Trek Madone carbon steerer tube failure
05-31-10, 05:31 PM
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Really? So one stem design can break a carbon steerer but all others are safe? Not exactly confidence inspiring.
05-31-10, 08:10 PM
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Local amateur squad in the Northeast had that issue - 2-3 bikes had steerer failures at Battenkill. They were overnighted alloy steer tubed forks the next day.
06-01-10, 06:48 AM
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UPDATED: Service Information - Stems on Carbon Steerers
05/24/2010
Updated installation procedures for stems on carbon steerers
Modern bicycles use high-tech materials and designs that rely on correct maintenance, precision workmanship, and compatibility of the parts. Mechanics must continue to learn the new procedures and requirements of these new bicycles. Incorrect mechanical work on a bicycle could lead to damage or breakage of a part, which could lead to a crash.
This bulletin includes information from an August 2009 Bontrager service bulletin, the Trek and Fisher bicycle owner’s manuals, 2010 Madone and Cronus assembly manuals, and new information.
Below the stem on all steerers
Always place at least one 5mm spacer below the stem. This spacer is in addition to the bearing cover, which must be at least 5mm. If the stem rests against the bearing cover, a point load is created on the steerer that could eventually cause the steerer to break.
Above the stem on carbon fiber steerers
With a carbon steerer, always place at least one 5mm spacer above the stem. A stem placed right at the top of the steerer can put too much force on the unsupported cut edge of the steerer, possibly crushing the steerer.
Check headset bearing preload
The bicycle owner’s manual tells a rider to check the bearing adjustment of the headset each month. With a carbon steerer, a rider should check more frequently. In addition to the checks in the owner’s manual, we recommend an additional quick check: the rider should check to make sure that the spacer(s) below the stem cannot be rotated with the fingers.
Tightening clamp bolts
When tightening clamp bolts on a carbon steerer or other carbon part, make sure to locate proper torque on the part or in the part’s manual and set the torque wrench correctly. Gradually tighten each steerer clamp bolt, alternating back and forth in small increments, until both bolts are at the correct torque. Use a similar method wherever there are multiple clamp bolts. Do not tighten one all the way before tightening the other, and do not leave the bolts with unequal torque.
Compatibility with all steerers
Make sure the stem clamp is designed correctly and is free of burrs. Correct design requires that the clamp is circumferential (closes in a circle); never use a wedge-type clamp. Also make sure the clamp bolts are tangential to the steerer. Angled clamp bolts can cause a point load along the clamp.
Clamp edges should be smooth and slightly rounded. If a stem has a sharp or burred edge, sliding it onto the steerer could scratch or cut the carbon fibers, which can weaken the steerer..
Compatibility with carbon steerers
With a carbon steerer, do not use a star-fangled nut; use only the compression nut assembly supplied with the fork. A star-fangled nut can scratch or cut carbon fibers, which can weaken the steerer.
With a carbon steerer, never use a stem with cutaways or holes in the back of the steerer clamp because this type of clamp can cause uneven pressure on the steerer. Uneven pressure, also called a point load, can damage the steerer. For contrast, the stem in Figure 5 (see PDF) does not have a cutaway.
With a carbon steerer, never use a stem with clamp bolts that require more than 55 lb•in (6 Nm) torque. Excessive torque can crush a carbon steerer.
Use a stem with a carbon-friendly design. The steerer clamp should have the maximum possible surface area and apply even pressure (it should not cause a point load). One cause of point loading is a cutaway in the stem, either in the back as mentioned above, or in a misplaced “lightening hole”. If the lightening hole is too close to the top or bottom of the stem, the narrow, remaining clamp area can cause a point load. To distribute the pressure evenly, the lightening hole should be at least 10mm from the top or the bottom of the stem. If a misplaced lightening hole is combined with incorrect spacers, the stem can crush the steerer. FSA stems are NOT approved for use with Trek carbon-steerer forks.
05/24/2010
Updated installation procedures for stems on carbon steerers
Modern bicycles use high-tech materials and designs that rely on correct maintenance, precision workmanship, and compatibility of the parts. Mechanics must continue to learn the new procedures and requirements of these new bicycles. Incorrect mechanical work on a bicycle could lead to damage or breakage of a part, which could lead to a crash.
