Torque wrench question

Peter Chisholm said:

Quoted message said:

Quoted message said:

I'm a bike mechanic, not a car mechanic but every decent, non-car
dealer' wrench I have ever talked to uses a torque wrench on things
like drive train bolts and head bolts. IT is NOT a rudimentary part of
mechanical skill. It is the lazy mechanic that doesn't take the few
extra seconds to use a torque wrnch instead of just a 'wrench'. The
difference between a good mechanic and a great one.

I replied:

Quoted message said:

Quoted message said:

Yes, I've long maintained that torque wrenches are automotive tools.

I'm not sure what you mean by "drive train bolts" but certainly it is
proper to use a torque wrench on head bolts or other applications that
rely on gaskets getting crushed just the right amount.

However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown
+-----------------------------------------------------+
| Why can’t computer scientists tell the difference |
| between Christmas and Halloween? |
| |
| |
| |
| |
| |
| |
| |
| DEC 25 = OCT 31 |
+-----------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Peter Chisholm said:

Quoted message said:

Quoted message said:

I'm a bike mechanic, not a car mechanic but every decent, non-car
dealer' wrench I have ever talked to uses a torque wrench on things
like drive train bolts and head bolts. IT is NOT a rudimentary part of
mechanical skill. It is the lazy mechanic that doesn't take the few
extra seconds to use a torque wrnch instead of just a 'wrench'. The
difference between a good mechanic and a great one.

I replied:

Quoted message said:

Quoted message said:

Yes, I've long maintained that torque wrenches are automotive tools.

I'm not sure what you mean by "drive train bolts" but certainly it is
proper to use a torque wrench on head bolts or other applications that
rely on gaskets getting crushed just the right amount.

However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown
+-----------------------------------------------------+
| Why can’t computer scientists tell the difference |
| between Christmas and Halloween? |
| |
| |
| |
| |
| |
| |
| |
| DEC 25 = OCT 31 |
+-----------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Peter Chisholm said:

Quoted message said:

Quoted message said:

I'm a bike mechanic, not a car mechanic but every decent, non-car
dealer' wrench I have ever talked to uses a torque wrench on things
like drive train bolts and head bolts. IT is NOT a rudimentary part of
mechanical skill. It is the lazy mechanic that doesn't take the few
extra seconds to use a torque wrnch instead of just a 'wrench'. The
difference between a good mechanic and a great one.

I replied:

Quoted message said:

Quoted message said:

Yes, I've long maintained that torque wrenches are automotive tools.

I'm not sure what you mean by "drive train bolts" but certainly it is
proper to use a torque wrench on head bolts or other applications that
rely on gaskets getting crushed just the right amount.

However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown
+-----------------------------------------------------+
| Why can’t computer scientists tell the difference |
| between Christmas and Halloween? |
| |
| |
| |
| |
| |
| |
| |
| DEC 25 = OCT 31 |
+-----------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Sheldon Brown said:

Peter Chisholm said:

Quoted message said:

>I'm a bike mechanic, not a car mechanic but every decent, non-car
>dealer' wrench I have ever talked to uses a torque wrench on things
>like drive train bolts and head bolts. IT is NOT a rudimentary part of
>mechanical skill. It is the lazy mechanic that doesn't take the few
>extra seconds to use a torque wrnch instead of just a 'wrench'. The
>difference between a good mechanic and a great one.

I replied:

Quoted message said:

Quoted message said:

Yes, I've long maintained that torque wrenches are automotive tools.

I'm not sure what you mean by "drive train bolts" but certainly it is
proper to use a torque wrench on head bolts or other applications that
rely on gaskets getting crushed just the right amount.

However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown

To Sheldon's point, if the left crank needs to be tightened harder
than the right one, following a rote torque value certainly /would
result in a deviation from optimal. I'm just not resigned to the idea
that this deviation would be greater than the deviation resulting from
your average person torquing the same cranks by feel alone.

I found the below article rather interesting.

