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Do you trust your handlebar stem?

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  41
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  16
Looking at the stem.... two bolts???? What was I thinking????? What a s**t design....  14
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  2
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....

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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41 comments

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surly_by_name replied to MKultra | 9 years ago
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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.

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MKultra replied to surly_by_name | 9 years ago
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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.

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glynr36 replied to MKultra | 9 years ago
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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...

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MKultra replied to glynr36 | 9 years ago
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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.

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gmac101 replied to MKultra | 9 years ago
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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.

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Chris James replied to glynr36 | 9 years ago
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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!  26

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surly_by_name replied to MKultra | 9 years ago
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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.[/quote]

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.

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southseabythesea | 9 years ago
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Ouch! I could add to that do you trust your LBS, when I got my cross bike home I gave it the once over and found that the headset bolts were loose even though they insisted giving it the once over before I took it home. Always check 'em with a torque key, bike shop or not.

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glynr36 | 9 years ago
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Perhaps you should title this 'Do you trust your bolts'

The stem didn't fail the bolt did, most likely due to over torquing it.
The second came out due to the abnormal load on it more than likely.

Invest in a torque wrench.

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Gasman Jim | 9 years ago
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I used to be a fan of the 2 bolt Thomson X2 stem.... until the faceplate deformed and wouldn't then grip the bars sufficiently to stop them rotating forwards when correctly torqued, (and I'm only 71kgs).

I now use the 4 bolt X4 stem on all my bikes. Much more secure.

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Al'76 | 9 years ago
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Not criticizing, but did you mount the bar using a torque wrench? Could see this happening if the bolt was done up silly tight, but like to think it would not happen under normal circumstances....

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