This bulletin includes information from an August 2009 Bontrager service bulletin, the Trek and Fisher bicycle owner’s manuals, 2010 Madone and Cronus assembly manuals, and new information.
Below the stem on all steerers
Always place at least one 5mm spacer below the stem. This spacer is in addition to the bearing cover, which must be at least 5mm. If the stem rests against the bearing cover, a point load is created on the steerer that could eventually cause the steerer to break.
Above the stem on carbon fiber steerers
With a carbon steerer, always place at least one 5mm spacer above the stem. A stem placed right at the top of the steerer can put too much force on the unsupported cut edge of the steerer, possibly crushing the steerer.
Check headset bearing preload
The bicycle owner’s manual tells a rider to check the bearing adjustment of the headset each month. With a carbon steerer, a rider should check more frequently. In addition to the checks in the owner’s manual, we recommend an additional quick check: the rider should check to make sure that the spacer(s) below the stem cannot be rotated with the fingers.
Tightening clamp bolts
When tightening clamp bolts on a carbon steerer or other carbon part, make sure to locate proper torque on the part or in the part’s manual and set the torque wrench correctly. Gradually tighten each steerer clamp bolt, alternating back and forth in small increments, until both bolts are at the correct torque. Use a similar method wherever there are multiple clamp bolts. Do not tighten one all the way before tightening the other, and do not leave the bolts with unequal torque.
Compatibility with all steerers
Make sure the stem clamp is designed correctly and is free of burrs. Correct design requires that the clamp is circumferential (closes in a circle); never use a wedge-type clamp. Also make sure the clamp bolts are tangential to the steerer. Angled clamp bolts can cause a point load along the clamp.
Clamp edges should be smooth and slightly rounded. If a stem has a sharp or burred edge, sliding it onto the steerer could scratch or cut the carbon fibers, which can weaken the steerer..
Compatibility with carbon steerers
With a carbon steerer, do not use a star-fangled nut; use only the compression nut assembly supplied with the fork. A star-fangled nut can scratch or cut carbon fibers, which can weaken the steerer.
With a carbon steerer, never use a stem with cutaways or holes in the back of the steerer clamp because this type of clamp can cause uneven pressure on the steerer. Uneven pressure, also called a point load, can damage the steerer. For contrast, the stem in Figure 5 (see PDF) does not have a cutaway.
With a carbon steerer, never use a stem with clamp bolts that require more than 55 lb•in (6 Nm) torque. Excessive torque can crush a carbon steerer.
Use a stem with a carbon-friendly design. The steerer clamp should have the maximum possible surface area and apply even pressure (it should not cause a point load). One cause of point loading is a cutaway in the stem, either in the back as mentioned above, or in a misplaced “lightening hole”. If the lightening hole is too close to the top or bottom of the stem, the narrow, remaining clamp area can cause a point load. To distribute the pressure evenly, the lightening hole should be at least 10mm from the top or the bottom of the stem. If a misplaced lightening hole is combined with incorrect spacers, the stem can crush the steerer. FSA stems are NOT approved for use with Trek carbon-steerer forks.
06-01-10, 07:03 AM
#31
Making a kilometer blurry
^^^^Looks like my signature 
I miss seeing my sig at work (since they killed imageshack here)
I miss seeing my sig at work (since they killed imageshack here)
06-01-10, 11:48 AM
#32
Senior Member
If I see this:
...regardless of what a torque wrench says, I loosen both bolts and start over, alternating tightening each bolt in small increments. One bolt should not be crimping the stem tighter than the other. Even if the torque wrench says they are at the same torque, the bolts might not be at the same tension, which is what you are really after.
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"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 11:53 AM
#33
Senior Member
A 20% increase in torque seems like it might cause some light weight components to break. The difference between 5 and 6nm is a fair amount.
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"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 12:09 PM
#34
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FWIW I have over torqued plenty of bolts in my day...90% of them lead to the bolt failing not the part. This includes lightweight components on race cars and bikes.
Last edited by El Diablo Rojo; 06-01-10 at 12:14 PM.
06-01-10, 12:22 PM
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Actually, sounds more like a cautious engineer wrote it.
