Do you trust your handlebar stem?

by SideBurn   May 29, 2014  

Riding home after a late shift at silly o'clock in the morning there was a loud bang; it was all I could do not to go over the front of the bike. It was dark and I had no idea what had happened. More to the point I was doing 30mph downhill. The bike swerved right, I hit the tarmac scraped down the road on my back, off the side of the road down an embankment and into a tree..... a downhill skier could not have done it any better 10 out of 10 for style Applause
Once I had checked all my body parts were in the correct place, I looked at my bike....
It appears that one of the two bolts holding the bars to the stem had snapped. The second bolt ripped out causing the handlebars to become detached.....
Luckily I had some electrical tape in my bag, I re-attached the bars and rode home Cool
Looking at the stem.... two bolts???? What was I thinking????? What a s**t design.... Angry
Maybe I am being a bit harsh; I have had this stem for some time and I have used it on unforgiving territory, or British roads as they are also known.
Anyway; I have skin missing on my face, shoulder, hip and knee along with very colourful bruises on both of my thighs. Not forgetting the general aches and pains..... I am feeling very sorry for myself Sad
I am writing this just to warn others to look very critically at their stem and ask yourself is it fit for purpose?
This incident could have been so much worse....

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Quote:
I am writing this just to warn others to look very critically at their stem and ask yourself is it fit for purpose?

Maybe *that* is what Chris Froome is doing?

http://chrisfroomelookingatstems.tumblr.com/

posted by farrell [1580 posts]
30th May 2014 - 9:11

8 Likes

Jimmy Ray Will wrote:

Truth is the stem/bar interface is never going to be that brilliant from an engineering point of view... but things have moved on significantly from those Millennium days.

I've noticed quite a few of the pros riding one-piece stem/bar combinations recently. Seems like a far more sensible approach to me.

Boardman CX Team '14 | Cannondale CAAD8 '12 (written off, SMIDSY) | Scott Sportster '08

Gizmo_'s picture

posted by Gizmo_ [958 posts]
30th May 2014 - 9:59

5 Likes

When you design a bolted connection like stem / bar joint you calculate the tension in the bolt that gives you a strong enough joint. The problem is that measuring the tension in the bolt is pretty tricky without special equipment so the most practical thing to do is measure the torque you impose on the nut or the bolt head as a "proxy" for the actual bolt tension. The problem is that it's not very accurate! It's a classic first year engineering degree lab to torque up a series of bolts in different conditions and then measure the actual tension in the bolt. If I remember correctly it's about +/- 25% accurate. The problem is that friction in the bolt/nut system eats up the torque and very little is used to actually tension the bolt but the friction in the system is also very dependent on condition. Some factors include, bolt & nut material, type of grease used (if any) location of the grease on the bolt, foreign bodies & corrosion. If you don't replicate the conditions the manufacturer assumed when they worked out the recommended torque you could be a long way out from the bolt tension intended. And of course we are all using calibrated torque wrenches aren't we? So Dr Fabulous0 when you torqued up to the manufacturers recommendation you may well have prepared the bolt better the manufacturer expected and so didn't reach the required tension.

posted by gmac101 [35 posts]
30th May 2014 - 22:42

7 Likes

Jimmy Ray Will wrote:
ITM Millennium!!! Isn't that over 10 years old? I think that, right there is your problem.

Truth is the stem/bar interface is never going to be that brilliant from an engineering point of view... but things have moved on significantly from those Millennium days.

Muchos kudos for simply taping your bars back on and riding home... that is truly hardcore!

Get well soon.

Oh dear, you've got me worried about my 40+ year old bike on which I'm planning to ride the Retro Ronde.

Will it fall apart on the cobbles? Is there any way to check, short of ultrasonic inspection?.

Crosshouses's picture

posted by Crosshouses [216 posts]
1st June 2014 - 18:31

4 Likes

I have never had a stem fail on me or a bolt snap (for now touch wood), I also have never used a torque wrench on ally or steel stems.

With the exception of carbon where it is critical to get it right with a torque wrench I would be of the opinion that if you don't have the feel for getting it right yourself with just an alan key then perhaps you should be taking it to the LBS rather than doing it yourself.

I await the storm of pedantic rage but be honest chaps, buying a torque wrench is not a cure for being cack handed.

posted by MKultra [286 posts]
2nd June 2014 - 11:17

5 Likes

Crosshouses wrote:
Jimmy Ray Will wrote:
ITM Millennium!!! Isn't that over 10 years old? I think that, right there is your problem.

