Newsgroups: rec.bicycles.misc
From: jbrandt@hpl.hp.com (Jobst Brandt)
Subject: Re: Extra presta valve parts with every tube
Date: Thu, 29 Feb 1996 18:50:30 GMT

Garry Lee writes:

> Sucking the air out of tubes COULD be hazardous, longterm.  Many
> tubes have powder in them, presumably talc.  Many such things induce
> a tissue reaction and you could be causing damage to your lungs long
> term.

Yes, and the moon might actually be made of green cheese.  So why did
you send me this posting as e-mail as if it were a private communication?

Having never flattened a tube by evacuation, you probably don't know
that one doesn't suck with the lungs, because it is ineffective.  All
the tubes I use contain talc, and so what.  The minuscule amount that
might get in my mouth is not unhealthy.

> Safer to roll the tubes up while pressing on the valve.  Americans
> inhale enough strange substances without adding tube powder!

Oh yes, danger lurks everywhere for believers in fables.  This dire
warning comes up here from time to time, showing that old saws never
die, they just get passed on from believer to believer.  However, if
you compare your "rolled up" tubes to a new one out of the package,
you'll find that there is a big difference between your spongy rolled
tube and an evacuated one.

Jobst Brandt      <jbrandt@hpl.hp.com> 

From: jobst.brandt@stanfordalumni.org
Subject: Re: twisted inner tube
Newsgroups: rec.bicycles.tech
Message-ID: <VrrN8.11710$3w2.54807@typhoon.sonic.net>
Date: Tue, 11 Jun 2002 18:37:41 GMT

Dave Kahn writes:

>> However, that's not how it is done.  Sucking by puckering the
>> cheeks gives many times more powerful suction than inhaling, which
>> is nearly useless in extracting air from an inner tube.  I think
>> your admonition "Obviously you've never tried it." is better suited
>> to your experience.

> Last time I tried this I failed miserably to get the tube flat. I'll
> have to have another go. What is the best way to keep the valve open
> while puckering?

There is a trick.  You must pull on the tube so that the tube wall
opposite the stem does not suck onto the stem hole and block exit of
gas, alternately pulling and sucking, and putting the finger on that
spot as a check valve.  There is method to this madness but it works
admirably.  Just rolling the tire up leaves plenty of air in the
radius at the sides of the flat section.

Jobst Brandt  <jobst.brandt@stanfordalumni.org>  Palo Alto CA