If I see this:
...regardless of what a torque wrench says, I loosen both bolts and start over, alternating tightening each bolt in small increments. One bolt should not be crimping the stem tighter than the other. Even if the torque wrench says they are at the same torque, the bolts might not be at the same tension, which is what you are really after.
If I see this:
...regardless of what a torque wrench says, I loosen both bolts and start over, alternating tightening each bolt in small increments. One bolt should not be crimping the stem tighter than the other. Even if the torque wrench says they are at the same torque, the bolts might not be at the same tension, which is what you are really after.
06-01-10, 12:29 PM
#36
VeloSIRraptor
UPDATED: Service Information - Stems on Carbon Steerers
05/24/2010
Updated installation procedures for stems on carbon steerers
Below the stem on all steerers
Always place at least one 5mm spacer below the stem.
Above the stem on carbon fiber steerers
With a carbon steerer, always place at least one 5mm spacer above the stem.
05/24/2010
Updated installation procedures for stems on carbon steerers
Below the stem on all steerers
Always place at least one 5mm spacer below the stem.
Above the stem on carbon fiber steerers
With a carbon steerer, always place at least one 5mm spacer above the stem.
but, but, but.... my "pro" look... how ever will I get it now!?!
time to go look up images of Trek bikes as ridden by pros.... are they running spacers?
06-01-10, 01:24 PM
#38
Senior Member
Yeah but a steerer tube isn't a lightweight component...especially one that is sold to the general public. The lawyers usually have them over engineer that stuff anyway. Considering the twisting and other pressures being put on a steerer tube I'm surprised that 1n.m of torque is enough to induce a failure. One NM is .7 foot pounds...considering that unless you are anal about keeping your torque wrench in perfect calibration a .5nm of drift could be reasonably expected. If Trek is building bike for the general public's consumption with this level of tolerance they are stupid and opening themselves up to possible ligation.
FWIW I have over torqued plenty of bolts in my day...90% of them lead to the bolt failing not the part. This includes lightweight components on race cars and bikes.
FWIW I have over torqued plenty of bolts in my day...90% of them lead to the bolt failing not the part. This includes lightweight components on race cars and bikes.
2) Constriction is a different type of force than bending, which is the kind of external loads a steerer tube sees. Ever try bending a pop can along it's axis? Bet you can crush one with your bare hands easily enough though.
3) The torque wrench is the biggest load of BS the bike industry lawyers have brought onto the cycling public. The torque on a 4 or 5mm bolt has almost no relation to the tension the bolt is under, which is what you are really interested in. And as for the bolt stripping before the part, that went the way of 20+lb race bikes. Almost all the components on a modern racing bicycle will break before the steel bolts holding them together strip.
4) I agree with you about where Trek's priorities should be when it comes to product design. But the engineers are caught in the middle between the lawyers who want a 10lb frame that is bombproof and the marketeers who want a gossamer frame the weighs less and is stiffer than anything that will come out in the market in the forseeable future.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 01:24 PM
#39
Senior Member
BS. On both counts.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 01:39 PM
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1) A carbon steerer tube is a lightweight component. Otherwise, you make it out of aluminum or, god forbid, steel. CF has absolutely no redeeming qualities as a steerer tube material other than being lightweight.
2) Constriction is a different type of force than bending, which is the kind of external loads a steerer tube sees. Ever try bending a pop can along it's axis? Bet you can crush one with your bare hands easily enough though.
3) The torque wrench is the biggest load of BS the bike industry lawyers have brought onto the cycling public. The torque on a 4 or 5mm bolt has almost no relation to the tension the bolt is under, which is what you are really interested in. And as for the bolt stripping before the part, that went the way of 20+lb race bikes. Almost all the components on a modern racing bicycle will break before the steel bolts holding them together strip.
4) I agree with you about where Trek's priorities should be when it comes to product design. But the engineers are caught in the middle between the lawyers who want a 10lb frame that is bombproof and the marketeers who want a gossamer frame the weighs less and is stiffer than anything that will come out in the market in the forseeable future.
2) Constriction is a different type of force than bending, which is the kind of external loads a steerer tube sees. Ever try bending a pop can along it's axis? Bet you can crush one with your bare hands easily enough though.