Truth is the stem/bar interface is never going to be that brilliant from an engineering point of view... but things have moved on significantly from those Millennium days.

Muchos kudos for simply taping your bars back on and riding home... that is truly hardcore!

Get well soon.

Oh dear, you've got me worried about my 40+ year old bike on which I'm planning to ride the Retro Ronde.

Will it fall apart on the cobbles? Is there any way to check, short of ultrasonic inspection?.

Looking at my 30+ year old bike/stems they are very solid looking and look better engineered than this relatively modern stem. I have never known one ancient or modern breaking. I am reassured that no one seems to be saying, "This has happened to me...."
Suggests I am just unlucky...

posted by SideBurn [873 posts]
2nd June 2014 - 14:56

3 Likes

MKultra wrote:

I await the storm of pedantic rage but be honest chaps, buying a torque wrench is not a cure for being cack handed.

That's exactly what it is a cure for, do bolt up to specified torque, then stop.
Not, tighten, tighten, tighten, and then a bit more till you think you got 11.8Nm

The thing is most people don't realise just how little 15Nm and less is, especially when they're swinging off the end of an XL length Allen key.

You can even get the ones that stop going beyond the set torque if you're really stupid/hamfisted.

glynr36's picture

posted by glynr36 [506 posts]
2nd June 2014 - 15:21

4 Likes

Not quite happened to me, but my clubmate's stem faceplate cracked. Luckily I happened to notice it when we were stopped, so a careful ride thereafter, no swinging out of the saddle. Stem binned.

I've had a nosebolt go on a Cinelli 1A stem, but that was due to overtightening. Very hard to get them tight enough to stop the bars moving if you hit a hole. After such an incident I wanged it up. Next day, speeding throguh some village in the Ras - BANG - bars shoot round and flop sideways. Lucky to stay upright there.

posted by racyrich [152 posts]
2nd June 2014 - 15:46

3 Likes

gmac101 wrote:
When you design a bolted connection like stem / bar joint you calculate the tension in the bolt that gives you a strong enough joint. The problem is that measuring the tension in the bolt is pretty tricky without special equipment so the most practical thing to do is measure the torque you impose on the nut or the bolt head as a "proxy" for the actual bolt tension. The problem is that it's not very accurate! It's a classic first year engineering degree lab to torque up a series of bolts in different conditions and then measure the actual tension in the bolt. If I remember correctly it's about +/- 25% accurate. The problem is that friction in the bolt/nut system eats up the torque and very little is used to actually tension the bolt but the friction in the system is also very dependent on condition. Some factors include, bolt & nut material, type of grease used (if any) location of the grease on the bolt, foreign bodies & corrosion. If you don't replicate the conditions the manufacturer assumed when they worked out the recommended torque you could be a long way out from the bolt tension intended. And of course we are all using calibrated torque wrenches aren't we? So Dr Fabulous0 when you torqued up to the manufacturers recommendation you may well have prepared the bolt better the manufacturer expected and so didn't reach the required tension.

I love this kind of stuff. Genuinely. I wish I knew about engineering.

posted by jellysticks [86 posts]
2nd June 2014 - 17:18

6 Likes

I remember these ITM 2 bolt stems failing about 10 years ago, the bolts were gash and there was the torque vs thread friction issues.

All Campag

posted by Flying Scot [676 posts]
2nd June 2014 - 18:31

3 Likes

Flying Scot wrote:
I remember these ITM 2 bolt stems failing about 10 years ago, the bolts were gash and there was the torque vs thread friction issues.

I have been lucky for 10 years? Plain Face

posted by SideBurn [873 posts]
2nd June 2014 - 20:30

4 Likes

Careful Jellysticks who you say things like that to - most engineers can talk for hours about this rubbish if you let them - Let me tell you about inviscid hydrodynamics......

posted by gmac101 [35 posts]
2nd June 2014 - 21:20

6 Likes

SideBurn wrote:
Flying Scot wrote:
I remember these ITM 2 bolt stems failing about 10 years ago, the bolts were gash and there was the torque vs thread friction issues.

I have been lucky for 10 years? Plain Face

Possibly, I just remember reading about it before, though they werent the only ones, I've no experience of it myself.

