Carbon Frames, not always best

[Hawkwood]

I had an experience two weeks ago that will forever make me a fan of carbon fiber frames.

I was descening a hill, going about 30 mph, when a car pulled out of a side road directly blocking me. I had the right of way and no way to stop. I went right into the back quarter panel and was flung over the trunk, landed so as to have my head bounce and came to rest on my hands and knees. By all accounts I ought to have just gotten out of the hospital, but I only spent an afternoon in the ER getting patched up.

My bike a 2006 Trek Madone 5.2 OCLV was destroyed. The steerer tube blew out of the headtube and the deep rim of my carbon wheels blew apart as wheel. The bar (also carbon) was obvioulsy cracked in multiple places under the bar tape. I'm convinced the carbon fiber is what save my skin.

I'm in the camp that the number of crashes this year has more to do with nerves, fatique and poor bike handling than anything else. There did seem to be a higher than normal amount, but I don't think the frame has anything to do with that, unless there was a material failure that would then cause a rider to go down, taking others with them.

As for postion, etc., I'm sure that like someone else pointed out this changes all the time and for each rider it will be different. I personally think the bikes look cooler with the bar & stem "slammed" down. Do I have my bike set up that way? No, but I still liked the set-up I had, because it fit and worked for me.

As for the OP, it does seem, while an interesting discussion has arisen, that they were trolling to some extent. I might have missed it, but it appears they have not responded since the post.

Sorry to hear of your crash, but pleased to hear that you have no serious injuries. I'm interested that you think the carbon-fibre frame saved you, why is this?

I should point out that 'm not anti carbon, in fact I'm keen on buying a carbon frame next time round. The roads in my area are so bad I'm interested in seeing if carbon will dampen the vibrations.

I like the slammed stem look as well, but on my current frame that would give me a saddle/bar drop of about 10 cms, okay for a pro, but not me. I think the issue might be about sizing, I'm 6ft 1in tall and am riding an XL or 61 cm frame. My experience is that on large frames the head-tubes aren't scaled up proportional to the frame size, hence the problems I've had even getting a frame that would give me as `little' as a 10cm drop. I first noticed the problem when I switched from a 1997 Bianchi with typical racing geometry of the time to a 2006 frame with `modern' geometry. I couldn't understand why I couldn't get a good position on the latter, until I got the tape-measure out and realised the head-tube length was completely different.

 

[cawright1375]

The reason I think the carbon saved me from a hospital stay was that it absorbed the impact of the crash. Carbon is known for absorbing road vibration and I agree to that based on my experience. I think a steel or titanium frame would not have absorbed the impact as well and that perhaps more of that energy would have been transferred to me.

I'm no physicist or engineer but that is what I think based on what happened. There is just no other way to explain it.

And yeah, I had a carbon frame, wheels, seatpost, saddle and cockpit and I experienced very little road vibration unless on terrible roads, which in New England are easy to find.

 

[Damiano Machiavelli]

The reason I think the carbon saved me from a hospital stay was that it absorbed the impact of the crash...I think a steel or titanium frame would not have absorbed the impact as well and that perhaps more of that energy would have been transferred to me.

I'm no physicist or engineer but that is what I think based on what happened. There is just no other way to explain it.

I hope you are not serious. This is laughable.

 

[richwagmn]

I hope you are not serious. This is laughable.

And your qualifications are....

 

[Damiano Machiavelli]

And your qualifications are....

Common sense.

 

[stephens]

Huh? The concept he is describing - the vehicle compressing and absorbing energy instead of transmitting it solidly to the rider- is the basis for the way automobiles are designed to act in a crash, the way helmets are supposed to act, and so on.

 

[Damiano Machiavelli]

Huh? The concept he is describing - the vehicle compressing and absorbing energy instead of transmitting it solidly to the rider- is the basis for the way automobiles are designed to act in a crash, the way helmets are supposed to act, and so on.

You do not sit inside your bicycle, secured relative to the outer parts of the bike. A bike does not deform around the rider in a crash and only impart crash energy to the rider once the frame and components can no longer absorb any more. The rider is barely connected to his bicycle.

