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Torque Wrenches



 
 
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  #1  
Old February 15th 04, 04:39 PM
MSeries
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Default Torque Wrenches

Maybe I should ask this in rec.bicycles.tech, they are keen on torque-ing
there. Who uses a torque wrench for their bikes ? What sort is it ? For
years I haven't and had only few problems, my cranks came loose once ! but I
know I should do things in accordance with the manuals especially on my best
bike. Also I read on r.b.t that some one was getting a proper tool for the
Shimano self extracting crankset bolt cap, has anyone seen these for sale in
the UK ? How would one manage to tighten the cap to the correct torque (3-7
Nm) with what I imagine is simply a small pin spanner ? I reckon it wouldn't
really matter for this as it takes no stress in normal usage.

Opinions please.


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  #2  
Old February 15th 04, 04:54 PM
Simonb
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Default Torque Wrenches

I had the same thought this morning so checked my local Halfords and they
only have torque wrenchs for cars. There must be something similar for bikes
otherwise the manufacturers wouldn't specify tensions, unless they do it for
legal reasons. Maybe our bikes would last longer with the correct tensions,
nothing over-tightened, and nothing too loose?

Simon


  #3  
Old February 15th 04, 05:22 PM
Call me Bob
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Default Torque Wrenches

On Sun, 15 Feb 2004 15:39:26 -0000, "MSeries"
wrote:

Who uses a torque wrench for their bikes ? What sort is it ? For
years I haven't and had only few problems, my cranks came loose once ! but I
know I should do things in accordance with the manuals especially on my best
bike. Also I read on r.b.t that some one was getting a proper tool for the
Shimano self extracting crankset bolt cap, has anyone seen these for sale in
the UK ? How would one manage to tighten the cap to the correct torque (3-7
Nm) with what I imagine is simply a small pin spanner ? I reckon it wouldn't
really matter for this as it takes no stress in normal usage.


Whether or not you use a torque wrench may well depend on how good a
"feel" you have when tightening fasteners. If you are at all
mechanically/practically minded then you should be able to manage
perfectly well without one. The diameter of the thread and materials
involved should be your guide. You'll need to go easier with aluminium
than you would with steel for example.

By instinct, most people probably over tighten the size of fastener
you find on your bike, but the acceptable range in this kind of
application is fairly forgiving.

The specific example you asked about, of a cap tightened to between
3-7 NM, will feel very light to most people. It's barely more than a
pinch with your wrist, you certainly wouldn't want to apply any effort
with a spanner or ratchet.

If you enjoy mech'ing your bike or want to know that you are being
accurate then go ahead and buy a torque wrench, but whatever you do
buy a *proper* one. Don't go near the toy ones you'll find in places
like Argos, they are worse than useless and will likely be wildly
inaccurate.

Good quality torque tools needn't be expensive, probably the best
value option in the UK would be a Norbar wrench. Excellent quality and
very reliable. Something like the Norbar SL1 would be ideal for your
bike work, range of 8 - 54NM and only about £45 from a good tool
dealer.

Using a torque wrench for a while will educate your wrist, as it were,
so in the future you can be more confident when working without one.
--

"Bob"

'The people have spoken, the *******s'

Email address is spam trapped.
To reply directly remove the beverage.
  #4  
Old February 15th 04, 06:07 PM
Peter B
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Default Torque Wrenches


"Simonb" wrote in message
...
I had the same thought this morning so checked my local Halfords and they
only have torque wrenchs for cars. There must be something similar for

bikes
otherwise the manufacturers wouldn't specify tensions, unless they do it

for
legal reasons.


Go to:

http://www.cromwell.co.uk/static/pub...pages/1037.pdf

http://www.cromwell.co.uk/browse?page=11

Like what Bob said, SL1 £46.22 mail order, credit cards accepted. (No, I
don't work for Cromwell, they are a local company but not just for local
people).


Regards,
Pete


  #5  
Old February 15th 04, 06:45 PM
Just zis Guy, you know?
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Default Torque Wrenches

On Sun, 15 Feb 2004 15:39:26 -0000, "MSeries"
wrote in message
:

Who uses a torque wrench for their bikes ? What sort is it ?


url:http://www.sheldonbrown.com/tork-grip.html of course!

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

88% of helmet statistics are made up, 65% of them at the University of Washington.
  #6  
Old February 15th 04, 06:51 PM
Andy Dingley
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Default Torque Wrenches

On Sun, 15 Feb 2004 15:39:26 -0000, "MSeries"
wrote:

Maybe I should ask this in rec.bicycles.tech, they are keen on torque-ing
there. Who uses a torque wrench for their bikes ?