My theory, after looking at it, is: I'll defer to the Sheldons and
Lennards and Peters of this world as to the criticality of torque
accuracy on bicycle fasteners, but will also presume that I'm going to
be more accurate (with proper use of a properly-calibrated torque
wrench, obtaining accurate torque values in the first place, and
appropriately lubricating the fasteners) than going by *my* decidedly
uncalibrated arm. YMMV.
----
http://www.unbrako.com/docs/Fastener%20Facts.pdf
----
Quoting:

METHODS for CONTROLLING TIGHTNESS
Six methods can be used to control tightness of a threaded fastener.
In order of increasing accuracy - and increasing cost - they are:

Method Accuracy Relative Costs
Feel +/-35% 1
Torque wrench +/-25% 1-1/2
Turn-of-the-nut +/-15% 3
PLI washers +/-10% 7
Bolt elongation +/-3-5% 15
Strain gages +/-1% 20

But this table only tells part of the story. The less the accuracy of
the tightening method the greater must be the minimum yield strength
of the fastener in order to compensate for preload variations and to
insure a minimum clamping force. This can be done only be using a
fastener material of greater strength or increasing fastener size -
both of which will increase the cost of the fastener.

The decision as to which tightening method to use depends primarily on
the criticality of the joint. Generally, the more critical the joint
the more need for higher tightening accuracy and the greater the cost
for obtaining the right clamping force. It should always be noted that
the method selected will almost always lie between the two extremes,
for few applications will allow the high inaccuracy of the "feel"
method, while the high cost, highly accurate strain gages are used
almost entirely in the laboratory. The other methods
may be summarized as follows:

TORQUE WRENCH

This is the least expensive of the accepted methods of controlling
fastener preload but is the least accurate, chiefly because the
reading on dial is affected by the friction to be overcome.

TURN-OF-THE-NUT

In this method, the nut or bolt is turned a predetermined number of
degrees after all play has been removed from the joint.
How much to turn the nut or bolt cannot be calculated (because of the
"rubberiness" of the joint) but must be developed by tests for each
joint. It eliminates the friction factor; however, its accuracy is
affected by the care of the workman in measuring the angle the
nut or bolt is turned.

PRELOAD INDICATING WASHERS

Preload indicating (PLI) washers utilize compression of an inner ring
between two flat washers with an outer indicating washer for control.
As the load increases, the inner ring, which is higher than the outer
one, is squeezed down and enlarged in diameter until the
outer washer binds against two flat washers. When the inner ring has
been flattened to this point, the correct clamping force has been
reached. The PLI washer is sensitive only to axial load.

BOLT ELONGATION

In this method, a bolt from the lot is loaded in a tensile machine
with the same nut as used in the application. The distance from the
nut face to the underside of the bolt head is measured, and a plot is
made of bolt elongation in relation to induced load. In the
application, the fastener is tightened and the bolt elongation is
measured until the required preload as determined from the plot has
been achieved.

--
Live simply so that others may simply live

Sheldon Brown said:

Peter Chisholm said:

Quoted message said:

>I'm a bike mechanic, not a car mechanic but every decent, non-car
>dealer' wrench I have ever talked to uses a torque wrench on things
>like drive train bolts and head bolts. IT is NOT a rudimentary part of
>mechanical skill. It is the lazy mechanic that doesn't take the few
>extra seconds to use a torque wrnch instead of just a 'wrench'. The
>difference between a good mechanic and a great one.

I replied:

Quoted message said:

Quoted message said:

Yes, I've long maintained that torque wrenches are automotive tools.

I'm not sure what you mean by "drive train bolts" but certainly it is
proper to use a torque wrench on head bolts or other applications that
rely on gaskets getting crushed just the right amount.

However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown

To Sheldon's point, if the left crank needs to be tightened harder
than the right one, following a rote torque value certainly /would
result in a deviation from optimal. I'm just not resigned to the idea
that this deviation would be greater than the deviation resulting from
your average person torquing the same cranks by feel alone.

I found the below article rather interesting.

My theory, after looking at it, is: I'll defer to the Sheldons and
Lennards and Peters of this world as to the criticality of torque
accuracy on bicycle fasteners, but will also presume that I'm going to
be more accurate (with proper use of a properly-calibrated torque
wrench, obtaining accurate torque values in the first place, and
appropriately lubricating the fasteners) than going by *my* decidedly
uncalibrated arm. YMMV.
----
http://www.unbrako.com/docs/Fastener%20Facts.pdf
----
Quoting:

METHODS for CONTROLLING TIGHTNESS
Six methods can be used to control tightness of a threaded fastener.
In order of increasing accuracy - and increasing cost - they are:

Method Accuracy Relative Costs
Feel +/-35% 1
Torque wrench +/-25% 1-1/2
Turn-of-the-nut +/-15% 3
PLI washers +/-10% 7
Bolt elongation +/-3-5% 15
Strain gages +/-1% 20

But this table only tells part of the story. The less the accuracy of
the tightening method the greater must be the minimum yield strength
of the fastener in order to compensate for preload variations and to
insure a minimum clamping force. This can be done only be using a
fastener material of greater strength or increasing fastener size -
both of which will increase the cost of the fastener.