3) The torque wrench is the biggest load of BS the bike industry lawyers have brought onto the cycling public. The torque on a 4 or 5mm bolt has almost no relation to the tension the bolt is under, which is what you are really interested in. And as for the bolt stripping before the part, that went the way of 20+lb race bikes. Almost all the components on a modern racing bicycle will break before the steel bolts holding them together strip.
4) I agree with you about where Trek's priorities should be when it comes to product design. But the engineers are caught in the middle between the lawyers who want a 10lb frame that is bombproof and the marketeers who want a gossamer frame the weighs less and is stiffer than anything that will come out in the market in the forseeable future.
2) Yes I understand that...that's why you lay up carbon differently depending on how you want it to withstand a load.
3) I can think if a bunch of parts that will strip before breaking but that is neither here or there. Carbon steerer tubes are supposed to be designed to take the forces applied, twisting, bending and compression.
4) You don't have to design a 10lb frame in order for it to not have a steerer tube that can hold up. I own a Scott R1 and it's lighter than the Madone yet we aren't reading about failures on that framesets steerer tubes.
06-01-10, 01:56 PM
#43
Making a kilometer blurry
06-01-10, 02:19 PM
#45
Senior Member
Anyhow... all I'm saying is that as much as we like to dump on Trek in this forum, the internets is littered with accounts of broken carbon steerer tubes... and frankly, most of them are attributable to user error. The companies then go back and revise their design to take better into account customer stupidity. On the plus side for them, they get the legalese about installation procedures that protects them, and they only weigh version 1 of the fork, so when they replace it with the customer proofed version 2 (which is heavier), they only mention the version 1 weight.
And it should surprise no one that some stems are gentler on carbon steerer tubes than others. It most likely has less to do with torque specs than it has to do with tolerances and clamp interface design. Bolt tension on its own has little to do with steerer tube failures. It's bolt tension combined with stress concentrations which cause the problems.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 02:22 PM
#46
Senior Member
Check out all the broken carbon bits here: https://pardo.net/bike/pic/fail-001/FAIL-069.html
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 02:28 PM
#47
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Eh. Some days... I even locked myself out of my house this morning when I forgot my keys inside.
Anyhow... all I'm saying is that as much as we like to dump on Trek in this forum, the internets is littered with accounts of broken carbon steerer tubes... and frankly, most of them are attributable to user error. The companies then go back and revise their design to take better into account customer stupidity. On the plus side for them, they get the legalese about installation procedures that protects them, and they only weigh version 1 of the fork, so when they replace it with the customer proofed version 2 (which is heavier), they only mention the version 1 weight.
And it should surprise no one that some stems are gentler on carbon steerer tubes than others. It most likely has less to do with torque specs than it has to do with tolerances and clamp interface design. Bolt tension on its own has little to do with steerer tube failures. It's bolt tension combined with stress concentrations which cause the problems.
Anyhow... all I'm saying is that as much as we like to dump on Trek in this forum, the internets is littered with accounts of broken carbon steerer tubes... and frankly, most of them are attributable to user error. The companies then go back and revise their design to take better into account customer stupidity. On the plus side for them, they get the legalese about installation procedures that protects them, and they only weigh version 1 of the fork, so when they replace it with the customer proofed version 2 (which is heavier), they only mention the version 1 weight.
And it should surprise no one that some stems are gentler on carbon steerer tubes than others. It most likely has less to do with torque specs than it has to do with tolerances and clamp interface design. Bolt tension on its own has little to do with steerer tube failures. It's bolt tension combined with stress concentrations which cause the problems.
I did this once, I went out to the garage to warm up my car in my underwear (garage was detached and in the back yard) and locked myself out of the house and locked the car. I had to go a neighbors house and borrow a phone to call AAA to get my keys...
I agree that quite a bit of the damage done to bike is done by the user (weather that be a shop mechanic or at home) f'n something up. I'm just saying that I find it pretty scary if 1n.m difference in torque is all it takes to cause a catastrophic failure in is such a critical part. I'm not disputing that parts can be broken by the misuse of a torque wrench but for Trek to claim that an FSA stem is not to be used due to an increase of torque requirements seems a bit fishy to me.