And furthermore, the idea that the magic of carbon somehow produced a different result than metal is also laughable. Once carbon snaps, it cannot absorb any more energy. Metal will continue to deform, absorbing energy. The one component that might absorb a little energy before the rider becomes independent of the bike is the wheels, and there the metal spokes would be the chief energy absorber. But in order for that to work the rider would have to maintain a mostly rigid position relative to the initial position of the wheels, something I am skeptical that can be done by a rider with a mass of 80 or so kilograms travelling at a velocity of 50 kph. The energy is too great to maintain position with just the rider's hands braced against the bars. Instead the most likely outcome is the rider will be sheered off his bike as the bike is destroyed underneath him. He will travel on to suffer the full impact result no matter what happens to his bicycle.

 

[bc_hills]

You do not sit inside your bicycle, secured relative to the outer parts of the bike. A bike does not deform around the rider in a crash and only impart crash energy to the rider once the frame and components can no longer absorb any more. The rider is barely connected to his bicycle.

+1 on this.

I too failed to understand how cf saved the dude's skin. By his own account he was thrown over the trunk of the car. What saved his skin was hitting a car instead of a bus!

 

[cawright1375]

Well all I can say is that while it might be laughable to you, it isn't too me.

12 stitches, a broken fingertip, bruising, stiff knees and some minor road rash were the injuries I sustained AFTER hitting a car at 30 mph. The car suffered no major damage and yes I was thrown clear.

The carbon absorbed the force of the impact. 'Nuff said.

The bike shop mechanics agreed with me on this. The adjuster and everyone that has seen the bike is amazed I'm not still in the hospital.

This comes down to experience. Have you ever had a car pull out in front of you while you were descending a hill at ~30mph? No, then I don't see how you can say it wasn't a result of the frame and other components.

The bike absorbed the force of the impact and the front of it blew apart as a result. A crack runs down the top tube so don't tell me the force stopped when the head tube blew open.

A steel bike might have done more damage to the car and flung me harder.

Regardless the armchair crash experts will say what they will. All I know is what I know first hand.

 

[kuoirad]

Well all I can say is that while it might be laughable to you, it isn't too me.

12 stitches, a broken fingertip, bruising, stiff knees and some minor road rash were the injuries I sustained AFTER hitting a car at 30 mph. The car suffered no major damage and yes I was thrown clear.

The carbon absorbed the force of the impact. 'Nuff said.

The bike shop mechanics agreed with me on this. The adjuster and everyone that has seen the bike is amazed I'm not still in the hospital.

This comes down to experience. Have you ever had a car pull out in front of you while you were descending a hill at ~30mph? No, then I don't see how you can say it wasn't a result of the frame and other components.

The bike absorbed the force of the impact and the front of it blew apart as a result. A crack runs down the top tube so don't tell me the force stopped when the head tube blew open.

A steel bike might have done more damage to the car and flung me harder.

Regardless the armchair crash experts will say what they will. All I know is what I know first hand.

All that, then let's remember this other little thing you said a few posts ago:

I'm no physicist or engineer but that is what I think based on what happened.

How are you not a "armchair crash expert" then too?

 

[blutto]

You do not sit inside your bicycle, secured relative to the outer parts of the bike. A bike does not deform around the rider in a crash and only impart crash energy to the rider once the frame and components can no longer absorb any more. The rider is barely connected to his bicycle.

And furthermore, the idea that the magic of carbon somehow produced a different result than metal is also laughable. Once carbon snaps, it cannot absorb any more energy. Metal will continue to deform, absorbing energy. The one component that might absorb a little energy before the rider becomes independent of the bike is the wheels, and there the metal spokes would be the chief energy absorber. But in order for that to work the rider would have to maintain a mostly rigid position relative to the initial position of the wheels, something I am skeptical that can be done by a rider with a mass of 80 or so kilograms travelling at a velocity of 50 kph. The energy is too great to maintain position with just the rider's hands braced against the bars. Instead the most likely outcome is the rider will be sheered off his bike as the bike is destroyed underneath him. He will travel on to suffer the full impact result no matter what happens to his bicycle.

...while it is difficult to comment about the specifics of said crash I would have to heartily agree with the above post...modern materials such as carbon fibre and aluminium are prone to catastrophic failure, that is, they shatter, and once shattered they will, as pointed out, offer no shock absorption...

...having been around racing for over 3 decades I've seen more crashes then I care to remember but I really don't remember seeing many steel frames broken into pieces, twisted into really grotesque shapes maybe, but not blown to bits as a modern frame( or wheel ) does...and to the crashee, be thankful that a broken carbon tube didn't penetrate your body ( that I have seen, and it was not very pretty...the carbon edges can be as sharp as a razor and jagged to boot )

...and by the way, I have been the victim of a crash similar to that described in this thread....the bike was a write-off and I slid across the trunk, the roof, the hood and landed on the road in front of the car...thankfully the injuries were confined to some bruises and and a very badly damaged ego...and I have been around several similar crashes where the rider faired very badly...so its hard to draw hard and fast conclusions from one incident that cover all the outcomes that such an accident would produce ( for instance in one such incident a rider went thru the rear window of a hatchback and ended up sitting upright in the rear seat with minimal body damage but a destroyed bike )...

