Newsgroups: rec.bicycles.tech
Subject: Re: Spoke lub defies laws of physics
From: <JONQC@CUNYVM.BITNET>
Date: Wednesday, 11 Nov 1992 23:02:17 EST
Organization: City University of New York/ University Computer Center


First, thanks to all of you who pointed to capillary action as the
culprit.  I would have remained totally baffled without your help.

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From: jbrandt@hplredHPL.HP.COM (Jobst Brandt)

>John Leong writes:
>
>> In the 80's, I switched to "official" spoke prep, which is much more
>> viscous and less easily effected by gravity, but it's still
>> happening!  When I'm not looking, the stuff oozes down the spoke in
>> the direction of the hub. [...]  I'm sure that there is a reasonable
>> explanation for this (just like there's an explanation for why
>> Italian bottom bracket fixed cups like to unscrew themselves).

When I said, "I switched to 'official' spoke prep", I did not mean
Wheelsmith Spoke Prep.  I am using something I bought a long time ago,
through Bike Nashbar, called "Greythumb - spoke nipple compound".  It's
grey, came without directions, has the consistency of lithium grease,
doesn't have the thread locking properties of the Wheelsmith stuff and
doesn't say what it's made of but I suspect that it is a silicon based
lubricant.  Before that, I was quite happy using oil (as suggested in
your book).  Around the mid 80's, DT spoke packaging suddenly began
specifying not to use petroleum based products on their spoke threads
and that's why I switched.

> If you choose your rim and spokes appropriately, you don't need
> anything to keep nipples from unscrewing.  I have seen a good book on
> the subject that explains that in detail.  I recommend it.

Thanks, I have read your book and I have never felt the need to use
any kind of thread locking treatment.

I use the Greythumb in place of oil as a lubricant to prevent "sticky
nipples" during wheelbuilding and it seems to work a bit better.  The
little 3 or 4 ounce jar that I bought for $3.69 has lasted me for more
than 2 dozen wheels and I still have more than half of it left.

> About BB cups unscrewing... That's called precession and, if the
> exercise doesn't embarrass you (as it did some who read this
> previously), you can demonstrate it by making a circle with one thumb
> and fore finger while rolling your other index finger around in the
> opening as if it were planetary gear.  The roll will precess in the
> opposite direction from the contact point.  This is also the effect
> that unscrews pedals if not threaded R-R and L-L.  I find it amazing
> that only Swiss and English BB's are properly threaded.  I have always
> used "English" threads for that reason.

I received a similar explanation of this phenomenon from another
respondent.  I'm sorry if my phrasing was a little ambiguous but I am
already familiar with why Italian fixed cups tend to unscrew
themselves (I read it in Bicycling).  I was just using that as an
example of something that doesn't seem to conform to common sense; like
phono cartridge/turntable skating (please don't send explanations of
this either).  However, it was probably good to explain it again for the
benefit of readers who may have been wondering.

John Leong
JON@QCVAXA.BITNET
JONQC@CUNYVM.CUNY.EDU
Newsgroups: rec.bicycles.tech