Torque wrench for BBs

Paul Davis said:

I was wondering whether anyone might recommend a torque wrench for
fitting bottom brackets?

I believe that the cartridge body screws in from the drive side which
is a lefthand thread. The torque wrench that I have isn't reversible.
Are Halford wrenches reversible?

Also, do I really need a torque wrench for this job? Can the BB or BB
shell be damaged by being too loose? I'm pretty new to bike
maintainence and no good at guaging torque values by hand.

Unless you've got a very unusual cartridge BB (*), then just put it in, and
turn the spanner until it feels "fairly tight". I'd call that a moderate
push on an 8-10 inch spanner handle. Not a big heave (too tight), and not
finger tight (too loose).

You don't need a torque wrench for this job (+).

(* ie. not your usual Shimano / Campag off the shelf stuff )
(+ I've never used a torque wrench on a bicycle, inspite of owning two,
knowing how to use them and having a passing understanding of mechanical
engineering precision. I suppose there might be a use somewhere in a disc
brake assembly?) .

- Nigel

--
NC - Webmaster for http://www.2mm.org.uk/
Replies to newsgroup postings to the newsgroup please.

in message <[email hidden]>, Paul Davis

(') said:

I was wondering whether anyone might recommend a torque wrench for
fitting bottom brackets?

I believe that the cartridge body screws in from the drive side which
is a lefthand thread. The torque wrench that I have isn't reversible.
Are Halford wrenches reversible?

Also, do I really need a torque wrench for this job? Can the BB or BB
shell be damaged by being too loose? I'm pretty new to bike
maintainence and no good at guaging torque values by hand.

You don't need a torque wrench to put a bottom bracket in, nor to do
most other jobs in bicycle maintenance. Obviously, don't overtighten
things particularly where they are threaded into aluminium. A bit of
copper grease helps when you are putting steel parts into aluminium,
just to be sure you can get it out again. But otherwise, just use
common sense.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; "If I were a Microsoft Public Relations person, I would probably
;; be sobbing on a desk right now" -- Rob Miller, editor, /.

Paul Davis said:

I was wondering whether anyone might recommend a torque wrench for fitting
bottom brackets?

I believe that the cartridge body screws in from the drive side which is a
lefthand thread. The torque wrench that I have isn't reversible. Are Halford
wrenches reversible?

Also, do I really need a torque wrench for this job? Can the BB or BB shell
be damaged by being too loose? I'm pretty new to bike maintainence and no
good at guaging torque values by hand.

Just screw it in until it stops!

in message <[email hidden]>, Getronics [censored]

(') said:

"Zog The Undeniable" <[email hidden]> wrote in message
news:4116447e.0@entanet...

Quoted message said:

Just screw it in until it stops!

Problem is you really should tighten the cranks back on with a torque
wrench or you could have problems in a short while, clicking etc
resulting in wear.

You must be extraordinarily heavy handed with a spanner. I've never used
a torque wrench on a bike in my life, and never had any problems of the
sort.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

'graveyards are full of indispensable people'

"Zog The Undeniable" <[email hidden]> wrote in message
news:4116447e.0@entanet...

Quoted message said:

Paul Davis said:

I was wondering whether anyone might recommend a torque wrench for

fitting

Quoted message said:

Quoted message said:

bottom brackets?

I believe that the cartridge body screws in from the drive side which is

a

Quoted message said:

Quoted message said:

lefthand thread. The torque wrench that I have isn't reversible. Are

Halford

Quoted message said:

Quoted message said:

wrenches reversible?

Also, do I really need a torque wrench for this job? Can the BB or BB

shell

Quoted message said:

Quoted message said:

be damaged by being too loose? I'm pretty new to bike maintainence and

no

Quoted message said:

Quoted message said:

good at guaging torque values by hand.

Just screw it in until it stops!

Problem is you really should tighten the cranks back on with a torque wrench
or you could have problems in a short while, clicking etc resulting in wear.

KC

Paul Davis said:

I believe that the cartridge body screws in from the drive side which is a lefthand thread.

Correct, assuming your frame doesn't have an "Italian" or "French" bottom bracket shell (which is pretty unlikely, especially if the bike is fairly modern)

Paul Davis said:

I'm no good at guaging torque values by hand.

I think that says it pretty well. I wouldn't recommend you follow the advice of "just tighten it until it feels about right". Everyone's idea of what is right is different.
There are torque wrenches which work for LH and RH threads (such as the Park Tool ones) but I'm not suggesting you go out and buy one. If you have some spare biggish nuts and bolts, put the nut in a vice and tighten the bolt with the torque wrench until it reaches your target torque; repeat this several times until you get a reasonable feel for that torque value. Then do your bottom bracket to the same feel.

If you have manufacturer's data for your B/B, follow that otherwise 350in-lbs (40Nm) will do. If you are using Loctite on the threads you can use a lower torque than if you are using anti-seize compound, which needs a higher torque to prevent movement of the cup in the shell.

Ian

Simon Brooke said:

in message <[email hidden]>, Getronics [censored]
([email hidden]'😉 wrote:

Quoted message said:

Quoted message said:

Problem is you really should tighten the cranks back on with a torque
wrench or you could have problems in a short while, clicking etc
resulting in wear.

Quoted message said:

You must be extraordinarily heavy handed with a spanner. I've never
used a torque wrench on a bike in my life, and never had any problems
of the sort.

Or light handed, I guess KC might have meant.

It's perfectly reasonable to use a torque wrench for this particular job
unless one is already experienced enough to know when the cranks are
pushed on far enough by feel (or measuring?).