...so...bottom line...if I were to have a choice on what to crash on...it would definitely be steel or Ti ( these materials make good reliable springs, carbon and aluminum do not)...

Cheers

blutto

 

[bc_hills]

Well all I can say is that while it might be laughable to you, it isn't too me.

12 stitches, a broken fingertip, bruising, stiff knees and some minor road rash were the injuries I sustained AFTER hitting a car at 30 mph. The car suffered no major damage and yes I was thrown clear.

The carbon absorbed the force of the impact. 'Nuff said.

The bike shop mechanics agreed with me on this. The adjuster and everyone that has seen the bike is amazed I'm not still in the hospital.

This comes down to experience. Have you ever had a car pull out in front of you while you were descending a hill at ~30mph? No, then I don't see how you can say it wasn't a result of the frame and other components.

The bike absorbed the force of the impact and the front of it blew apart as a result. A crack runs down the top tube so don't tell me the force stopped when the head tube blew open.

A steel bike might have done more damage to the car and flung me harder.

Regardless the armchair crash experts will say what they will. All I know is what I know first hand.

Nobody's laughing at your terrible accident.

Your bike didn't fling you. You and your bike were moving at the same speed and suddenly your bike stopped. Neither your bike nor anyone else's bike will provide any margin of safety in a collision. You say "nuff said" as if your having been in an accident means everyone else should just shut the **** up and not question what you're calling a fact. Do you think someone should feel safer on a cf bike? That's what it sounds like your saying and that's what DM is calling laughable, and it is laughable. If you wanna feel safer and actually be safer, strap on some body armour. Ask any dh rider how much importance they put on their bike frames to protect them in a crash.

 

[JayKosta]

...
How are you not a "armchair crash expert" then too?

===============

uh????
Because he has actual experience doing it.
Maybe he is not a true expert, but he is a 'doer'.
----
Also it seems that some pro riders prefer aluminum bars & stem to carbon because they can feel more flex with carbon.
The flex with carbon bars would absorb some energy in a crash.

Jay Kosta
Endwell NY USA

 

[cawright1375]

All that, then let's remember this other little thing you said a few posts ago:



How are you not a "armchair crash expert" then too?

Because any armchair expert, whether it be football, basketball, baseball, or cycling is someone that doesn't participate in said activity. Furthermore because I know I have to clarify this, there is also a difference between racing, riding and cruising around on a bicycle. I survived my crash and again everyone from the insurance adjuster, to the shop mechanics to every concieveable type of bike shop customer are amazed that I survived the crash without spending more than an afternoon in the ER. So am I an expert on every crash ever - No. I am an expert on mine and the shop mechanics who had no reason to agree with me, agreed that the frame material saved my ****. And to further clarify, they agreed with me knowing full well I wasn't buying from their shop or the brand they carry. So it wasn't like they were inflating my opinion for their benefit.

And yeah I get that whomever it was that said my opinion is laughable was not laughing at my accident. He thought my opinion was laughable, I get that. And while my high school phsyics class was close to 20 years ago I also understand that my bike stopped moving and I kept going. However, I was flung over a car and onto the ground, the EMTS and cops said I should have been hurt worse. So unless I suddenly became the main character in Unbreakable, something happened to absorb some of the force of the impact....

Oh wait - it must've been the religious medals I have attached to my helmet straps (St. Christopher & Madonna del Ghiasallo) that miraculously enshrouded me in a protective cocoon.

 

[cawright1375]

, agreed that the frame material saved my ****. And to further clarify

Huh that is weird, the word that is x'd out, isn't what one would consider a bad word that needs censoring. In fact the word that was used, just had an extra 't' on it. I wonder what other common words that one wouldn't find offensive are blocked. I suppose that is a whole other topic!

 

[kuoirad]

And yeah I get that whomever it was that said my opinion is laughable was not laughing at my accident. He thought my opinion was laughable, I get that. And while my high school phsyics class was close to 20 years ago I also understand that my bike stopped moving and I kept going. However, I was flung over a car and onto the ground, the EMTS and cops said I should have been hurt worse. So unless I suddenly became the main character in Unbreakable, something happened to absorb some of the force of the impact....

