Torque wrench question

I'm still a bit unsure of myself around maintenance issues so I've been
using a torque wrench for a lot of bolts (hopefully one day I'll develop a
good feel for things without a torque wrench).

Certain tools (BB tool, cassette lockring tool) require a variety of
adapters/sockets to fit them to the wrench. For example the BB tool fits in
a fairly long socket I have. Does extending the tool part away from the
wrench affect torque or should it be just as accurate?

Regarding the BB, the general advice seems to be 'do it up nice and tight',
which I have done. There's no play when grabbing the cranks and trying to
move the BB, and I've ridden the bike reasonably hard with no sign of
movement or creaking from the BB area so I'm assuming that things are fine.
Are there any symptoms of too loose or too tight a BB I should be looking
out for?

Cheers,
PJay

"PJay" wrote:

Certain tools (BB tool, cassette lockring tool) require a variety of
adapters/sockets to fit them to the wrench. For example the BB tool fits
in a fairly long socket I have. Does extending the tool part away from the
wrench affect torque or should it be just as accurate?

Doesn't affect the torque. Torque is force times lever arm.

Regarding the BB, the general advice seems to be 'do it up nice and
tight', which I have done. There's no play when grabbing the cranks and
trying to move the BB, and I've ridden the bike reasonably hard with no
sign of movement or creaking from the BB area so I'm assuming that things
are fine. Are there any symptoms of too loose or too tight a BB I should
be looking out for?

By the time the crank gets loose, damage may have already occurred. It's
more common for a crank bolt to be under torqued than over torqued.

If you don't have a torque wrench, you can at least approximate the torque
by knowing the distance of from where you're applying the force (lever arm)
and approximating how many pounds of force you're applying (e.g., 10 lbs of
force and a 6" lever arm equals 5 ft-lbs).

Here are some common torque values for bikes:

http://www.faqs.org/faqs/bicycles-fa...ection-33.html

Art Harris

On Sun, 30 Oct 2005 10:27:44 +0000 (UTC), "PJay"
wrote:

I'm still a bit unsure of myself around maintenance issues so I've been
using a torque wrench for a lot of bolts (hopefully one day I'll develop a
good feel for things without a torque wrench).

Torque to failure and then back off a quarter turn. Works for me.

Jasper

On Sun, 30 Oct 2005 10:27:44 +0000 (UTC), "PJay"
wrote:

Certain tools (BB tool, cassette lockring tool) require a variety of
adapters/sockets to fit them to the wrench. For example the BB tool fits in
a fairly long socket I have. Does extending the tool part away from the
wrench affect torque or should it be just as accurate?

Torque is torque, which is just force times moment arm. Theoretically the
elasticity of the steel in the extending bits matters (especially on the
narrow bits), since part of the torque will be used to twist the tools
slightly, but I rather suspect that no bike part is going to be doing that
to any *significant* degree.

Jasper

PJay wrote:
I'm still a bit unsure of myself around maintenance issues so I've been
using a torque wrench for a lot of bolts (hopefully one day I'll develop a
good feel for things without a torque wrench).

People that work on other things, like cars, don't wish to develop a
'feel', why should you?


Certain tools (BB tool, cassette lockring tool) require a variety of
adapters/sockets to fit them to the wrench. For example the BB tool fits in
a fairly long socket I have. Does extending the tool part away from the
wrench affect torque or should it be just as accurate?

Regarding the BB, the general advice seems to be 'do it up nice and tight',
which I have done. There's no play when grabbing the cranks and trying to
move the BB, and I've ridden the bike reasonably hard with no sign of
movement or creaking from the BB area so I'm assuming that things are fine.
Are there any symptoms of too loose or too tight a BB I should be looking
out for?

Depends on the BB type. If it is a cup and ball BB, nice and tight'=it
is being killed as you ride it. For cart bearing type, tight is right.
If the crank is loose, via the BB spindle on a cart BB, something is
wrong.


Cheers,
PJay

Jasper Janssen wrote:

Torque is torque, which is just force times moment arm. Theoretically the
elasticity of the steel in the extending bits matters (especially on the
narrow bits), since part of the torque will be used to twist the tools
slightly, but I rather suspect that no bike part is going to be doing that
to any *significant* degree.

A socket (or an extension) twisting will not diminish
the torque at the bolt being tightened.

If you put a piece of foam rubber on top of your bathroom
scale before you stand on it, the scale's reading of your
weight won't be reduced. It's not like some of your weight is
used up by the foam and isn't also bearing down on the scale.

Tom Ace

Jasper Janssen writes:

Torque is torque, which is just force times moment arm. Theoretically the
elasticity of the steel in the extending bits matters (especially on the
narrow bits), since part of the torque will be used to twist the tools
slightly, but I rather suspect that no bike part is going to be doing that
to any *significant* degree.

Incorrect. No matter the amount of twist, the torque is not reduced.
The twisting merely raises the energy requirement (torque times
angle).

Joe

On Sun, 30 Oct 2005 10:27:44 +0000, PJay wrote:

Certain tools (BB tool, cassette lockring tool) require a variety of
adapters/sockets to fit them to the wrench. For example the BB tool fits in
a fairly long socket I have. Does extending the tool part away from the
wrench affect torque or should it be just as accurate?

It will be just as accurate.

--

David L. Johnson

__o | A mathematician is a machine for turning coffee into theorems.
_`\(,_ | -- Paul Erdos
(_)/ (_) |

On Sun, 30 Oct 2005 13:09:01 +0000, Jasper Janssen wrote:

On Sun, 30 Oct 2005 10:27:44 +0000 (UTC), "PJay"
wrote:

I'm still a bit unsure of myself around maintenance issues so I've been
using a torque wrench for a lot of bolts (hopefully one day I'll develop a
good feel for things without a torque wrench).

Torque to failure and then back off a quarter turn. Works for me.

But if the part failed, you sort of have to replace something, don't you?

--

David L. Johnson

__o | Deserves death! I daresay he does. Many that live deserve
_`\(,_ | death. And some that die deserve life. Can you give it to
(_)/ (_) | them? Then do not be too eager to deal out death in judgement.
-- J. R. R. Tolkein

On Sun, 30 Oct 2005 11:13:49 -0500, "David L. Johnson"
wrote:
On Sun, 30 Oct 2005 13:09:01 +0000, Jasper Janssen wrote:
On Sun, 30 Oct 2005 10:27:44 +0000 (UTC), "PJay"
wrote:

I'm still a bit unsure of myself around maintenance issues so I've been
using a torque wrench for a lot of bolts (hopefully one day I'll develop a
good feel for things without a torque wrench).

Torque to failure and then back off a quarter turn. Works for me.

But if the part failed, you sort of have to replace something, don't you?

Sort of.

Jasper