I do. I'm a bit of a torque obsessive (cars too)

My bike torque wrench is a 3/8" drive Sealey. Pretty cheap for a
torque wrench, I bought it because none of my car-sized torque
wrenches went low enough to do bike bits. I use it for cranks mainly
(which is admittedly rare).

What sees more use on the bike is a torque screwdriver - 1/4" drive,
but a screwdriver handle. Just like a torque wrench, but for the extra
low torques. These are essential if you're an aluminium bolt
lightweight fanatic, otherwise you'll shear things off on a regular
basis. I find it's useful for torquing up badly designed brake cantis
like the infamous Onza HO that lock solid if mis-torqued, and I mainly
use it for putting the steel Allens back in the extra-soft alloy of my
AMP girder fork. Stripping a thread in that thing is a nightmare to
repair.

--
Smert' spamionam
  #7  
Old February 15th 04, 07:24 PM
Pete Biggs
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Default Torque Wrenches

MSeries wrote:
Maybe I should ask this in rec.bicycles.tech, they are keen on
torque-ing there. Who uses a torque wrench for their bikes ? What
sort is it ?


I only feel the need for one on cranks (square taper jobs). In fact I
don't even own a TR, just borrow a car mechanics type*. These cranks are
more difficult to judge by feel than other fastenings on a bike, partly
because of the high torque, but mostly because you're not just simply
doing up a bolt but wedging something on. It does feel a bit different.
A lot of people (including pro mechanics) under-tighten cranks.
Proper use of a torque wrench should prevent this, and also
over-tightening of course.

Having said that, I did strip the steerer clamp threads on the first ahead
stem I used - didn't realise how little torque they required.

* which I understand are not reliably accurate at low torque

~PB


  #8  
Old February 15th 04, 07:38 PM
Paul - xxx
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Default Torque Wrenches

MSeries posted ...

Maybe I should ask this in rec.bicycles.tech, they are keen on
torque-ing there. Who uses a torque wrench for their bikes ? What
sort is it ? For years I haven't and had only few problems, my cranks
came loose once ! but I know I should do things in accordance with
the manuals especially on my best bike. Also I read on r.b.t that
some one was getting a proper tool for the Shimano self extracting
crankset bolt cap, has anyone seen these for sale in the UK ? How
would one manage to tighten the cap to the correct torque (3-7 Nm)
with what I imagine is simply a small pin spanner ? I reckon it
wouldn't really matter for this as it takes no stress in normal
usage.

Opinions please.


Having been a 'Torque Control Engineer' for Desoutter (they make power tools
and GR Electronic Torque Control systems) for a while of my working life,
and having worked on the Raleigh production line, well, the Dyna-Tech part
anyway, among many others, it was notable that the torque specs given by
most manufacturing companies are mainly for use in the factories using power
tools and not necessarily for home users to stick to. The torque
characteristics of a hand and power turned bolt are completely different and
use different torque values.

Most Torque specs are also, nowadays, a sop to the ligitious society in USA
and provide an extra level of 'get-out' insurance for component failure.

IMHO a small 'home' torque wrench, used intermittently and probably without
practice and under less than ideal conditions, can do more harm than good.
I never use a torque wrench nowadays, except when re-building the bottom end
of an engine, or other 'safety critical' component, like brake disc bolts
for instance. General bicycle maintenance is happily reliant upon 'feel'
and the correct sizes of spanner. One good reason for the differing lengths
of spanners for differing sizes of nuts is the amount of leverage (torque)
that can be transmitted.


--
Paul


  #9  
Old February 15th 04, 07:43 PM
Call me Bob
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Default Torque Wrenches

On Sun, 15 Feb 2004 18:24:06 -0000, "Pete Biggs"
wrote:

In fact I
don't even own a TR, just borrow a car mechanics type*.


* which I understand are not reliably accurate at low torque


The accuracy on all torque wrenches drop away as you approach the edge
of it's working range (either upper or lower).
--

"Bob"

'The people have spoken, the *******s'

Email address is spam trapped.
To reply directly remove the beverage.
  #10  
Old February 15th 04, 09:00 PM
Just zis Guy, you know?
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Default Torque Wrenches

On Sun, 15 Feb 2004 18:38:31 -0000, "Paul - xxx"
wrote in message
:

IMHO a small 'home' torque wrench, used intermittently and probably without
practice and under less than ideal conditions, can do more harm than good.


I think you are probably right - using Allen keys or spanners, which
tend to be shorter the smaller they are, means it's easy to feel the
point at which the fastener is tight. Tightening a 6mm bolt into
aluminium with a monstrous great torque wrench you will never feel the
thread go up and you won't feel it strip either.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

88% of helmet statistics are made up, 65% of them at the University of Washington.
 




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