Torque wrenches

Sheldon Brown

Werehatrack wrote:

>>>Judgement comes with experience. What is to provide judgement for the
>>>inexperienced?
>>
I replied, in part:

>>That's a very old conundrum...there's no substitute for experience.
>
> No, really, there isn't, but I would rather have the inexperienced
> turned into the knowledgeable in fewer breakage steps. IMO, it is
> hardly reasonable to recommend that an amateur trust his own judgement
> in tightening things *that matter* when the use of a torque wrench
> would increase the chances of the result being close to right.

I believe bicyles should be user serviceable, and I don't believe in
discouraging people from fixing their bikes just because they don't own
some exotic specialized tool, when that tool is not needed.

Similarly, you'll never see me promoting the "necessity" of wearing
special clothing for cycling. I believe cycling should be a democratic
activity, and that nobody should be reluctant to ride a bike just
because they don't have some specialize clothing.

I was going to leave this repetitious thread alone, except when it got
into saying that mechanics like myself who don't find a torque wrench
necessary are either hacks or egomaniacs.

I've taught a great many people bicycle repair, hardly ever had any
problem with overtightened bottom brackets.

The usual error is to undertighten, and if you do that you discover it
because the crank loosens up, so you tighten it. That's how I learned
(not by breaking bolts...only once recall breaking a crank mounting
bolt, and I believe that was a defective one.)

> In my
> own case, long ago, after several dozen VW engine overhauls, I knew by
> feel when the torque wrench was going to click on the head studs and
> such, but I didn't start out knowing...and I'd have been pissed off as
> hell if I'd had to do every job over several times, buying some new
> bits on each iteration, just to find out what the right feel was.

I never denied that a torque wrench is nearly essential for doing a good
job of installing an automobile engine's cylinder head, and for other
applications involving multiple bolts with crushable gaskets, but this
application does not arise in the bicycle world.

Torque wrenches are, indeed, important _automotive_ tools.

If you can afford one and choose to go to the trouble of using one for
bicycle work, that's fine with me too, but don't tell me that _I_ (or
anybody else) _need_ a torque wrench to do a proper job on a bicycle.

> When I took up cycling, I had years of mechanic experience on other
> equipment...but I still had to find the places where things were
> critical on bikes,

The only such parts on a bicycle that I consider truly critical are the
brake cable anchor bolts (and I've never known anybody to use a torque
wrench on those) and the wheel attachment hardware.

Sheldon "I've Broken/Stripped A Few Anchor Bolts In My Time" Brown
+----------------------------------------+
| When I am grown to man's estate |
| I shall be very proud and great, |
| And tell the other girls and boys |
| Not to meddle with my toys. |
| -R. L. Stevenson |
+----------------------------------------+
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

G.T.

"Calvin Jones" <info@parktool.com> wrote in message
news:aeaee867.0404081022.20bc93e9@posting.google.com...
> (This is a general reply to the topic as it began.)
> >
> > There are different reasons for using a torque wrench. It must be
> > kept in mind, however, a torque wrench is only a tool, and will not
> > replace thinking. What a threaded fastener (nut & bolt) needs is an
> > adequate amount of tension, which is simply not-too-little and
> > not-too-much. This can be achieved by a truing the thread either by
> > hand or by a torque wrench. A torque wrench is then a measuring tool,
> > much like a spoke tensiometer, a tape measure, a caliper, or even a
> > tablespoon or measuring cup for a cook. You can make a great cake by
> > grabbing hands full of flour and pouring out the salt, but most people
> > would not want to purchase such a cake at their local grocery store.
> > A torque wrench, used correctly, makes a good mechanic better.
> > However, if basic knowledge is lacking, a torque wrench will not act
> > as "magic wand" making every component safe and secure.
> >
> > There is also a difference between working on your own bike, and
> > working professionally on other peoples bikes. Correct use of a
> > torque wrench is one more way a shop can stand fully behind its work.
> > A quick look at various bicycle forums will show that the creaking
> > bicycle is often an issue, making lack of torque knowledge wide
> > spread.
>
> The fact that torque wrenches have not had general use in the
> "industry" mean that we are simply behind, which should not be a
> surprise. Torque wrench use is not rocket science. There are now
> higher torque values commonly used.

The place that I really find a torque wrench helps me is where I was
overtightening in the past. Particularly on things like brake pad
fasteners. No, I never broke one so I didn't realize I was overtightening,
but many times the spacers were warped in a not so noticeable way.

Greg

ML

And I use my torque wrench on the stem bolt & wedge bolt. I had a wedge
bolt stripped on my TTT stem on my new bike by a mechanic at my favorite
shop. Took me a while to figure out why I couldn't get my stem out.
Let me tell you what a PITA it was getting that out.

Of course, I also use it on the BB & crank bolts too!