The decision as to which tightening method to use depends primarily on
the criticality of the joint. Generally, the more critical the joint
the more need for higher tightening accuracy and the greater the cost
for obtaining the right clamping force. It should always be noted that
the method selected will almost always lie between the two extremes,
for few applications will allow the high inaccuracy of the "feel"
method, while the high cost, highly accurate strain gages are used
almost entirely in the laboratory. The other methods
may be summarized as follows:

TORQUE WRENCH

This is the least expensive of the accepted methods of controlling
fastener preload but is the least accurate, chiefly because the
reading on dial is affected by the friction to be overcome.

TURN-OF-THE-NUT

In this method, the nut or bolt is turned a predetermined number of
degrees after all play has been removed from the joint.
How much to turn the nut or bolt cannot be calculated (because of the
"rubberiness" of the joint) but must be developed by tests for each
joint. It eliminates the friction factor; however, its accuracy is
affected by the care of the workman in measuring the angle the
nut or bolt is turned.

PRELOAD INDICATING WASHERS

Preload indicating (PLI) washers utilize compression of an inner ring
between two flat washers with an outer indicating washer for control.
As the load increases, the inner ring, which is higher than the outer
one, is squeezed down and enlarged in diameter until the
outer washer binds against two flat washers. When the inner ring has
been flattened to this point, the correct clamping force has been
reached. The PLI washer is sensitive only to axial load.

BOLT ELONGATION

In this method, a bolt from the lot is loaded in a tensile machine
with the same nut as used in the application. The distance from the
nut face to the underside of the bolt head is measured, and a plot is
made of bolt elongation in relation to induced load. In the
application, the fastener is tightened and the bolt elongation is
measured until the required preload as determined from the plot has
been achieved.

--
Live simply so that others may simply live

Sheldon Brown said:

Peter Chisholm said:

Quoted message said:

>I'm a bike mechanic, not a car mechanic but every decent, non-car
>dealer' wrench I have ever talked to uses a torque wrench on things
>like drive train bolts and head bolts. IT is NOT a rudimentary part of
>mechanical skill. It is the lazy mechanic that doesn't take the few
>extra seconds to use a torque wrnch instead of just a 'wrench'. The
>difference between a good mechanic and a great one.

I replied:

Quoted message said:

Quoted message said:

Yes, I've long maintained that torque wrenches are automotive tools.

I'm not sure what you mean by "drive train bolts" but certainly it is
proper to use a torque wrench on head bolts or other applications that
rely on gaskets getting crushed just the right amount.

However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown

To Sheldon's point, if the left crank needs to be tightened harder
than the right one, following a rote torque value certainly /would
result in a deviation from optimal. I'm just not resigned to the idea
that this deviation would be greater than the deviation resulting from
your average person torquing the same cranks by feel alone.

I found the below article rather interesting.

My theory, after looking at it, is: I'll defer to the Sheldons and
Lennards and Peters of this world as to the criticality of torque
accuracy on bicycle fasteners, but will also presume that I'm going to
be more accurate (with proper use of a properly-calibrated torque
wrench, obtaining accurate torque values in the first place, and
appropriately lubricating the fasteners) than going by *my* decidedly
uncalibrated arm. YMMV.
----
http://www.unbrako.com/docs/Fastener%20Facts.pdf
----
Quoting:

METHODS for CONTROLLING TIGHTNESS
Six methods can be used to control tightness of a threaded fastener.
In order of increasing accuracy - and increasing cost - they are:

Method Accuracy Relative Costs
Feel +/-35% 1
Torque wrench +/-25% 1-1/2
Turn-of-the-nut +/-15% 3
PLI washers +/-10% 7
Bolt elongation +/-3-5% 15
Strain gages +/-1% 20

But this table only tells part of the story. The less the accuracy of
the tightening method the greater must be the minimum yield strength
of the fastener in order to compensate for preload variations and to
insure a minimum clamping force. This can be done only be using a
fastener material of greater strength or increasing fastener size -
both of which will increase the cost of the fastener.

The decision as to which tightening method to use depends primarily on
the criticality of the joint. Generally, the more critical the joint
the more need for higher tightening accuracy and the greater the cost
for obtaining the right clamping force. It should always be noted that
the method selected will almost always lie between the two extremes,
for few applications will allow the high inaccuracy of the "feel"
method, while the high cost, highly accurate strain gages are used
almost entirely in the laboratory. The other methods
may be summarized as follows:

TORQUE WRENCH

This is the least expensive of the accepted methods of controlling
fastener preload but is the least accurate, chiefly because the
reading on dial is affected by the friction to be overcome.