~PB

"Simon Brooke" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

in message <[email hidden]>, Getronics [censored]

(') said:

"Zog The Undeniable" <[email hidden]> wrote in message
news:4116447e.0@entanet...

Quoted message said:

Just screw it in until it stops!

Problem is you really should tighten the cranks back on with a torque
wrench or you could have problems in a short while, clicking etc
resulting in wear.

You must be extraordinarily heavy handed with a spanner. I've never used
a torque wrench on a bike in my life, and never had any problems of the
sort.

Likelihood is of under tightened crank bolts. Stripped threads are possible
if torque wrench settings are exceeded. Few people have a calibrated
forearm.
Crank bolts are the only place on a bike I see the need for a torque wrench.

KC

Quoted message said:

Unless you've got a very unusual cartridge BB (*), then just put it in, and
turn the spanner until it feels "fairly tight". I'd call that a moderate
push on an 8-10 inch spanner handle. Not a big heave (too tight), and not
finger tight (too loose).

I'd say that your vague description is a fairly good argument in
favour of the precision of a torque wrench. Especially since I don't
think that the correct figure of around 500 in-lb for a cartridge BB
(sorry, don't remember the Nm multiplier) equates to 50lb on a 10"
spanner, which I would not describe as "fairly tight" or "moderate"
(but maybe I am just feeble).

I always use torque wrenches (Park PW-3 & PW-4, sadly no longer
available) when working on my bikes. I am often surprised at how much
tighter or looser the manufacturers' recommended settings are than I
would have chosen by instinct alone.

--
Peter Headland

Quoted message said:

You don't need a torque wrench to put a bottom bracket in, nor to do
most other jobs in bicycle maintenance. Obviously, don't overtighten
things particularly where they are threaded into aluminium. A bit of
copper grease helps when you are putting steel parts into aluminium,
just to be sure you can get it out again. But otherwise, just use
common sense.

Cobblers! After much practice (and with probably some innate
aptitude), you have developed a "feel" for this. You choose to forget
all of that and describe your acquired skill as as "common sense"?

I'll bet that, if we checked your bikes, we would find you are well
outside the manufacturer's recommended torque on any number of the
fasteners to which you have applied your magical common sense.
Fortunately, these things tend to have a wide safety margin.

The OP claims to have no feel for judging these things. I don't call
it "common sense" to perform safety-critical work on a bicycle (not
the BB, but stuff like brake cable pinch bolts) if you have no feel
for too loose (so the cable slips and you lose your brakes at a
critical moment) or too tight (so the thread strips or the bolt breaks
and you lose your brakes at a critical moment).

--
Peter Headland

in message <[email hidden]>, Peter

Headland (') said:

Quoted message said:

You don't need a torque wrench to put a bottom bracket in, nor to do
most other jobs in bicycle maintenance. Obviously, don't overtighten
things particularly where they are threaded into aluminium. A bit of
copper grease helps when you are putting steel parts into aluminium,
just to be sure you can get it out again. But otherwise, just use
common sense.

Cobblers! After much practice (and with probably some innate
aptitude), you have developed a "feel" for this. You choose to forget
all of that and describe your acquired skill as as "common sense"?

It's common sense not to overtighten a thing that's screwed into
aluminium, for example. There's no 'skill' in that, beyond recognising
what metal something is made of.

Quoted message said:

I'll bet that, if we checked your bikes, we would find you are well
outside the manufacturer's recommended torque on any number of the
fasteners to which you have applied your magical common sense.

Certainly, I've no doubt of it.

Quoted message said:

Fortunately, these things tend to have a wide safety margin.

They do. Which makes using a torque wrench ridiculous overkill in most
cases. I've ridden bikes I've maintained for thirty-five years now, and
my bikes very rarely have mechanical problems.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

[ This .sig subject to change without notice ]

Simon Brooke said:

in message <[email hidden]>, Peter
Headland ([email hidden]'😉 wrote:

Quoted message said:

Quoted message said:

Cobblers! After much practice (and with probably some innate
aptitude), you have developed a "feel" for this. You choose to forget
all of that and describe your acquired skill as as "common sense"?

It's common sense not to overtighten a thing that's screwed into
aluminium, for example. There's no 'skill' in that, beyond recognising
what metal something is made of.

Common sense feeds from experience and knowledge. We are not born with
knowledge of what alumnium and steel threads can take. One way of finding
out is to make a mistake and strip a thread, the other is to use a torque
wrench. (I learnt by the former method).

With square-taper type cranks, there is skill in knowing how far cranks
are pressed on and how far on they should be. It's not just a simple case
of doing a bolt up with this particular high-torque job. You have to stop
before the bolt is *fully* tight, yet so much force is necessary to wedge
the cranks up the spindle that the bolt feels pretty tight well before the
job is completed.

However, I agree with.....

Quoted message said:

a torque wrench [is] ridiculous overkill in most cases.

~PB

Pete Biggs [email hidden] opined the following...

Quoted message said:

Common sense feeds from experience and knowledge. We are not born with
knowledge of what alumnium and steel threads can take. One way of finding
out is to make a mistake and strip a thread, the other is to use a torque
wrench. (I learnt by the former method).

With square-taper type cranks, there is skill in knowing how far cranks
are pressed on and how far on they should be. It's not just a simple case
of doing a bolt up with this particular high-torque job. You have to stop
before the bolt is *fully* tight, yet so much force is necessary to wedge
the cranks up the spindle that the bolt feels pretty tight well before the
job is completed.

While the above is indeed true, in over 10 years of personal bike
maintenance I have never used (Or had access to) a torque wrench, and
yet have never suffered a mechanical failure related to over / under-
tightening of a thread. I learnt most of it with the aid of the Haynes
manual and the standard tools available in my parents' garage.

Jon