I'm using a 20 year old titanium quill stem on my road bike.

All Campag

posted by Flying Scot [676 posts]
2nd June 2014 - 22:17

3 Likes

Glad you survived in one piece, a 30mph tumble in the dark must be horrific.
Outside of cycling, I enjoy a spot of rock climbing and it's interesting to compare the industry response when equipment fails like this. In the event of safety equipment failure, the standard practice is to send it straight back to the manufacturers, who by and large are incredibly responsive - precautionary recalls are not at all uncommon. SRAM hydraulic brakes aside, cycling manufacturers seem less bothered?

dafyddp's picture

posted by dafyddp [181 posts]
3rd June 2014 - 9:51

2 Likes

drfabulous0 wrote:
Two bolts is a poor design as you now realise, if they are not tightened evenly then one can be taking excessive force, four bolts or one are better.

I've been a bike mechanic for many years and I have to warn you guys not to put to much faith in reccommended torque settings, it is not uncommon to do up stem bolts to the manufacturer's specification and find that the bars will slip under a slight load. An experienced mechanic can not only make a fair estimate of torque without the torque wrench but can also feel when the bolts are under sufficient but not excess tension.

Two bolts no worse than 4: http://www.eastoncycling.com/bike/wp-content/uploads/2010/04/RD-06-2Bolt... (Although now Easton have followed the fashion to 4 bolts, suspect you can't find this paper so easily on their website anymore.)

The bigger problem is not a faceplate that is too loose at recommended torque settings but one that is overtightened by someone who doesn't have the benefit of a torque wrench.

And the bit about "experienced" mechanics being magical - leaving aside the fact that this is a fairy tale, a mechanic who doesn't own/use a torque wrench doesn't deserve the sobriquet "experienced".

posted by surly_by_name [177 posts]
3rd June 2014 - 13:22

3 Likes

surly_by_name wrote:
drfabulous0 wrote:
Two bolts is a poor design as you now realise, if they are not tightened evenly then one can be taking excessive force, four bolts or one are better.

I've been a bike mechanic for many years and I have to warn you guys not to put to much faith in reccommended torque settings, it is not uncommon to do up stem bolts to the manufacturer's specification and find that the bars will slip under a slight load. An experienced mechanic can not only make a fair estimate of torque without the torque wrench but can also feel when the bolts are under sufficient but not excess tension.

Two bolts no worse than 4: http://www.eastoncycling.com/bike/wp-content/uploads/2010/04/RD-06-2Bolt... (Although now Easton have followed the fashion to 4 bolts, suspect you can't find this paper so easily on their website anymore.)

The bigger problem is not a faceplate that is too loose at recommended torque settings but one that is overtightened by someone who doesn't have the benefit of a torque wrench.

And the bit about "experienced" mechanics being magical - leaving aside the fact that this is a fairy tale, a mechanic who doesn't own/use a torque wrench doesn't deserve the sobriquet "experienced".

So they were all rubbish before carbon came along and torque wrenches were needed?

Piffle.

It's the over complication of the subject/trade by middle class people with more money than sense, much like when they all thought they could retrain as plumbers back in the early noughties.

No it's not magical but neither is throwing money about or snobbery.

posted by MKultra [286 posts]
3rd June 2014 - 15:55

3 Likes

MKultra wrote:
So they were all rubbish before carbon came along and torque wrenches were needed?

Piffle.

It's the over complication of the subject/trade by middle class people with more money than sense, much like when they all thought they could retrain as plumbers back in the early noughties.

No it's not magical but neither is throwing money about or snobbery.

My father - who I don't think was unusual among his generation - was able to work on the engine of his car. I seem to have a vague recollection of him having the top of the cyclinders off on at least one occasion. You would open the bonnet and there were all of the mysteries of the internal combustion engine laid out in front of you (with lots of extra room to stick your head in and swear when things didn't work as they were supposed to). The ECU in a modern vehicle (or a hybrid engine) isn't the kind of thing you fix on your driveway on a Saturday morning.

I don't think mechanics were rubbish before carbon came along. I think they were skilled in working with the technology they had in front of them. Technology has, I imagine you will concede, moved on a bit.