TURN-OF-THE-NUT

In this method, the nut or bolt is turned a predetermined number of
degrees after all play has been removed from the joint.
How much to turn the nut or bolt cannot be calculated (because of the
"rubberiness" of the joint) but must be developed by tests for each
joint. It eliminates the friction factor; however, its accuracy is
affected by the care of the workman in measuring the angle the
nut or bolt is turned.

PRELOAD INDICATING WASHERS

Preload indicating (PLI) washers utilize compression of an inner ring
between two flat washers with an outer indicating washer for control.
As the load increases, the inner ring, which is higher than the outer
one, is squeezed down and enlarged in diameter until the
outer washer binds against two flat washers. When the inner ring has
been flattened to this point, the correct clamping force has been
reached. The PLI washer is sensitive only to axial load.

BOLT ELONGATION

In this method, a bolt from the lot is loaded in a tensile machine
with the same nut as used in the application. The distance from the
nut face to the underside of the bolt head is measured, and a plot is
made of bolt elongation in relation to induced load. In the
application, the fastener is tightened and the bolt elongation is
measured until the required preload as determined from the plot has
been achieved.

--
Live simply so that others may simply live

Qui si parla Campagnolo said:

I never said I needed to make roadside repairs. I have not needed any
tool except for a phillips head for a loose cleat for over 15 years of
riding. I carry no tools of any kind, never had, never needed them. Not
even a patch kit or tire lever, since I use tubulars.

I can't remember the last time I needed to make a field repair either --
that is, on my own bike -- beyond changing a tube. But I have used my
tool kit (an all-in-one thing), plus spare tire, boot material, and chain
"super-link", as well as clueless patches, zipties, and electrical tape.
I have used all of these helping other folks.

--

David L. Johnson

__o | Enron's slogan: Respect, Communication, Integrity, and
_`\(,_ | Excellence.
(_)/ (_) |

Qui si parla Campagnolo said:

I never said I needed to make roadside repairs. I have not needed any
tool except for a phillips head for a loose cleat for over 15 years of
riding. I carry no tools of any kind, never had, never needed them. Not
even a patch kit or tire lever, since I use tubulars.

I can't remember the last time I needed to make a field repair either --
that is, on my own bike -- beyond changing a tube. But I have used my
tool kit (an all-in-one thing), plus spare tire, boot material, and chain
"super-link", as well as clueless patches, zipties, and electrical tape.
I have used all of these helping other folks.

--

David L. Johnson

__o | Enron's slogan: Respect, Communication, Integrity, and
_`\(,_ | Excellence.
(_)/ (_) |

Qui si parla Campagnolo said:

I never said I needed to make roadside repairs. I have not needed any
tool except for a phillips head for a loose cleat for over 15 years of
riding. I carry no tools of any kind, never had, never needed them. Not
even a patch kit or tire lever, since I use tubulars.

I can't remember the last time I needed to make a field repair either --
that is, on my own bike -- beyond changing a tube. But I have used my
tool kit (an all-in-one thing), plus spare tire, boot material, and chain
"super-link", as well as clueless patches, zipties, and electrical tape.
I have used all of these helping other folks.

--

David L. Johnson

__o | Enron's slogan: Respect, Communication, Integrity, and
_`\(,_ | Excellence.
(_)/ (_) |

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

"Sheldon Brown" wrote: (clip) However, I don't know of any such gasketed
interfaces on bicycles.
^^^^^^^^^^^^^^^^^^
Sheldon, it isn't only gasketed connections that are tightened to specified
torques. Other examples would be con rod bearing caps, and wheel lug nuts.
The repair manual for an automobile gives the required torque where it is
required.

So, this would be a clue: are there any specified torques for bicycles?

Most new carbon parts will specify torque ranges to use when you install the
part on your bike.
-----------
Alex

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

"Sheldon Brown" wrote: (clip) However, I don't know of any such gasketed
interfaces on bicycles.
^^^^^^^^^^^^^^^^^^
Sheldon, it isn't only gasketed connections that are tightened to specified
torques. Other examples would be con rod bearing caps, and wheel lug nuts.
The repair manual for an automobile gives the required torque where it is
required.

So, this would be a clue: are there any specified torques for bicycles?

