Fitting cartridge BB - how to get it right

I'm trying to develop a feel for fitting cartridge bottom brackets
(Octalink). Shimano specs. state that both the cartridge and non-driveside
adapter should be torqued to between 50-70Nm.

Is it okay just to go for 'nice and tight' with both flanges up tight
against the BB shell or do I need to be more accurate than this? I
understand that a loose BB could damage the thread in the shell and I don't
want to risk this. Would a BB and/or adapter that were loose enough to cause
thread damage be obvious (creak or wobble) or is it more subtle than that?

PJay wrote:
I'm trying to develop a feel for fitting cartridge bottom brackets
(Octalink). Shimano specs. state that both the cartridge and non-driveside
adapter should be torqued to between 50-70Nm.

Is it okay just to go for 'nice and tight' with both flanges up tight
against the BB shell or do I need to be more accurate than this? I
understand that a loose BB could damage the thread in the shell and I don't
want to risk this. Would a BB and/or adapter that were loose enough to cause
thread damage be obvious (creak or wobble) or is it more subtle than that?


Just a suggestion here.
If you are reasonably good at things mechanical you can try to tighten
it yourself and see how it works. Once you hit the point where all
wiggle room disappears only apply a little more torque or you will be
killing your bearings.
If you are unsure of 'anything' then, before riding, figure out what Nm
converts to in foot pounds or something you can walk into an auto store
or LBS and buy the appropriate torque wrench.
Next check how much torque you have applied by your previous best guess
reasoning. You may find yourself dead on or way out in left field.
Remember, any doubts and you take it to a pro.
My 2 cents.
I like working on things when not riding, even if only to find out how
they work.
Best of luck.
Bill Baka

Thanks,

I've used a torque wrench in the past but when I mention it I'm often told
that you don't need a toruqe wrench or that I should learn to develop a
'feel'. Most of the maintenance books I've read just tend to suggest that it
needs to be done up tight. Shimano give a torque range of 50-70Nm which is
fairly wide.

I guess that my main concern is getting it too loose so that it could damage
the shell threads. Would a BB that was loose enough to do this be obvious
(wobbly and/or creaking)?

Thanks for taking the time to reply :-)
"Bill" wrote in message
et...
PJay wrote:
I'm trying to develop a feel for fitting cartridge bottom brackets
(Octalink). Shimano specs. state that both the cartridge and
non-driveside adapter should be torqued to between 50-70Nm.

Is it okay just to go for 'nice and tight' with both flanges up tight
against the BB shell or do I need to be more accurate than this? I
understand that a loose BB could damage the thread in the shell and I
don't want to risk this. Would a BB and/or adapter that were loose enough
to cause thread damage be obvious (creak or wobble) or is it more subtle
than that?
Just a suggestion here.
If you are reasonably good at things mechanical you can try to tighten it
yourself and see how it works. Once you hit the point where all wiggle
room disappears only apply a little more torque or you will be killing
your bearings.
If you are unsure of 'anything' then, before riding, figure out what Nm
converts to in foot pounds or something you can walk into an auto store or
LBS and buy the appropriate torque wrench.
Next check how much torque you have applied by your previous best guess
reasoning. You may find yourself dead on or way out in left field.
Remember, any doubts and you take it to a pro.
My 2 cents.
I like working on things when not riding, even if only to find out how
they work.
Best of luck.
Bill Baka

PJay wrote:
Thanks,

I've used a torque wrench in the past but when I mention it I'm often told
that you don't need a toruqe wrench or that I should learn to develop a
'feel'. Most of the maintenance books I've read just tend to suggest that it
needs to be done up tight. Shimano give a torque range of 50-70Nm which is
fairly wide.
Yes, but do you have a calibrated feel?

I guess that my main concern is getting it too loose so that it could damage
the shell threads. Would a BB that was loose enough to do this be obvious
(wobbly and/or creaking)?
I would think (no guarantees) that you would notice it well before
damage was done. I give the cranks a test before I ride. It's kind of
simple but effective. If you can grab both pedals and feel **any**
wiggle then you need to tighten things a bit. If the crank is hard to
turn then you need to loosen a bit. Eventually (I hope) you will develop
that 'feel'.
Bill Baka

Thanks for taking the time to reply :-)

On Sat, 5 May 2007 22:05:58 +0100, PJay wrote:

I'm trying to develop a feel for fitting cartridge bottom brackets
(Octalink). Shimano specs. state that both the cartridge and non-driveside
adapter should be torqued to between 50-70Nm.

Is it okay just to go for 'nice and tight' with both flanges up tight
against the BB shell or do I need to be more accurate than this? I
understand that a loose BB could damage the thread in the shell and I don't
want to risk this. Would a BB and/or adapter that were loose enough to cause
thread damage be obvious (creak or wobble) or is it more subtle than that?

At such high torque, it's pretty hard to do any damage by using maximum
force (but not jerking) on hand tools of reasonable size - I use a 30cm
wrench for this. I set the body snug against the shell, without tightening
it, then use max force on the lockring, then max force on the
cartridge again. Remember to clean and grease up the threads and
body/lockring interface first, since this gives your torque maximum
effectiveness, and makes disassembly easier later.


--
Home page: http://members.westnet.com.au/mvw

On Sun, 06 May 2007 03:48:07 GMT, Bill wrote:

If you are reasonably good at things mechanical you can try to tighten
it yourself and see how it works. Once you hit the point where all
wiggle room disappears only apply a little more torque or you will be
killing your bearings.

Bill, you don't appear to know what a cartridge is.

--
Home page: http://members.westnet.com.au/mvw

On Sun, 6 May 2007 21:13:40 +0100, PJay wrote:

I guess that my main concern is getting it too loose so that it could damage
the shell threads. Would a BB that was loose enough to do this be obvious
(wobbly and/or creaking)?

When a BB starts to loosen, it creaks when you apply extra force (i.e.
standing on the pedals). If you let it get bad, you'll be able to feel it
shift under the pressure, by which time it may well be doing
and/or suffering some damage.

--
Home page: http://members.westnet.com.au/mvw

Michael Warner wrote:
On Sun, 06 May 2007 03:48:07 GMT, Bill wrote:

If you are reasonably good at things mechanical you can try to tighten
it yourself and see how it works. Once you hit the point where all
wiggle room disappears only apply a little more torque or you will be
killing your bearings.

Bill, you don't appear to know what a cartridge is.

Pointer?
That was mostly general info for a beginning wrench artist.
Bill Baka

On Sun, 06 May 2007 22:31:17 GMT, Bill wrote:

That was mostly general info for a beginning wrench artist.

As opposed to a useful answer to the question.

Even though you may have completely misled the OP, I'm
sure he's gone away in awe of your mechanical skills, and
that's the important thing, isn't it?

--
Home page: http://members.westnet.com.au/mvw

Michael Warner wrote:
On Sun, 06 May 2007 22:31:17 GMT, Bill wrote:

That was mostly general info for a beginning wrench artist.

As opposed to a useful answer to the question.

Even though you may have completely misled the OP, I'm
sure he's gone away in awe of your mechanical skills, and
that's the important thing, isn't it?

Not really.
I can rebuild an automatic transmission pretty well though.
Bill