A BBB torque wrench costs c.£45. If this is too bourgeoisie for you, you can purchase a Ritchey torque key (with a 5/4/3 and T15 bit) which will let you know when you've reached 5nM (recommended for most stem bolts at steerer and handlebar; in fact probably about the correct torque for pretty much every bolt on a road bike you want to tighten regularly (bottle cage bolts, seat pin collar (although my Thomson collar has a ludicrously low torque setting of 2.8nM - try and get that right by hand) - not cranks or pedals) for a much more proletarian £12.

Nothing is without risk. Using a torque wrench and following manufacturers recommended torque settings is a (not particularly expensive, empirical) means of managing some of the risks inherent in working on your own bike. (Or you can manage the risk by taking your bike to a shop.) If you don't follow manufacturers instructions and something goes wrong then its easy to lose the argument that it was partly your fault.

If you spend a lot of money on bikes and parts (particularly lightweight parts, whether in carbon or aluminium) and you don't use a torque wrench (or you rely on a mechanic who doesn't use a torque wrench) you are an idiot.

posted by surly_by_name [177 posts]
4th June 2014 - 9:49

3 Likes

surly_by_name wrote:
MKultra wrote:
So they were all rubbish before carbon came along and torque wrenches were needed?

Piffle.

It's the over complication of the subject/trade by middle class people with more money than sense, much like when they all thought they could retrain as plumbers back in the early noughties.

No it's not magical but neither is throwing money about or snobbery.

My father - who I don't think was unusual among his generation - was able to work on the engine of his car. I seem to have a vague recollection of him having the top of the cyclinders off on at least one occasion. You would open the bonnet and there were all of the mysteries of the internal combustion engine laid out in front of you (with lots of extra room to stick your head in and swear when things didn't work as they were supposed to). The ECU in a modern vehicle (or a hybrid engine) isn't the kind of thing you fix on your driveway on a Saturday morning.

I don't think mechanics were rubbish before carbon came along. I think they were skilled in working with the technology they had in front of them. Technology has, I imagine you will concede, moved on a bit.

A BBB torque wrench costs c.£45. If this is too bourgeoisie for you, you can purchase a Ritchey torque key (with a 5/4/3 and T15 bit) which will let you know when you've reached 5nM (recommended for most stem bolts at steerer and handlebar; in fact probably about the correct torque for pretty much every bolt on a road bike you want to tighten regularly (bottle cage bolts, seat pin collar (although my Thomson collar has a ludicrously low torque setting of 2.8nM - try and get that right by hand) - not cranks or pedals) for a much more proletarian £12.

Nothing is without risk. Using a torque wrench and following manufacturers recommended torque settings is a (not particularly expensive, empirical) means of managing some of the risks inherent in working on your own bike. (Or you can manage the risk by taking your bike to a shop.) If you don't follow manufacturers instructions and something goes wrong then its easy to lose the argument that it was partly your fault.

If you spend a lot of money on bikes and parts (particularly lightweight parts, whether in carbon or aluminium) and you don't use a torque wrench (or you rely on a mechanic who doesn't use a torque wrench) you are an idiot.

The fact that you have manged to write 5 paragraphs defending the gross over complication of a simple mechanical task that the non-cack handed among us can do with their eyes shut just proves me right.

posted by MKultra [286 posts]
4th June 2014 - 11:07

3 Likes

MKultra wrote:

The fact that you have manged to write 5 paragraphs defending the gross over complication of a simple mechanical task that the non-cack handed among us can do with their eyes shut just proves me right.

Over complication? Its the way it should be done properly.
And you say non-cack handed, how do you know your bolts are in the right torque range, suggests a lack of engineering knowledge...

glynr36's picture

posted by glynr36 [506 posts]
4th June 2014 - 11:45

1 Like

The only time I've ever sheared a bolt head was when using a torque wrench, that was also on a stem faceplate.

posted by PaulBox [16 posts]
4th June 2014 - 12:04

0 Likes

glynr36 wrote:
MKultra wrote:

The fact that you have manged to write 5 paragraphs defending the gross over complication of a simple mechanical task that the non-cack handed among us can do with their eyes shut just proves me right.

Over complication? Its the way it should be done properly.
And you say non-cack handed, how do you know your bolts are in the right torque range, suggests a lack of engineering knowledge...


A torque wrench is only as good as it's last re calibration. Some components such as very proprietary lightweight ally or carbon indeed need one, getting all sniffy about them though is just stupid. A bike is not just a high maintenance toy for sportive use, it needs to be reliable day in day out and often on tour so it needs to be repairable in the field with simple tools.