MOO,
Matt

G.T. wrote:
> "Calvin Jones" <info@parktool.com> wrote in message
> news:aeaee867.0404081022.20bc93e9@posting.google.com...
>
>>(This is a general reply to the topic as it began.)
>>
>>>There are different reasons for using a torque wrench. It must be
>>>kept in mind, however, a torque wrench is only a tool, and will not
>>>replace thinking. What a threaded fastener (nut & bolt) needs is an
>>>adequate amount of tension, which is simply not-too-little and
>>>not-too-much. This can be achieved by a truing the thread either by
>>>hand or by a torque wrench. A torque wrench is then a measuring tool,
>>>much like a spoke tensiometer, a tape measure, a caliper, or even a
>>>tablespoon or measuring cup for a cook. You can make a great cake by
>>>grabbing hands full of flour and pouring out the salt, but most people
>>>would not want to purchase such a cake at their local grocery store.
>>>A torque wrench, used correctly, makes a good mechanic better.
>>>However, if basic knowledge is lacking, a torque wrench will not act
>>>as "magic wand" making every component safe and secure.
>>>
>>>There is also a difference between working on your own bike, and
>>>working professionally on other peoples bikes. Correct use of a
>>>torque wrench is one more way a shop can stand fully behind its work.
>>>A quick look at various bicycle forums will show that the creaking
>>>bicycle is often an issue, making lack of torque knowledge wide
>>>spread.
>>
>>The fact that torque wrenches have not had general use in the
>>"industry" mean that we are simply behind, which should not be a
>>surprise. Torque wrench use is not rocket science. There are now
>>higher torque values commonly used.
>
>
> The place that I really find a torque wrench helps me is where I was
> overtightening in the past. Particularly on things like brake pad
> fasteners. No, I never broke one so I didn't realize I was overtightening,
> but many times the spacers were warped in a not so noticeable way.
>
> Greg
>
>

Qui si parla Campagnolo

Jeff-<< You're wrong but Maestro Brown rebuts you better than I can. >><BR><BR>

Yep, we two have had this discussion before. In my mind, it's like having a
13mm bolt to tighten and having a 13mm wrench and a cresent wrench. I choose
the 13mm wrench cuz it's a better tool. When I have to tighten a crank, I have
an 8mm allen and a simple, easy to find, cheap(not exotic at all-ala Sheldon)
beam torque wrench with an 8mm end on it, I use the torque wrench cuz it's a
better tool.

If ya don't use one fine and dandy. But you don't have 'calibrated hands'. You
tighten something, it doesn't break or fall off...it was correct. But if you
needed to find 12 ft-lbs or 28, with your hands, I doubt you consistently
could.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Gary Young

Sheldon Brown <CaptBike@sheldonbrown.com> wrote in message news:<407627FD.40002@sheldonbrown.com>...

<snip>
> I never denied that a torque wrench is nearly essential for doing a good
> job of installing an automobile engine's cylinder head, and for other
> applications involving multiple bolts with crushable gaskets, but this
> application does not arise in the bicycle world.
<snip>

It seems to me that I started hearing about torque wrenches being de
rigeur about the time carbon fiber became so popular. Given what I
hear about how damage to carbon fiber parts is not always evident and
how failure can be catastrophic, I'd probably get a torque wrench if I
used carbon fiber components. I prefer just to avoid carbon fiber.

Werehatrack

On Fri, 09 Apr 2004 00:35:09 -0400, Sheldon Brown
<CaptBike@sheldonbrown.com> may have said:

>The only such parts on a bicycle that I consider truly critical are the
>brake cable anchor bolts (and I've never known anybody to use a torque
>wrench on those)

Me neither, and I can't say that it would be an appropriate place to
even try.

>and the wheel attachment hardware.

Which, with skewers, is a non-issue in any event. And with a solid
axle (which, frankly, I personally prefer) it's still questionable
whether a torque wrench is useful for that task because of the
irregularity of the mounting surface.

It's interesting to note, if you haven't run into it, that in many
places on automotive engines now, the final tightening regime for
critical fasteners isn't based on turning torque, but on a sequence of
steps which ends with rotating the bolts from a "just snug"
intermediate condition through a specific angle to their final
position.

BTW, when it comes to overtorquing something, I'll relate that I came
across a used bike at a garage sale recently which exemplified the
inappropriate application of the Armstrong Approach to Torque[1]. It
was a cheap mtb with a threadless stem, and the steerer was *very*
stiff. Looking closely, I could see that the head of the remaining
original stem pinch bolt was wallowed, the replacement for the other
was of the wrong type and had been overtightened to the point where
the threads were pulled out, and the bolt in the top cap had been run
down until the cap was badly distorted. The seller said the bike was
"messed up", and wanted $10 for it. All things considered, for a
Walgoose-level unit with as many things futzed as that one had
visible, I decided that I'd pass.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Paul Davis

Hi, the Park torque wrenches are beam type. I've had mixed messages about
beam type torque wrenches, been warned off by some and recommended them by
others. The other type (that gives/clicks when the set torque is reached)
seem to be refered to as clickers.