Most new carbon parts will specify torque ranges to use when you install the
part on your bike.
-----------
Alex

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

"Sheldon Brown" wrote: (clip) However, I don't know of any such gasketed
interfaces on bicycles.
^^^^^^^^^^^^^^^^^^
Sheldon, it isn't only gasketed connections that are tightened to specified
torques. Other examples would be con rod bearing caps, and wheel lug nuts.
The repair manual for an automobile gives the required torque where it is
required.

So, this would be a clue: are there any specified torques for bicycles?

Most new carbon parts will specify torque ranges to use when you install the
part on your bike.
-----------
Alex

"David L. Johnson" wrote: (clip)as well as clueless patches, (clip)
^^^^^^^^^^^^^^^
Is this an opinion or a typo?

"David L. Johnson" wrote: (clip)as well as clueless patches, (clip)
^^^^^^^^^^^^^^^
Is this an opinion or a typo?

"David L. Johnson" wrote: (clip)as well as clueless patches, (clip)
^^^^^^^^^^^^^^^
Is this an opinion or a typo?

I'd tend agree with you Neil, perhaps the confidence I gain from using a
(possibly not terribly accurate) torque wrench is illusory and perhaps the
criticality of accurate torque is less than I assume but the fact remains
that I, personally, feel more comfortable having something other than my own
unskilled 'feel' to gauge accuracy by. I can't help feeling that, for me at
least, a torque wrench is going to be by far the most accurate way of doing
things.

In any event it has turned out to be an interesting thread!

"Neil Brooks" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Sheldon Brown said:

Peter Chisholm said:

>
>>I'm a bike mechanic, not a car mechanic but every decent, non-car
>>dealer' wrench I have ever talked to uses a torque wrench on things
>>like drive train bolts and head bolts. IT is NOT a rudimentary part of
>>mechanical skill. It is the lazy mechanic that doesn't take the few
>>extra seconds to use a torque wrnch instead of just a 'wrench'. The
>>difference between a good mechanic and a great one.

I replied:

Quoted message said:

>Yes, I've long maintained that torque wrenches are automotive tools.
>
>I'm not sure what you mean by "drive train bolts" but certainly it is
>proper to use a torque wrench on head bolts or other applications that
>rely on gaskets getting crushed just the right amount.
>
>However, I don't know of any such gasketed interfaces on bicycles.

Peter responded:

Quoted message said:

You have long talked about no need for torque wrenches on a bicycle,
for things like crank bolts and I continue to not understand -why NOT
use one for crank bolts?

Because the numerical values are bogus, giving the illusion of precision.

Torque wrenches make sense in a production setting where all of the
bolts are from the same batch and all have the same degree of
cleanliness and lubrication.

However, even in these cases using standard torque settings for crank
fixing bolts is only a rough approximation.

I contend that the left crank needs to be tigthened harder than the
right one, so to me if you use the same rote torque value on both sides
you'll either be undertightening the left or overtightening the right.

Fortunately, there's enough leeway that you can usually get away with
this, but it is not optimal.

Quoted message said:

As for drivetrain, I woud hope the dude putting my driveshaft/rear
end/pinion gears back together on my truck uses a torque wrench..no
gaskets involved, just important things like the drive shaft.

The bicycle parts that are of equal criticality with those are the brake
cable anchor bolts and the bolts that secure the stem to the steerer.
Do you use a torque wrench on these?

Sheldon "Has Never Needed A Torque Wrench" Brown

To Sheldon's point, if the left crank needs to be tightened harder
than the right one, following a rote torque value certainly /would
result in a deviation from optimal. I'm just not resigned to the idea
that this deviation would be greater than the deviation resulting from
your average person torquing the same cranks by feel alone.

I found the below article rather interesting.

My theory, after looking at it, is: I'll defer to the Sheldons and
Lennards and Peters of this world as to the criticality of torque
accuracy on bicycle fasteners, but will also presume that I'm going to
be more accurate (with proper use of a properly-calibrated torque
wrench, obtaining accurate torque values in the first place, and
appropriately lubricating the fasteners) than going by *my* decidedly
uncalibrated arm. YMMV.
----
http://www.unbrako.com/docs/Fastener%20Facts.pdf
----
Quoting:

METHODS for CONTROLLING TIGHTNESS
Six methods can be used to control tightness of a threaded fastener.
In order of increasing accuracy - and increasing cost - they are:

Method Accuracy Relative Costs
Feel +/-35% 1
Torque wrench +/-25% 1-1/2
Turn-of-the-nut +/-15% 3
PLI washers +/-10% 7
Bolt elongation +/-3-5% 15
Strain gages +/-1% 20

But this table only tells part of the story. The less the accuracy of
the tightening method the greater must be the minimum yield strength
of the fastener in order to compensate for preload variations and to
insure a minimum clamping force. This can be done only be using a
fastener material of greater strength or increasing fastener size -
both of which will increase the cost of the fastener.

