bike in a collision with a big car. Of course it came off worse. If you were in your car and you hit another one causing it to be wrote off would you want to get a car not made from same material? Of course not!

Carbon is pretty strong it will only fail following stresses it was never meant to take. As long as you don't crash the new one it should never suffer from a catastrophic failure. So why worry? Just get that lovely carbon bike you've always loved .

MichaelW

How can a crash cause misalignment of a carbon rear triangle? You cannot deform or permanently bend carbon fibre composites. The may bend a little but spring back. Bend them further and they snap.
Was the frame misaligned from new? Aligning most frames at the factory involves hitting them with a big hammer till they look straight. Carbon frames come aligned out of the mould or jig with no corrections possible.

nferrar

Yeah I'm surprised it's 'bent' rather than failed, as above I'd have thought it would just spring back on a minor impact. I wouldn't ride an alu frame after a bit crash if it was bent and I was getting an insurance pay out either. Buy a bike for how it rides not how it stands up to being hit by a car...

kleinstroker

I actually bought a damaged Stretto a while back and am waiting to send off for repairs. From what I've read from F1 engineers and repairers is that most carbon repairs will result in a much stronger frame than original, as the nature of carbon frames is very different from steel or aluminium. Composite technology and performance like the carbon used in cycle frames is not as easy to understand as the the simple fatigue nature of traditional materials like steel and alu, so it's worth asking the guys at Carbonology etc what they think. I for one, certainly will not be worried about riding a repaired carbon frame.

benhben

To look at the bike there would be no visible signs of major damage apart from ripped bar tape and a couple of chips out of the frame paint work. There are no visible bent carbon parts.

During the damage assessment apparently they have a super accurate measuring device which measured a noticable difference in position between both the rear forks. To look at you would never know. He was surprised as he said the carbon frame seems to have acted like an alloy.

What im unconvinced about is, has the frame actually been damaged or was it like that from manufacture and would be fine to ride for the next 10 years.

Once the legal side is all settled and if the Insurance company have not claimed the bike for themselves I will take it for a second opinion.

desweller

Aluminium racing frames are no stronger. The wall sections on those are coke can thicknesses. If you tap them in the wrong way then they're scrap. Just ask Willhub about his CAAD10.

It does sound as though your frame was misaligned from day 1; if there's no delamination or cracking of paint or topcoat then I wouldn't expect the composite to have been damaged.

cougie

I think the frame was misaligned to begin with - so your plan of a second opinion could be right.

And I remember a mates 753 frame - he could dent the top tube in (and out) with his thumb. Perfectly strong enough for racing- just dont smash it side on.

Bar Shaker

Carbon cannot be permanently bent after manufacture. I do not believe the jig test was done accurately.

Tom Dean

So from reading your other thread can we take it that the rear wheel is out of true by 2mm and the frame is not damaged at all?

ballspondroad

Could the misalignment be caused by bent drop outs ? These are usually alloy rather than carbon so might have bent.

jgsi

ballspondroad wrote:

Could the misalignment be caused by bent drop outs ? These are usually alloy rather than carbon so might have bent.

I did mention my frame was twisted cos of a seat post shim.....
if you are chucking the frame, can I have it..? if its a 56 or over , ta

rpd_steve

if you decide your done with it, send me pics and I may well buy it! I will stick it in the carbon dept and build a winter bike! lol But seriously, if you want rid of it or a repair then PM me.

benhben

Once all the legals are completed and the second opinion damage assessment has been completed I will make a decision. I may well just buy a replacement frame and get the LBS to strip all the components off the supposedly damaged frame and add to a new one. Be cheaper than a full bike replacement.

The bike may well be fine but following the damage assessment as has been mentioned in other threads, if you loose the confidence in a frame you will never push it to the max.

The Stretto is a brilliant bike though. Love the American Classic 420 Aero 3 wheelset.

Tom Dean

benhben wrote:

Originally thinking the frame was damaged causing the wobble, turns out its the wheel.

When I say slightly, I mean slightly. To look at you would not notice any damage, however when the wheel is spun and observed closely in relation to the brake pad position there is a wobble of about 1-2mm.

:roll:

giant_man

benhben wrote:

I know the topic of Carbon in a crash has probably been done to death. However, i recently bought a great Moda Stretto bike. Two weeks after getting the bike I had a crash involving a car that drove right accross me. Not a massive crash but I went over the handlebars trying to stop and both me and the bike hit the floor. The bike was written off as unsafe due to a slight mis-alignment of one of the rear forks. A non-carbon bike would have been easily ridable, but due to carbons nature of failing suddenly without warning due to internal damage I will have to replace.

