which torque wrench?

"Rob Morley" wrote in message
t...
In article
Clive George wrote:
"Rob Morley" wrote in message
t...
In article
Simon Brooke wrote:
in message ,
Anthony
Jones ') wrote:
snip
3) grease/don't grease the tapers (tried both).

Grease. Definitely.

You're kidding, aren't you?

Nope. Of course I imagine he's aware that this is a matter of some
debate,
which to me implies that either way works.

I've never seen any debate about it - who says the taper should be
greased?

Blimey, you've had your eyes shut a long time! :-)

Google groups for "grease crank taper" should give you a hint that there are
people on both sides of this argument.

cheers,
clive

Anthony Jones wrote:

[square taper cranks]

1) get it tighter (I've always tightened them to *really* tight,
honest).

How tight is "really tight" in Nm? If you don't know, maybe that's because
you didn't use a torque wrench, and maybe the cranks weren't really tight
enough.

~PB

Rob Morley wrote:

I've never seen any debate about it - who says the taper should be
greased?

Jobst Brandt - http://www.sheldonbrown.com/brandt/i...ng-cranks.html

I've had no problems whatsoever since doing this, although to be fair the
few before (a long time ago) might not have been anything to do with lack of
grease.

~PB

Simon Brooke wrote:
in message ,
Anthony Jones ') wrote:

1) get it tighter (I've always tightened them to *really* tight,
honest).

Don't.

Do!

Really tight is not needed. I have had cranks come loose -
twice in my life, I think - and this isn't good for them. But that's
in what must by now be getting on for quarter of a million miles.
Good and snug is all I ever do; I don't like to use force when doing
things up, because if you do, how will you undo them?

You're not just tightening a bolt. A good amount of force is needed to
wedge the cranks on the spindle properly. The hole in the aluminium crank
is designed to expand. The compression (combined with the bolt) is what
makes it work well.

Undoing is no problem with a long spanner or wrench, IME.

~PB

In article
Pete Biggs wrote:
Rob Morley wrote:

I've never seen any debate about it - who says the taper should be
greased?

Jobst Brandt - http://www.sheldonbrown.com/brandt/i...ng-cranks.html

I've had no problems whatsoever since doing this, although to be fair the
few before (a long time ago) might not have been anything to do with lack of
grease.

I've never had a problem with my own cranks loosening in over 25 years
of using square-taper cotterless cranks. After ten years in the bike
trade I'm only aware of one loosening problem with a crank I fitted -
that had grease on the taper. I've not seen any evidence of crank bolts
routinely working loose when properly tightened. I've never split a
crank. And I don't use dustcaps on my bikes, because they only trap
water. I wonder why JB has had such a different experience.

Pete Biggs wrote:
How tight is "really tight" in Nm? If you don't know, maybe that's because
you didn't use a torque wrench, and maybe the cranks weren't really tight
enough.

Since I'm obviously struggling to convince people, here's my full
unabridged story of square-taper woe complete with estimated torque
figures. Enjoy.

The first time it happened it was with a bike I bought complete, and I'd
never touched the cranks. After about 6 months of off-road riding,
something started creaking. Not being able to work out what it was, I
ignored it for a while, until I realised that the cranks were noticeably
floppy (not massively so: this was a mountain bike, and I could feel
them occasionally shift slightly if I'd been standing one foot forward,
and then I switched feet). So, I tightened them as tight as I could get
using all my weight and an allen key of similar length to the crank
itself. I make that about 65Nm (I weigh ~75kg, and half of my weight
would have been on the crank, half on the allen key). Which is a fair
bit tighter than the suggested torque, so I'd be surprised if that was
the problem.

The cranks were obviously mangled, because they'd just come loose again
within a couple of weeks of tightening. So I replaced them, and knowing
what could happen if they came loose, I tightened the new cranks as
tight as I could possibly get them. Again, they started making the
distinctive creak after a few months, but this time I knew to re-tighten
them immediately. They continued on a cycle of a few months creak free,
followed by creaking, followed by immediate re-tightening.

