George Hincapie's stack due to a broken fork steerer. Was it Carbon or Alu? (The steerer that is)
http://www.youtube.com/watch?v=PBzeQQs97YA
http://www.youtube.com/watch?v=PBzeQQs97YA
What broke? Carbon or Alu?
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It was an black anodized aluminium steerer. He used it as it had clearance and dimensions for paris-roubaix. very strange that it should break though. Conditions must be so much worse than we can imagine. Must have fatigued mighty wuickly with the cobbles.
Hincapie is not the sharpest tool in the box. In the days before P-R he and the team tested wheels they intented to use. He was intentionally bashing into potholes trying to break the wheels. Who know what damage he may have done to the steerer. He then had at least one crash in P-R before the failure, and he ignored noises from the bike thinking it was a loose headset.azdroptop said:
If I remember right the fork itself was not one of the high end products from Trek. It was something from their commuter range. This was used because it had a greater rake, improving comfort on the cobbles. There seems to be some confusion over the exact fork model. Trek gave some information that did not match up with post crash pictures.
Ah, that makes sense then...azdroptop said:
I seen a few forks here and there on ebay and online shops and some have alu and some have carbon steerers... Always wondered which is best, but when I saw that vid I thought hmmmmm wonder what material that was...
Even if it wasnt high end it had been reworked by Trek. for example, the aluminum steerer was shot peened (for strength).Bro Deal said:
Having seen a lot of this failures, in my mind this area is the weak-link in an A-Head system. I also think that an aluminum steerer will be prone to this failure more than any other material.
Carbon and aluminum both have vulnerablilities as a steer tube material, but it's pretty ridiculous to blame the steerer - the blame lies in the earlier crash and ignoring the warning signals. It's completely possible for a carbon steerer to fatigue in the same way. It won't happen to you because you wouldn't go pounding over a hundred km of cobbles after a crash and a headset that feels funny.
Whether it's pounding over cobbles or silky smooth roads is not what I am talking about. From experience I have witnessed many cases where the steerer broke just like hincapie's. These were all road bikes during crit races and 1 during a high speed training ride. In all cases the roads were smooth and the steerer just gave way and in all cases the steerer was aluminum and and A-Head set up. I am yet to see this happen with a steel, ti, or carbon steerer. The point is aluminum gives no warning when it snaps specially when using an A-Head set up. This wont happen on a quil system. And yes it has happened to me - an aluminum steerer - not abused and used only on paved roads!!! Again I repeat what I think is the weak link on an A-Head set-up and that is the area on the steerer just below the stem.DiabloScott said:
you can see the full spec here http://www.cyclingnews.com/road/2006/apr06/roubaix06/?id=/tech/2006/features/hincapie_trek
Bro Deal said:
hd reynolds said:
Nope - steerers do not just give out. I don't care what you've seen, it doesn't happen. There was existing damage in every one of those cases, or there was improper installation, or a singular material fault. I don't want to get in a pissing contest with you, but I don't want the readers of this forum to be needlessly frightened of a perfectly good component.
You just reinforced my point - steerers break because they get damaged due to fatigue. The existing damage you say is there is due to fatigue. And more than any material used in the bike industry aluminum is more prone to fatigue (its a no brainer).DiabloScott said:
And improper installation or not - carbon, steel or titanium will not break and cause an accident in that spectacular fashion. Contrary to general belief, after the advent of the A-Head system, it is the steerer that breaks more often than say fork crown or fork legs.
hd reynolds said:
No, and as I've said many times, the BS on this forum about fatigue is astounding.
All fatigue failures start with an incipient crack. Steel, titanium and aluminum will all fatigue in the same way (more or less) once the crack has started. Hincapie's steerer made of any of those materials would have broken in a similar manner. A steel or ti tube may have given a little more warning, that's all and maybe not even that (actually I'm not even aware of any ti steerer forks). A carbon tube probably would have shattered in the earlier crash to begin with - from some observation point I guess you can say that's better.
Do not fear the aluminum steerer! There's no way you'll ever see enough cycles to fatigue one without crash damage.
alfeng said:
OK, I see Alpha-Q had one also - don't appear to make it any more and it doesn't appear to have any advantage over steel or aluminum though, and is more susceptible to fatigue - BUT ONLY AFTER A CRACK STARTS which might be the case after a crash.
Ti steerers are much harder to cut down, that's probably why they're so rare.
Additionally, the titanium steerer option on the Kestrel fork was more than $200US MORE than one of their "regular" carbon fiber forks ... something like $450US, 5+ years ago, comes to mind.DiabloScott said:
FWIW. The only way I know how to "cut" a titanium steerer is with a hand grinder ... there is probably a more elegant way to do it.
Okay, I agree with most of what you say. Especially about not fearing aluminum! I agree that fatigue failures can start with an incipient crack. However, fatigue failures have another known mode. Weak spots inside and inherent to the material such as an inclusion, impurity or other irregularity are known nucleation points for fatigue cracks. The crack grows from that point until it breaks. This is why all metallic structures have a well defined fatigue life.DiabloScott said:
Aluminum can be a bit worse than other materials, but this can be counteracted with good design. Generally, metallic fork steerers should have at least an order of magnitude more fatigue life than your chain stays because of the immense wall thicknesses.
The big question mark is carbon. It's fatigue modes are undefined, since there are no grain irregularities, impurities, etc. And when there are inclusions or voids, the cracks only propogate until the next layer where they stop (isotropic materials do this at boundaries). Carbon fiber hasn't been around long enough for engineers to know what it's typical lifetime is under a known load. It's obviously a long time, but it's undefined right now. At least that's the last I heard on the subject. Experts might disagree.
John Swanson
www.bikephysics.com
I think you’re the one full of BS.DiabloScott said:
Just look at your post, its full of negativity.. And your previous one? Trying to arouse sympathy and get everyone to gang up on whoever disagrees with you? Then you accuse me of trying to scare everyone off aluminum? BS ain't it.
Instead why don’t you open up your narrow mind, read my posts again and really see the wisdom of it. If you cant, let me spell it out for you like a five year old. ----> Any one using an aluminum steerer for sometime should examine theirs to avoid such failures, specially more so if involved in a crash. I am not against using an aluminum steerer.. I've used one for years (till it broke because I didn’t examine it whenever I serviced the headset).
And one more question for you Diablo... Hincapie crashed, and what broke? Yes an aluminum steerer!!!
(he could have broke the carbon legs of his fork or the carbon top tube or the carbon downtube or the carbon chainstay or the carbon ... whatever). 
hd reynolds said:I think you’re the one full of BS.
Just look at your post, its full of negativity.. And your previous one? Trying to arouse sympathy and get everyone to gang up on whoever disagrees with you? Then you accuse me of trying to scare everyone off aluminum? BS ain't it.
Instead why don’t you open up your narrow mind, read my posts again and really see the wisdom of it. If you cant, let me spell it out for you like a five year old. ----> Any one using an aluminum steerer for sometime should examine theirs to avoid such failures, specially more so if involved in a crash. I am not against using an aluminum steerer.. I've used one for years (till it broke because I didn’t examine it whenever I serviced the headset).
And one more question for you Diablo... Hincapie crashed, and what broke? Yes an aluminum steerer!!!
Talk about being full of BS: you've presented zero science or deductive logic, but you have brought a lot of invective. You should take some engineering or science classes, so you can learn some science, reasoning, and empirical thought.
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