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From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Milk As A Tire Sealant
Date: 9 Aug 1997 00:16:37 GMT

Jeff Napier writes:

> In response to another thread about the effectiveness of liquid tire
> sealants, I have heard that ordinary milk works well.  I haven't tried it
> myself, probably because of a story an old-timer related.

> Seems he and his brother, in the days when all common bicycles had
> fit tires, put milk in their bike inner tubes - lots of milk because
> they didn't know how much was enough. Months later, this fellow had
> a blowout, which sprayed lots of the stinkiest old milk imaginable
> all over him.

Sounds like the experience I had in 1976 and reported here on
wreck.bike.  When I was riding my last Clement tubulars, that had poor
stitch protectors that caused many pin hole leaks, my tires kept going
flat.  Knowing about the ability of the butterfat in milk to plug such
holes, I poured a few ounces of milk, from a dairy on the Klausen pass
in Switzerland, into my tire pump and pumped it into my tires.  This
solved my problem, but a few weeks later, back home, while riding to
Santa Cruz with a bunch of bikies sitting on my wheel, I had a rear
blowout and sprayed them with putrid milk, while I had a hard time
controlling the bike as it slid around on the flat tubular like ice.

This was my encounter with sealant and it taught me that Sealants are
about as slick as butter inside a tube.  You can try that by just
feeling the slipperiness of a tube that has the stuff inside.

Are you sure your tale didn't originate from my experience.  The event
sounds so similar.

Jobst Brandt      <jbrandt@hpl.hp.com>



From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: do kelvar belts stop flats?
Date: 5 Aug 1997 00:20:22 GMT

Ray Bowman writes:

> Why not use sealants instead?  They work better and have negligible effect
> on rolling resistance.  Solar car racers, who typically test the #%@$ out
> of their components, determined sealants to be the best choice among all
> flat protection schemes.

Sealants have another hazard that the makers of the stuff are
apparently not aware.  A slimy substance inside the tube will make a
bicycle uncontrollable in the event the tire goes flat from a cut,
something sealant will not block.  I have had the experience, and was
fortunate that it occurred on a straight road with almost no crown.  I
slid all over, controlling something as benign as a rear tire flat.
You might want to try how well an inner tube full of this stuff glides
sideways before committing yourself to it.

Jobst Brandt      <jbrandt@hpl.hp.com>


From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Tire sealers -- any good?
Date: 7 Aug 1997 16:16:26 GMT

Ray Bowman writes:

>> Sealants have another hazard that the makers of the stuff are
>> apparently not aware.  A slimy substance inside the tube will make
>> a bicycle uncontrollable in the event the tire goes flat from a
>> cut, something sealant will not block.  I have had the experience,
>> and was fortunate that it occurred on a straight road with almost
>> no crown.  I slid all over, controlling something as benign as a
>> rear tire flat.  You might want to try how well an inner tube full
>> of this stuff glides sideways before committing yourself to it.

> "uncontrollable"?  You did in fact control your bike.

You're trying too hard Ray.  As I said, it was a straight flat road
and I was all over the place trying to slow down as the thing
fishtailed around.  That to me, is out of control.  What do you want?

> "benign as a rear flat" ?  Flats at speed are NOT benign, for either
> wheel.

Back up a bit.  On a flat straight road a rear flat IS benign.  How
about not changing the context to suit your needs.

> "slid all over" ?  This implies that the sealant was lubricating a
> large area of the outside of your tire, which is extremely doubtful.

None of the juice came out.  To improve your visualization skills,
imagine an inner tube, wet with lubricant on the inside, lying on the
floor.  You step on it and fall on your ass because it slides like a
banana peel.  Get the picture.  This is the hazard and is what users
of sealants do not visualize.

> When rolling along on a flat bicycle tire, the tire typically (1)
> flops chaotically from side-to-side, if you are heading more-or-less
> straight, or (2) causes much sideways "walking", if you are turning
> or on a side slope.

So why are you telling me that?  I just explained that a tire can walk
sideways and that lubricant inside enhances this characteristic greatly.

> Actual sliding can occur, of course, the case of hard cornering or
> as the result of inaccurate steering motions.

You must be thinking of larger tires.  A bicycle 700-28 tire lies flat
and rolls stably down the road.  It can be easily ridden flat for many
miles.  I have had that opportunity, as have others.  There are
circumstances when this is the only option.

When I read your stuff, I see a guy at the keyboard making it up on
the fly, out of pure hypothetical considerations.  I notice no
commitment to a source for your claims.

> Any chaotic process is difficult to control; and if you repeated
> your flat under seemingly identical conditions, I think it highly
> likely that you would find variable results.  You are not justified
> in drawing dramatic conclusions from a one-time event that clearly
> has chaotic character.

The way you say that you seem to assume I have no experience with flat
tires, at high speed and otherwise.  I and my riding associates have
had plenty of flats with both tubulars and clinchers.  No statistical
experiments are necessary to prove conclusively that a tire with an
internally lubricated tube will slide uncontrollably when flat.  Once
is enough to show that, what is otherwise a benign event, becomes a
dangerous one with slime in the tube.  In my case, had there been any
passing cars, I would have been hit or crashed for lack of maneuvering
space.

> Further, your conclusions are brought into question by the physics
> involved.  Because the sideways excursions of the flat tire, with
> respect to the rim, are limited by, roughly, the tire width
> (otherwise the tire would leave the rim).  This limit is the same
> whether there is sealant in the tire or not.

That's what the static case might suggest, but with a rotating wheel,
a centered portion of tire is continually being brought to the road to
subsequently slide to the side.  I see you've never had a flat on a
motorcycle, where this effect is pretty good even without slime in the
tube.

Jobst Brandt      <jbrandt@hpl.hp.com>


 
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