A torque wrench is not one of them and components that only function within a narrow range of torque are not fit for purpose IMHO.

posted by MKultra [286 posts]
4th June 2014 - 12:17

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- coincidentally was checking out stems on Rose's website earlier today and came across the following advice:
"For your safety, please change aluminium stems and handlebars after two years or 5000 km at the latest. After a fall you should change these parts immediately."
Does ANYONE do this? 5000 kms? !!!

posted by youngoldbloke [81 posts]
4th June 2014 - 12:40

0 Likes

MKultra wrote:
The fact that you have manged to write 5 paragraphs defending the gross over complication of a simple mechanical task that the non-cack handed among us can do with their eyes shut just proves me right.

I wasn't defending anything. I just thought I should make some some attempt at polite conversation to soften the conclusion (i.e., you are an idiot). Also, I like the sound of my own voice. This is a failing I am working on. But you are still an idiot.

posted by surly_by_name [177 posts]
4th June 2014 - 12:55

0 Likes

youngoldbloke wrote:
Does ANYONE do this? 5000 kms? !!!

Designed to allow manufacturers to avoid liability. Hard to know if it would work (how would you ascertain whether distance had in fact been reached) and not - so far as I am aware - tested, but I imagine they'd try it on (or their insurers would).

posted by surly_by_name [177 posts]
4th June 2014 - 12:57

0 Likes

MKultra wrote:
glynr36 wrote:
MKultra wrote:

The fact that you have manged to write 5 paragraphs defending the gross over complication of a simple mechanical task that the non-cack handed among us can do with their eyes shut just proves me right.

Over complication? Its the way it should be done properly.
And you say non-cack handed, how do you know your bolts are in the right torque range, suggests a lack of engineering knowledge...


A torque wrench is only as good as it's last re calibration. Some components such as very proprietary lightweight ally or carbon indeed need one, getting all sniffy about them though is just stupid. A bike is not just a high maintenance toy for sportive use, it needs to be reliable day in day out and often on tour so it needs to be repairable in the field with simple tools.

A torque wrench is not one of them and components that only function within a narrow range of torque are not fit for purpose IMHO.

Well if you don't like torque wrenches you could always count turns. In increasing order of accuracy methods of tensioning bolts are:

1: Experienced Mechanic
2: Torque Wrench
3: Counting Turns
4: Tension Indicating washers
5: Bolt tensioning equipment.

Counting turns does however mean having accurate measurements of the joint, knowing the thread pitch and the mechanical properties of the materials so you work out the geometry change you need to induce the correct tension.

You are right of course that the increasing number of torque markings on your average bike is an indication that the gap between the load required to make the joint work and the load that would result in the failure of one or more components is decreasing and you have to wonder given the inherent inaccuracy in the measurement method used if it's the right direction to go in.

posted by gmac101 [35 posts]
4th June 2014 - 22:12

2 Likes

surly_by_name wrote:
youngoldbloke wrote:
Does ANYONE do this? 5000 kms? !!!

Designed to allow manufacturers to avoid liability. Hard to know if it would work (how would you ascertain whether distance had in fact been reached) and not - so far as I am aware - tested, but I imagine they'd try it on (or their insurers would).


I have got one of those bikes that are 30 years+ old (honest Liar ) but where I have changed everything on it at least once. The last thing I changed was the aluminium bars; they are now hanging on my wall Cool
Along with an ITM stem Sad
Great discussion going on

posted by SideBurn [873 posts]
5th June 2014 - 9:55

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I started building custom wheels recently so have learned a thing or two about liability, as well as real shelf life of bicycle components.

All the bits on your bike fall somewhere on the weight/ durability spectrum. Older stuff, like quill stems, were very durable, but the industry ceded durability for weight in the 90s. These days you can buy a bike for not a lot that's half the weight of Bernard Hinault's bike, but I can guarantee it won't last as long when subjected to the same use/ abuse.

Stems are much the same as spokes (and anything else); they have a certain number of cycles they can tolerate before failure. 10 years for an alloy stem may be a long time, but it's more dependent on the use you've put it through in that time.