I had to replace the second set of cranks, because I snapped one
(Shimano later recalled that model). Exactly the same
creaking-tightening cycle happened with the third set.

Then I managed to snap the chainstay/dropout weld on that frame, and I
treated myself to an entirely new bike (another MTB). Again, creaking
after a few months. Eventually I thought "I've had enough of this", and
bought a XT Hollowtech-2 crank. That must have been about 2 years ago,
and the Hollowtech-2 crank has been perfectly behaved since day one.

I've never tried square-taper on a road bike, since I got my road bike
shortly after giving up on square-taper completely.

So, that's 4 cranksets: 2 shop-tightened, and 2 tightened by me to
~65Nm, and all re-tightened numerous times (including removing to try
things such as greasing/degreasing the tapers and putting Loctite on the
crank bolt). All were mid-range Shimano MTB cranks (Alivio/STX level),
on Shimano UN-53/73 BBs. As I mentioned previously, nothing else on any
bike has given me any repeated trouble, so I'd like to think it's not
just that I'm completely mechanically inept.

Given that all these problems occurred on MTBs, and that I do admittedly
give my MTBs a fair bit of abuse, I suspect it's more likely a riding
style issue rather than an installation one. I also notice that Jobst
Brandt claims being goofy-footed (which I am) can be related to cranks
coming loose, although I've never quite understood why.

Anthony

Simon Brooke wrote:
I don't like to use force when doing things up,
because if you do, how will you undo them?

How would I undo the crank bolt? I'd just ride the bike around for a
bit, and my legs would magically loosen it.

I'd rather have to cut my cranks of with an angle grinder (when the BB
gives up) instead of re-tightening them all the time, but the cranks
evidently don't like that idea.

Anthony

Rob Morley wrote:
In article
Pete Biggs wrote:
Rob Morley wrote:

I've never seen any debate about it - who says the taper should be
greased?

Jobst Brandt -
http://www.sheldonbrown.com/brandt/i...ng-cranks.html

I've had no problems whatsoever since doing this, although to be
fair the few before (a long time ago) might not have been anything
to do with lack of grease.

I've never had a problem with my own cranks loosening in over 25 years
of using square-taper cotterless cranks. After ten years in the bike
trade I'm only aware of one loosening problem with a crank I fitted -
that had grease on the taper.

Which proves nothing, of course.

I've not seen any evidence of crank
bolts routinely working loose when properly tightened. I've never
split a crank. And I don't use dustcaps on my bikes, because they
only trap water. I wonder why JB has had such a different experience.

Maybe he rides his bikes in an unusual way??? Monster gears up mountains,
for a start.

Anyway, I think the grease question is a red herring. I'm not suggesting
that it is necessary, personally. The important thing is to make sure the
cranks are properly tight -- then they won't come loose whether grease was
used or not.

~PB

I wrote:
Anyway, I think the grease question is a red herring. I'm not
suggesting that it is necessary, personally. The important thing is
to make sure the cranks are properly tight -- then they won't come
loose whether grease was used or not.

.....except in Anthony's case! :-)

~PB

in message , Pete Biggs
c') wrote:

Simon Brooke wrote:
in message ,
Anthony Jones ') wrote:

1) get it tighter (I've always tightened them to *really* tight,
honest).

Don't.

Do!

Really tight is not needed. I have had cranks come loose -
twice in my life, I think - and this isn't good for them. But that's
in what must by now be getting on for quarter of a million miles.
Good and snug is all I ever do; I don't like to use force when doing
things up, because if you do, how will you undo them?

You're not just tightening a bolt. A good amount of force is needed to
wedge the cranks on the spindle properly. The hole in the aluminium
crank
is designed to expand. The compression (combined with the bolt) is
what makes it work well.

I know. But, if it ain't broke, don't fix it. As you know, the crank
tends to squirm up the taper in use anyway, so preloading it excessively
with the bolt is not necessary. And, in my opinion, one failure every
hundred thousand miles ain't broke.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; part time troll.