Tightening crank bolts.

Paul Davis

The driveside crank arm on my bike seems to loosen frequently so I was
wondering whether a bit of thread locking compound might be in order.

The LBS regularly just tighens up the crank bolts to torque but I remember
reading against this somewhere, and that one should pull the cranks before
re-tighening the bolts. If I remember correctly the piece was talking about
square taper cranks. Is this correct and, if so, is it also applicable to
splined cranks? I have Deore Octalink cranks.

Can I simply remove the bolt, apply the thread lock and tighten or should I
pull the cranks first?

Sorry if this is basic stuff but I'm just beginning to do my own
maintainence.

With Warm Regards,
Paul.

jobst.brandt@stanfordalumni.org

Paul Davis writes:

> The driveside crank arm on my bike seems to loosen frequently so I
> was wondering whether a bit of thread locking compound might be in
> order.

> The LBS regularly just tighens up the crank bolts to torque but I
> remember reading against this somewhere, and that one should pull
> the cranks before re-tighening the bolts. If I remember correctly
> the piece was talking about square taper cranks. Is this correct
> and, if so, is it also applicable to splined cranks? I have Deore
> Octalink cranks.

> Can I simply remove the bolt, apply the thread lock and tighten or
> should I pull the cranks first?

> Sorry if this is basic stuff but I'm just beginning to do my own
> maintainence.

http://draco.acs.uci.edu/rbfaq/FAQ/8f.11.html

Jobst Brandt
jobst.brandt@stanfordalumni.org

Zog The Undeniable

Paul Davis wrote:

> The driveside crank arm on my bike seems to loosen frequently so I was
> wondering whether a bit of thread locking compound might be in order.
>
> The LBS regularly just tighens up the crank bolts to torque but I remember
> reading against this somewhere, and that one should pull the cranks before
> re-tighening the bolts. If I remember correctly the piece was talking about
> square taper cranks. Is this correct and, if so, is it also applicable to
> splined cranks? I have Deore Octalink cranks.
>
> Can I simply remove the bolt, apply the thread lock and tighten or should I
> pull the cranks first?

I would personally tighten once, remove the bolts (but not pull the
cranks) then retighten with thread lock. "Virgin" threads are usually
too rough for thread lock to work properly.

After that, leave well alone unless you have to remove the cranks to
replace them or the BB. Periodic retightening may cause cranks to
break, although personally I've only ever seen them snap at the pedal
threads.

Paul Kopit

On Wed, 14 Apr 2004 20:02:42 +0000 (UTC), "Paul Davis"
<pjay.davis@btopenworld.com> wrote:

>The driveside crank arm on my bike seems to loosen frequently so I was
>wondering whether a bit of thread locking compound might be in order.

If the arm is actually getting loose each time, the crankarm is toast.
If the bolt is not to torque after some use, that's normal and should
not be retorqued. If you do that, you risk splitting the crankarm or
ruining the taper.

Werehatrack

On Wed, 14 Apr 2004 22:28:56 GMT, Paul Kopit <p.kopit@SPAMverizon.net>
may have said:

>On Wed, 14 Apr 2004 20:02:42 +0000 (UTC), "Paul Davis"
><pjay.davis@btopenworld.com> wrote:
>
>>The driveside crank arm on my bike seems to loosen frequently so I was
>>wondering whether a bit of thread locking compound might be in order.
>
>If the arm is actually getting loose each time, the crankarm is toast.
>If the bolt is not to torque after some use, that's normal and should
>not be retorqued. If you do that, you risk splitting the crankarm or
>ruining the taper.

It's an ISIS.


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Typoes are not a bug, they're a feature.
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Qui si parla Campagnolo

pjay-<< The driveside crank arm on my bike seems to loosen frequently so I was
wondering whether a bit of thread locking compound might be in order.
>><BR><BR>

If it loosens it means it was damaged the first time it loosened and cannot
generally be tightened anymore to stay tight. it was installed improperly the
FIRST time and then was damaged. Properly installed cranks DO NOT lossen.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Werehatrack

On Thu, 15 Apr 2004 02:15:30 GMT, Werehatrack
<rault00@earthWEEDSlink.net> may have said:

>On Wed, 14 Apr 2004 22:28:56 GMT, Paul Kopit <p.kopit@SPAMverizon.net>
>may have said:
>
>It's an ISIS.

Revision: Octalink. Still not tapered, though.


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My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Werehatrack

On Wed, 14 Apr 2004 20:02:42 +0000 (UTC), "Paul Davis"
<pjay.davis@btopenworld.com> may have said:

>The driveside crank arm on my bike seems to loosen frequently so I was
>wondering whether a bit of thread locking compound might be in order.

From what you describe below, I don't think it's going to solve the
problem.

>... I have Deore Octalink cranks.
>
>Can I simply remove the bolt, apply the thread lock and tighten or should I
>pull the cranks first?

If an Octalink keeps loosening, then the spline in the crank has
almost certainly already been damaged. For the long term, if that's
the case, you need a new left crank, and for the sake of safety, I'd
replace the BB as well. At this point, you don't know if the crank
wallowed because of improper installation (most likely cause), a
defect in the crank (not likely) or a problem in the BB shaft (such as
crud in the threads keeping the bolt from being properly tightened to
begin with). Unless you can positively affirm that the BB is not the
cause and/or has not been damaged in the interim, then swapping it out
makes sense to me. You're the one with the unit in front of you,
though, so it's your call to make.

In the meantime...

If you are going to replace the BB and crank both later, you may be
able to stretch the life of the current crank a bit by taking it off,
cleaning the splines and BB shaft (including the threads) thoroughly,
and reassembling...and intentionally overtightening the bolt. Some
people might try using epoxy to fill in the gaps in the spline, but
that's definitely not a long-term solution and might make the crank
very hard to get off later. In my opinion, if you want to try a
chemical-based stopgap fix, Loctite Bearing Mount would be the logical
choice to use in coating the splines. Be aware that you will need to
work *very fast* to install the bolt and get it torqued, and you do
not want to get that stuff on the bolt. It may set before you get the
bolt tight, thereby interfering with the torquing. Personally,
though, I think you need to just start shopping for a crank and stop
wasting time flogging a dead horse.



--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

John Everett

On Wed, 14 Apr 2004 20:36:14 GMT, jobst.brandt@stanfordalumni.org
wrote:

>Paul Davis writes:
>
>> The driveside crank arm on my bike seems to loosen frequently so I
>> was wondering whether a bit of thread locking compound might be in
>> order.
>
>> The LBS regularly just tighens up the crank bolts to torque but I
>> remember reading against this somewhere, and that one should pull
>> the cranks before re-tighening the bolts. If I remember correctly
>> the piece was talking about square taper cranks. Is this correct
>> and, if so, is it also applicable to splined cranks? I have Deore
>> Octalink cranks.
>
>> Can I simply remove the bolt, apply the thread lock and tighten or
>> should I pull the cranks first?
>
>> Sorry if this is basic stuff but I'm just beginning to do my own
>> maintainence.
>
>http://draco.acs.uci.edu/rbfaq/FAQ/8f.11.html

Nice treatise on square taper cranks, but that's not what he has.


jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3