06-01-10, 02:39 PM
#48
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One of the steerer tubes that I saw fail broke on the start line of a crit. Whistle blows, rider clips in and starts accelerating, and *snap*.
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06-01-10, 02:50 PM
#49
Senior Member
...
I'm just saying that I find it pretty scary if 1n.m difference in torque is all it takes to cause a catastrophic failure in is such a critical part. I'm not disputing that parts can be broken by the misuse of a torque wrench but for Trek to claim that an FSA stem is not to be used due to an increase of torque requirements seems a bit fishy to me.
I'm just saying that I find it pretty scary if 1n.m difference in torque is all it takes to cause a catastrophic failure in is such a critical part. I'm not disputing that parts can be broken by the misuse of a torque wrench but for Trek to claim that an FSA stem is not to be used due to an increase of torque requirements seems a bit fishy to me.
To put it in perspective, 5-6nm torque, for a frictionless bolt, is likely wildly too high considering that friction makes up, easily, half the equation. So the lawyers/engineers have to bargain amongst themselves between a torque specification which won't leave the part too loose, and one which won't kill the components. But consider the friction on the threads. Which grease you use has a big role to play, or if you use grease at all. If you tighten one bolt completely before the other, this will misalign the second bolt, causing the friction to go through the roof (this is very likely what happened in the Ze's picture). Perhaps during the finishing process, some powdercoating got into the threads. What if it's a component being taken off a rain bike and the bolt has some corrosion on it?
You should tighten up components by hand, alternating bolts so the bolt holes stay aligned, and tighten them up just enough so the handlebars don't twist around the steerer tube. You should be able to feel when the two parts become engaged as you tighten things down; it feels different than simple thread friction. Once the clamp and the steering tube come together, you tighten by quarter or even 1/8 turns, one bolt at a time until the friction between the two pieces is enough to keep from twisting with respect to each other.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
06-01-10, 02:54 PM
#50
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The best advice is to ignore the torque specifications. They are useless on 4 or 5mm bolts, which is why you really don't find small torque wrenches in a standard hardware store. It really is only useful when you are talking about 1/2" bolts or larger, and even then, it's less useful than one might think. Smaller than that, friction is the dominant component of the torque on the wrench, and it doesn't correlate well with bolt tension, which is what everyone should be concerned about.
To put it in perspective, 5-6nm torque, for a frictionless bolt, is likely wildly too high considering that friction makes up, easily, half the equation. So the lawyers/engineers have to bargain amongst themselves between a torque specification which won't leave the part too loose, and one which won't kill the components. But consider the friction on the threads. Which grease you use has a big role to play, or if you use grease at all. If you tighten one bolt completely before the other, this will misalign the second bolt, causing the friction to go through the roof (this is very likely what happened in the Ze's picture). Perhaps during the finishing process, some powdercoating got into the threads. What if it's a component being taken off a rain bike and the bolt has some corrosion on it?
You should tighten up components by hand, alternating bolts so the bolt holes stay aligned, and tighten them up just enough so the handlebars don't twist around the steerer tube. You should be able to feel when the two parts become engaged as you tighten things down. Once the clamp and the steering tube come together, you tighten by quarter or even 1/8 turns, one bolt at a time until the friction between the two pieces is enough to keep from twisting with respect to each other.
To put it in perspective, 5-6nm torque, for a frictionless bolt, is likely wildly too high considering that friction makes up, easily, half the equation. So the lawyers/engineers have to bargain amongst themselves between a torque specification which won't leave the part too loose, and one which won't kill the components. But consider the friction on the threads. Which grease you use has a big role to play, or if you use grease at all. If you tighten one bolt completely before the other, this will misalign the second bolt, causing the friction to go through the roof (this is very likely what happened in the Ze's picture). Perhaps during the finishing process, some powdercoating got into the threads. What if it's a component being taken off a rain bike and the bolt has some corrosion on it?
You should tighten up components by hand, alternating bolts so the bolt holes stay aligned, and tighten them up just enough so the handlebars don't twist around the steerer tube. You should be able to feel when the two parts become engaged as you tighten things down. Once the clamp and the steering tube come together, you tighten by quarter or even 1/8 turns, one bolt at a time until the friction between the two pieces is enough to keep from twisting with respect to each other.