The decision as to which tightening method to use depends primarily on
the criticality of the joint. Generally, the more critical the joint
the more need for higher tightening accuracy and the greater the cost
for obtaining the right clamping force. It should always be noted that
the method selected will almost always lie between the two extremes,
for few applications will allow the high inaccuracy of the "feel"
method, while the high cost, highly accurate strain gages are used
almost entirely in the laboratory. The other methods
may be summarized as follows:

TORQUE WRENCH

This is the least expensive of the accepted methods of controlling
fastener preload but is the least accurate, chiefly because the
reading on dial is affected by the friction to be overcome.

TURN-OF-THE-NUT

In this method, the nut or bolt is turned a predetermined number of
degrees after all play has been removed from the joint.
How much to turn the nut or bolt cannot be calculated (because of the
"rubberiness" of the joint) but must be developed by tests for each
joint. It eliminates the friction factor; however, its accuracy is
affected by the care of the workman in measuring the angle the
nut or bolt is turned.

PRELOAD INDICATING WASHERS

Preload indicating (PLI) washers utilize compression of an inner ring
between two flat washers with an outer indicating washer for control.
As the load increases, the inner ring, which is higher than the outer
one, is squeezed down and enlarged in diameter until the
outer washer binds against two flat washers. When the inner ring has
been flattened to this point, the correct clamping force has been
reached. The PLI washer is sensitive only to axial load.

BOLT ELONGATION

In this method, a bolt from the lot is loaded in a tensile machine
with the same nut as used in the application. The distance from the
nut face to the underside of the bolt head is measured, and a plot is
made of bolt elongation in relation to induced load. In the
application, the fastener is tightened and the bolt elongation is
measured until the required preload as determined from the plot has
been achieved.

--
Live simply so that others may simply live

Quoted message said:

The bicycle parts that are of equal criticality with those are the
brake cable anchor bolts

I discover the looseness of these on test rides on my own bike upon
approaching the first red light from high speed. Thank goodness for rear
brakes. I'm not sure why I don't learn. Sloppy work on one's own bike, I
guess. I've never forgotten to tighten everything on customer's bikes
though...

Quoted message said:

and the bolts that secure the stem to the steerer.

Sheldon, aren't you a proponent of leaving these less than fully tight, so
as to preserve the integrity of handlebars in a crash? Or am I thinking of
brake levers?

--
Phil, Squid-in-Training

Hi Neil,
I agree w/most of what you posted, but you did miss a couple of things.

1. There is another common method of tension control called (strangely
enough) "Tension Control Bolts" or "TC Bolts" which tighten from one
side only by means of smaller splines on the small end of the bolt &
turning the nut in the usual manor. Plus a groove between the splines &
bolt. The groove is at 70% of the bolt area. IIRC. The spline snaps off
at ~70% tension, again IIRC. Rather like the protection groove of the
main bolt of a rear derailleur.

2 Turn of Nut. The major problem, in my experience is over tightening
prior to the tensioning. I've also read at least one study citing this
problem.

3. No one has mentioned the most , to me anyway, frighteinig porblem of
trensioning bicycle bolts; Aluminium threads. Usually it's the female
threads, but sometime the male threads or both. In any case when Al
threads are involved, the need for control is great, due to the ease of
stripping.

My 2 cents, John

In article <fZ6af.573$6C.189@dukeread02>,
[email hidden] says...

Quoted message said:

I discover the looseness of these on test rides on my own bike upon
approaching the first red light from high speed. Thank goodness for rear
brakes. I'm not sure why I don't learn. Sloppy work on one's own bike, I
guess. I've never forgotten to tighten everything on customer's bikes
though...

You may never know...Is repeat business dropping off?

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

In article <fZ6af.573$6C.189@dukeread02>,
[email hidden] says...

Quoted message said:

I discover the looseness of these on test rides on my own bike upon
approaching the first red light from high speed. Thank goodness for rear
brakes. I'm not sure why I don't learn. Sloppy work on one's own bike, I
guess. I've never forgotten to tighten everything on customer's bikes
though...

You may never know...Is repeat business dropping off?

Sorry , above was tongue in cheek - not the right place for the tongue
while going through a red light.