The confusion over what is/isn't good was one of the reasons for posting
originally.

jeffbonny

So vecchio51@aol.com (Qui si parla Campagnolo ) says:

>Jeff-<< You're wrong but Maestro Brown rebuts you better than I can. >><BR><BR>
>
>Yep, we two have had this discussion before. In my mind, it's like having a
>13mm bolt to tighten and having a 13mm wrench and a cresent wrench. I choose
>the 13mm wrench cuz it's a better tool. When I have to tighten a crank, I have
>an 8mm allen and a simple, easy to find, cheap(not exotic at all-ala Sheldon)
>beam torque wrench with an 8mm end on it, I use the torque wrench cuz it's a
>better tool.
>
>If ya don't use one fine and dandy. But you don't have 'calibrated hands'. You
>tighten something, it doesn't break or fall off...it was correct. But if you
>needed to find 12 ft-lbs or 28, with your hands, I doubt you consistently
>could.
>

For tightening 8mm crank bolts I use the same 16" 1/2" drive socket
bar I used In the shop for years and I can find a specific number of
ft lbs more reliably than you believe and certainly always within the
tolerances required on bicycles. The longer the lever the more easy it
is to feel and apply smaller degree of torque and since this is a tool
I've been using for years I know what it does. Using an off the rack
4" 8mm allen wrench I probably could not be accurate often enough to
satisfy you I admit.

BTW I never said I had "calibrated" hands, just sensitive ones
attached as SB says to a brain. You seem to think that a torque wrench
is a cure for inexperience, incompetence or a hangover but it ain't.

jeffb

Chalo

The routine use of torque wrenches ignores the fact that not all
thread pairs of a given size will respond the same to a fixed torque
value.

Industrially, torque specs are typically given for clean dry threads,
even if the threads in question are supposed to be lubricated. Why?
Because clean dry threads offer the best hope of getting anything like
a consistent fastener tension for a given torque. You are supposed to
make all necessary measurements to obtain a similar fastener tension
with whatever grease you happen to be using-- not that anybody
actually does that, of course.

Lubricant on threads can reduce the necessary torque to reach a given
fastener tension by more than half. The specific amount varies widely
according to lubrication type and amount, tension range, thread pitch
angle, component surface finish, and other factors.

Likewise, the maximum tension a given thread pair can withstand
without damage is dependent on the specific materials, tolerances, and
thread depth of each part as well as their relationship to each other.
Tiny variations in fit clearance and pitch length can make a dramatic
difference in failure torque.

Using a torque wrench and a reference table without regard to issues
that affect the specific part in question is no better than an
experienced mechanic honking on it until it "feels tight enough". For
someone without mechanical experience, a torque wrench and reference
table can get an assembly in the ballpark of tolerable conditions, and
in the workplace it can provide serious ability to CYA. But let's be
frank about what it offers-- a close-order-of-magnitude level of
precision, functionally the same as a trained technician's judgment
call.

Chalo Colina

Qui si parla Campagnolo

jeff-<< You seem to think that a torque wrench
is a cure for inexperience, incompetence or a hangover but it ain't. >><BR><BR>

It's not a 'cure' for anything, just a better tool for the job.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

g.daniels

a bottom line hear is the intro to nuts and bolts approach via the
torque wrench essentially thinking or educational approach skirting
trilal and error when bolting the abarth's head down. yeahyeahyeah and
yawl did this and once screwed it up good.
so. ahem. if one who wonders about this stuff takes a handful of
various sizes and a board bolts the nuts up with
a. grease
a1. never anti seize
b. no grease
c. try rust
d.blue oem loctite
e. red loctites

at relevant torque levels
then yagotta idea.

but don't thro the wrench away
someday yawl have three beers and...

Tom Sherman

g.daniels wrote:

> a bottom line hear is the intro to nuts and bolts approach via the
> torque wrench essentially thinking or educational approach skirting
> trilal and error when bolting the abarth's head down....

Fiat or Simca?

--
Tom Sherman - Quad Cities (Illinois Side)

John Everett

On Thu, 08 Apr 2004 14:08:35 -0400, Sheldon Brown
<captbike@sheldonbrown.com> wrote:

>I don't advocate using a torque wrench on bicycles. It's primarily an
>automotive tool.

I'm sure you could have a lively debate on this point with an A&P (FAA
licensed Airframe and Powerplant mechanic). Torque wrenches are
appropriate tools for properly tightening any threaded fastener, from
the head bolts on Briggs & Stratton lawnmower engines to bypass valves
on commercial jets.

If the well trained human body could successfully reproduce a
mechanical function 100% of the time, professional bowlers would bowl
nothing but 300 games and NBA players would never miss a free throw.
We are variable creatures. Torque wrenches are not.


jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

A Muzi

> g.daniels wrote:
>> a bottom line hear is the intro to nuts and bolts approach via the
>> torque wrench essentially thinking or educational approach skirting
>> trilal and error when bolting the abarth's head down....

Tom Sherman wrote:
> Fiat or Simca?

Abarth was Colin Chapman's (Lotus) middle name.

(Simca gets my vote for worst car of all time - but I
haven't actually worked on a Trabant outdoors in a Wisconsin
winter)
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971