This has got me thinking, when I replace the bike, is the fragility of Carbon worth the advantages it brings. When Aluminium bikes such as the Cannondale Caad 10 get excellent reviews, and may prove more durable than a carbon alternative, whats the reason for going carbon?

In this case the driver was at fault and I will be getting a payout via his insurance. But not every crash I have will be someone elses fault. Am I going to have to worry about breaking a carbon bike every time I come off it?

oh dear! .... answer don't come off it!!

benhben

I have had a second opinion now on the damaged stretto. The left hand dropout (connects the wheel to the frame) is definately slightly mis-aligned. Were talking milimetres. Everyone seems slightly confused as to how a carbon part has effectively bent slightly without any sign of cracking.

I am still debating whether the misalignment is so small that the frame would still be safe but if I do buy a replacement ill try and sell the old frame.

Do damaged carbon frames sell well on ebay/here?

Zoomer37

benhben wrote:

Do damaged carbon frames sell well on ebay/here?

Never seen a damaged carbon frame for sale on here, but I doubt it would get much interest. Thats becuase most on here think that after a crash with a carbon frame the devil then lives inside it just waiting to burst out and turn the bike into a cloud of dust whilst doing 50mph downhill.

desweller

The problem you have with composites is they don't really do plastic deformation. So if the frame has moved then chances are that something has cracked or delaminated.

rpd_steve

DesWeller wrote:

The problem you have with composites is they don't really do plastic deformation. So if the frame has moved then chances are that something has cracked or delaminated.

+10000
This. If it has moved, there IS damage. The epoxy matrix reaches its UTS and fails before the fibers have strained anywhere near 65% of their yield point. Unless of course the frame was never correctly aligned when it cam out of the mold in the first place, and because it was minor you didn't know - we don't tend to check new things too closely!

WheelieBad

I'm new to road bikes but I've looking around trying to find my first bike. At my budget (£1000) there are carbon fiber bikes that are available, but threads like these make me worry about the quality of them. Is it wiser to avoid the lower costing CF frames and stick to the aluminium ones?

rubyrider

WheelieBad wrote:

I'm new to road bikes but I've looking around trying to find my first bike. At my budget (£1000) there are carbon fiber bikes that are available, but threads like these make me worry about the quality of them. Is it wiser to avoid the lower costing CF frames and stick to the aluminium ones?

I have just purchased my first road bike from eBay and it's carbon. It was less than £1000, didn't meet it's reserve but they still made the deal. It was a risk, but I am overjoyed with it. It's pristine. Barely a mark on it. I'm hoping not to crash it!

Some of the manufacturers offer the same carbon frame but with different components, which raises or lowers the price. Maybe you could upgrade components later WheelieBad?

Monty Dog

http://www.youtube.com/watch?v=Y_O9PLorYPA

Try this with an alloy, or even steel frame and tell me which material is more durable?
The problem is that it takes specialist techniques to determine whether a carbon composite has been compromised - shops take the easy way out because they're only interested in shifting product. Like as others have said, you can't 'bend' a carbon frame.

WheelieBad

rubyrider wrote:

WheelieBad wrote:

I'm new to road bikes but I've looking around trying to find my first bike. At my budget (£1000) there are carbon fiber bikes that are available, but threads like these make me worry about the quality of them. Is it wiser to avoid the lower costing CF frames and stick to the aluminium ones?

I have just purchased my first road bike from eBay and it's carbon. It was less than £1000, didn't meet it's reserve but they still made the deal. It was a risk, but I am overjoyed with it. It's pristine. Barely a mark on it. I'm hoping not to crash it!

Some of the manufacturers offer the same carbon frame but with different components, which raises or lowers the price. Maybe you could upgrade components later WheelieBad?

Yeah, I'm sure there are plenty of good deals going around on ebay but I just know my luck and I don't trust myself to be able to see a good deal in terms of it's previous usage.

Yeah I'm expecting to upgrade components once I get a decent framed bike. That being said, I'm still want to be able to ride the thing straight away. Looking at the aluminium frames, the quality of the frames increase most of the time with the price and I'm sure that's the case with CF too. But are the cheapest CF frames better quality than the aluminium ones?

But I'm sure the cheaper frames would be made from less quality CF(if that's possible?) so would that make