2 years for a stem is legally right; almost all people will not put a stem through enough abuse for it to fail in that time. Beyond that and it becomes a matter of rider weight/ road quality/ weather exposure. Chances are a stem will last a decade if ridden on smooth roads by a light rider on sunny days, but from a liability perspective you can't guarantee that and so have to mandate a shorter shelf life, so you don't get sued if your product eventually fails and causes an accident.

posted by Gordy748 [98 posts]
5th June 2014 - 18:35

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Fatigue needs two things to do damage to a structure:

1/ repeated cyclical stress
2/ a stress concentration

So if an item is unused it won't fatigue, it might corrode, but it won't fatigue.

So time limits set by manufacturers are probably based on moderately heavy usage to suit their insurers. Stress cycles close to the failure load of the structure cause a lot more fatigue damage than smaller loads so they probably make adverse assumptions regarding rider weight and road smoothness.

Stress concentrations can come from 3 sources - Poor design, manufacturing defects and corrosion. Poor design is pretty rare these days as the risks are well known. Many fatigue failures result from manufacturing defects, and these mostly come from welds, getting a weld right is not a trivial task and all kinds of defects can lurk unseen in the body of a weld and these defects will often be in the form of cracks which generate stress concentrations at their tips and you get fatigue. Castings reduce the risk of defects but a poorly executed cast can also contain defects, if you are looking with suspicion at your stem following this conversation the manufacturing process with probably the smallest risk of fatigue is forging - but you normally pay extra for that.
Corrosion can generate changes in profile and cause cracks so even if the corrosion has not resulted much loss of material it will increase the risk of fatigue damage.
By the way I ride a bike with a welded 2 bolt stem, but it's from a reputable manufacturer who I'm sure will have engineered the weld and have appropriate QA procedures that will significantly reduce the risk of a defect that's likely to result in fatigue damage

posted by gmac101 [35 posts]
8th June 2014 - 22:25

1 Like

gmac101 wrote:
Fatigue needs two things to do damage to a structure:

1/ repeated cyclical stress
2/ a stress concentration

So if an item is unused it won't fatigue, it might corrode, but it won't fatigue.

So time limits set by manufacturers are probably based on moderately heavy usage to suit their insurers. Stress cycles close to the failure load of the structure cause a lot more fatigue damage than smaller loads so they probably make adverse assumptions regarding rider weight and road smoothness.

Stress concentrations can come from 3 sources - Poor design, manufacturing defects and corrosion. Poor design is pretty rare these days as the risks are well known. Many fatigue failures result from manufacturing defects, and these mostly come from welds, getting a weld right is not a trivial task and all kinds of defects can lurk unseen in the body of a weld and these defects will often be in the form of cracks which generate stress concentrations at their tips and you get fatigue. Castings reduce the risk of defects but a poorly executed cast can also contain defects, if you are looking with suspicion at your stem following this conversation the manufacturing process with probably the smallest risk of fatigue is forging - but you normally pay extra for that.
Corrosion can generate changes in profile and cause cracks so even if the corrosion has not resulted much loss of material it will increase the risk of fatigue damage.
By the way I ride a bike with a welded 2 bolt stem, but it's from a reputable manufacturer who I'm sure will have engineered the weld and have appropriate QA procedures that will significantly reduce the risk of a defect that's likely to result in fatigue damage


So the mistake I made was to purchase AND use the stem?
And are you saying ITM are not a reputable manufacturer? Controversial.....

posted by SideBurn [873 posts]
9th June 2014 - 8:14

0 Likes

glynr36 wrote:
MKultra wrote:

The fact that you have manged to write 5 paragraphs defending the gross over complication of a simple mechanical task that the non-cack handed among us can do with their eyes shut just proves me right.

Over complication? Its the way it should be done properly.
And you say non-cack handed, how do you know your bolts are in the right torque range, suggests a lack of engineering knowledge...

I hesitate to get involved in this 'ahem' discussion, but from a personal point of view I have been cycling for around 30 years, doing all my home mechanicing. I have never used a torque wrench on any of my fasteners (I only have steel and alloy frames and parts though).

I have never had a fastener or component fail through over or under tightening in that time. That doesn't mean that I think torque wrenches are useless, just that I haven't got one and have never felt the need to buy one.

I have a degree in Mechanical Engineering, and have worked for the last 20 years in various engineering and quality roles in the aerospace industry. The last 11 of which in the field of fastener production and distribution!

On a pedantic note, there are very few 'bolts' on a bike. they are mostly screws! Nerd

posted by Chris James [215 posts]
9th June 2014 - 8:35

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