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Discussion Starter · #1 · (Edited)
Here's the snap shot from cyclingnews.com

I'm still wondering what's Trek has to say about this?

Photo removed in violation of copy right. sorry
 

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I know there's been 3958 posts about this already but I'll reply anyhow.

If it weren't for the first crash early in the race I'd be more concerned about the quality of that particular component. Not about Trek components in general though. Discovery's (Postal) been racing these bikes for a long time with no trouble. It just makes sense that the first crash cracked or weakened that part. Trouble is that if it was cracked, there was really no way of knowing without taking it apart. In hindsight they shoulda changed out to the spare bike after the first crash. I'm sure that'll become standard practice now though.

Just my 2cents.
 

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well that pic confirms it was Alu

so if they anodized the steerer (which should protect it a bit from various impacts) WTF
caused it to fail?
you have to have some sort of issue with the metal to cause it to snap as such.maybe a unseen microcrack that expanded with ther abuse.
 

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Anodizing is just a coloring process. Neither good nor bad for strength. Shot peening is for increased strength. It helps to stop any microstresses from estrusion or machining.
Looking at the height of the the break I stand by my first diagnosis. The King top race is missing and would have been higher than the break. The first crash probably cracked the steerer and loosened the headet. Riding on cobbles for the next few hours would have caused the King race, which is a tight fitting piece to rock back and forward stressing the area where it appears to have broken, leverage on the stem finished the process. 140mm is long but I bet a 120 or 110 stem would have done the same. It is not any manufacturer's fault. Simply the culmination of many unfortunate smaller problems that led to the end.
 

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Anodizing

besides adding color has a hardening effect on the surface. it only goes as deep as the process but it makes things a tad harder but a tad more brittle (again just at anodizing depth). there is no other reason to anodize something that isn't seen except through the gaps of the stem. I don't think they'd go to such lengths for a microscopic level cosmetic effect especiually since LA won 7 TdF's with silver showing through. There has to be a reason for the process besides 'adding color'.
 

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Howzitbroke said:
Anodizing is just a coloring process. Neither good nor bad for strength.
Anodizing basically creates an oxide layer (mostly corundum) of order 10 microns thick. Since the oxide is a lot harder than metallic aluminum (9 versus 2.75 on the Mohs scale), anodizing significantly reduces wear when a part is subject to friction. It also helps the cosmetics because anodized parts resist getting scratched up.

I'd guess that they want to anodize the steering tube not to protect against breaking but to reduce wear from contact with the headset bearings.
 

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Steerer tube does not touch any bearings. The upper and lower race, coppression or star nut, and the spacers and stem. (in the case of an aheadset.) The lower race gets pounded into place on a machined shoulder at the fork crown steerer junction. the top race is held stable by the stem and a compression ring of some sort. With King there is a one piece race compression ring, Most manufacturers use a 2 piece race/compression thingy.
 

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Friction_Shifter said:
long stem didn't help matters. Maybe it failed in tension? I dunno, pure speculation.
Oh my god, you mean these bikes can't handle the cobblestones and crashes and are subject to stress failure?! :eek: God forbid!
 

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Beveled crack?

Is it me or does the break in GH's steer tube look beveled? I dunno.
 

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jaded bitter joy crusher
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Howzitbroke said:
Steerer tube does not touch any bearings. The upper and lower race, coppression or star nut, and the spacers and stem. (in the case of an aheadset.) The lower race gets pounded into place on a machined shoulder at the fork crown steerer junction. the top race is held stable by the stem and a compression ring of some sort. With King there is a one piece race compression ring, Most manufacturers use a 2 piece race/compression thingy.
Of course you're right. Thanks for the correction. In this case, the anodization is probably to prevent galling by the stem and the place where it fits through the upper headset cap.
 

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not broken?

Question:
Is it possible that the steerer is not broken?
It looks like that could have been the top of the steerer where it was cut(with a pipe cutter, that would explain the rather clean bevel) and the fork has slid down and there is exposed steerer below the lower h/s cup? His stem bolts could have rattled loose and while trying to steer his stem slid up.
Just a thought.
 

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Discussion Starter · #14 ·
jkrocket said:
Question:
Is it possible that the steerer is not broken?
It looks like that could have been the top of the steerer where it was cut(with a pipe cutter, that would explain the rather clean bevel) and the fork has slid down and there is exposed steerer below the lower h/s cup? His stem bolts could have rattled loose and while trying to steer his stem slid up.
Just a thought.
That is one crappy pipe cutter. In my eyes that's not a clean bevel. There's another shot where the cap is still in place, I can't find it but it's out there somewhere.
 

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Discussion Starter · #15 ·
jkrocket said:
Question:
Is it possible that the steerer is not broken?
It looks like that could have been the top of the steerer where it was cut(with a pipe cutter, that would explain the rather clean bevel) and the fork has slid down and there is exposed steerer below the lower h/s cup? His stem bolts could have rattled loose and while trying to steer his stem slid up.
Just a thought.
Here's the picture w/ the cap still on.
 

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Pipe cutter,, hmmm,, hadnt thought of that.. I smell a conspiracy theory here.. I wondered why that domestique on CSC was wearing leather work gloves.
 

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Headset cap

If the headset cap had a larger diameter by even the slightest bit it could have stayed snug enough to stay in for a minute. It could have also kept the stem from clamping with all its force on the steerer if some of the force was holding the cap instead.
 

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Just a thought: If I remember correctly GH didn't have any spacers on his steer-tube, right? My thought is that the constant force of weight being applied to the bars from the jolts/bumps in the road (cobbles) would cause a leverage type force on the steer-tube. With no spacers, this would concentrate this force to the area of steer-tube between the bottom of the stem and the top of the head-set, which is minimal in this case. If the steer-tube was longer, then this force would have been spread over a larger area. Someone please correct me if I'm wrong.
 
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