That's the thing - by your account, you didn't impact the car. Your bike did. You were flung *over* the car. The bike had absolutely no influence on the force of your impact with whatever you hit - I'm assuming the ground.

How did you fall? Your position when you hit the ground will have a large effect on the forces applied to your body. If you fell flat onto your back, the force of impact got spread over a much larger area than if you'd fallen forward onto your outstretched hands/arms - and you'd likely come out of it with lesser injuries. It's basic physics.

You're making assertions about carbon fiber and it's role in the physical outcome of your crash that don't pass Occam's Razor, much less basic physics.

 

[ksmith]

So lets see, your saying your bike is a deformable structure that saved your life even though a fraction of a second after hitting the car the bike stopped and you continued. I am a little confused how the energy absorbtion of your bike slowed your movement as you were a loose projectile.

If the power absorbtion of the bike was that great I'm sure Trek would be flogging it in adverts. Also please ask your mechanic the crash data on ANY bike, I am certain we would all like to reduce our injuries.

I to am recovering from a tagging namely a hit and run last August so I know about crashes as well.

It had nothing to do with the crushability of my bike. It was my lucky day, just as I think it was yours. Anyway, good luck with your injuries. As the old saying goes it could've been worse

 

[Hawkwood]

I'm no expert, but isn't this why in a crash you're better off in a car than on a bike or motorbike? In a car you've got crumple zones, air-bags, reinforced panels, and seatbelts. The car is designed to absorb the energy while cushioning the occupants. However the issues with a bike or motorbike are that there are no crumple zones and other safety features, you simply get thrown from them as in this case.

As for carbon versus steel, I have seen several steel frames that have been in crashes and the classic damage was forks bent back, and crumpling on the down-tube, I assume these are classic signs of the frame absorbing energy.

 

[ksmith]

I'm no expert, but isn't this why in a crash you're better off in a car than on a bike or motorbike? In a car you've got crumple zones, air-bags, reinforced panels, and seatbelts. The car is designed to absorb the energy while cushioning the occupants. However the issues with a bike or motorbike are that there are no crumple zones and other safety features, you simply get thrown from them as in this case.

As for carbon versus steel, I have seen several steel frames that have been in crashes and the classic damage was forks bent back, and crumpling on the down-tube, I assume these are classic signs of the frame absorbing energy.

Bent fork, crumpling forks are energy absorbtion signs, the rider meanwhile is flying like a kamikaze pilot off the bike.

You should be strapped in the car (seatbelt) for the crumple zones to work coorrectly, if you are not, you are a loose projectile just like on a bike.

This disscussion is about the crumpling of a bike frame saving a person from worse injuries than received, not if a bike frame crumples.

 

[blutto]

I am watching the TDF: Specialized, Trek, Pinnarello..etc, your bikes are worthless at high speeds during descents or in the peloton when control is important. It's time to go back to the drawing board!

...find below an article about some changes in the way certain modern bikes are evolving...in this case using rider feedback to change a design direction that seemed to be somewhat divorced from cycling reality ( maybe one that was a bit too engineer driven and that neatly translated into a more is better advert blitz )...the end result is a bike that probably handles better because the changes allow for better control...

http://velonews.competitor.com/2011...s-of-htc-highroad-saxo-bank-and-astana_186391

Cheers

blutto

 

[Hawkwood]

Bent fork, crumpling forks are energy absorbtion signs, the rider meanwhile is flying like a kamikaze pilot off the bike.

You should be strapped in the car (seatbelt) for the crumple zones to work coorrectly, if you are not, you are a loose projectile just like on a bike.

This disscussion is about the crumpling of a bike frame saving a person from worse injuries than received, not if a bike frame crumples.

I know, I agree with your post. I wanted to make the point that if we really throught a bike was going to save you then steel appears to be a good absorber of energy. I think that in this case a combination of luck, the angle of the collision, and the way the rider fell played the major part in him escaping with minor injuries. I was in a road race in the 1980s where a mate crashed into the back of a parked car on a descent. The bike was a write-off, the back of the car had expensive damage, and my mate? Well he flew off his bike, straight through the glass window of the rear of the car, and landed unharmed on the back seat! I'm guessing that only small differences in speed, angle of collision, plus the type of car would have resulted in him being seriously injured or dead. He always was a lucky b*st*rd, you should have seen his girlfriend!