Re: First flat in a looooong time

On Tue, 1 Apr 2025 17:16:16 -0500, AMuzi <am@yellowjersey.org> wrote:

On 4/1/2025 4:30 PM, Jeff Liebermann wrote:

On Tue, 1 Apr 2025 15:37:12 -0500, AMuzi <am@yellowjersey.org> wrote:
 

On 4/1/2025 3:02 PM, Jeff Liebermann wrote:

On Wed, 26 Mar 2025 22:01:05 -0400, Joy Beeson
<jbeeson@invalid.net.invalid> wrote:
>

Tuesday, 25 March 2025
>
On Saturday, I came out of Aldi to find my front tire flat.
>
On Monday, I walked to the Trailhouse and handed the wheel
to the mechanic with instructions to put in a new tube and
find out what had happened to the old one.
>
He showed me a crack at the base of the valve stem.   The
tube had died of old age!

>
Not old age, but more likely the effects of exposure to chlorine which
can harden and crack rubber.
>
Multiple articles on the effects of chlorine on rubber:
<https://www.google.com/search?q=chlorine%20damage%20rubber>
>
Thanks to water chlorination, all the rubber seals and faucet gaskets
in my house last about 25 years.  Over the years, I've seen a few
damaged rubber valve stems on cars and bicycles stored near clothes
washing and swimming pool chlorination machinery.  The bleach (sodium
hypochlorite) used in washing condenses on everything and eventually
hardens rubber compounds.
>
The good news is that it takes many years for the rubber to harden and
crack.  Viton(FKM) fluorocarbon rubber seals are a big improvement:
<https://www.marcorubber.com/chemical-compatibility/BLEACH%20SOLUTIONS>
I have NOT found any bicycle inner tubes or valve stems made from
Viton(FKM):
<https://www.google.com/search?q=%22Viton%22%20bicycle%20tire%20valve%20stems>
However, one can buy blue Viton (FKM) valve cores for about $2/ea:
<https://schrader-pacific.com/wp-content/uploads/Valve-Core.pdf>
>
>

>
While I don't doubt you regarding chlorine (and both ozone
and UV also degrade the rubber in our tires/tubes), the base
of a bicycle tube valve has absolutely minimal exposure.  A
mechanical cause (abrasion, rim liner issues, low pressure)
is much more probable.

 
Ok, I yield to superior experience.  Mechanical cause is probably a
more likely explanation, but I have my doubts.  The best I can offer
is one anecdote to reinforce my claim.
 
During the 1970's, I was acting manager for my father's 13 unit
apartment building in North Hollyweird.  Among my duties was
maintaining several washing machines and dryers.  They were located in
an enclosed underground garage along with parking for about 5 cars, 2
motorcycles and about 5 bicycles (including mine).  There were also
some overhead storage cabinets for noxious, toxic and dangerous things
the tenants didn't want inside the apartments.  Inside the cabinets, I
also stored two new in the box Nashbar inner tubes.  I didn't use
these tubes and took them with me when I moved to Pomona.  After about
3 years, I needed a tube and found that the valve stem had cracked in
several places.  I opened the other box and found that it had the same
problem.  I didn't think about any of this at the time and just bought
replacement inner tubes.
 
I later realized that the only valve stems that had cracked were those
near the laundry equipment and storage chemicals.  However, a had
another inner tube stuffed into my "stuff bag" that I carried under my
saddle.  There was no sign of any cracking.  It was the same vintage,
age and (Nashbar) type tube.  However, because I kept my stuff back in
the apartment, it hadn't been exposed to the laundry chemicals.
 
I have my doubts about mechanical causes.  I can see one tire low on
air, experiencing abrasion damage or have liner issues.  However,
these problems would probably affect only one wheel, not both.

Right, even in a box it has more exposure than under a tire,
inside a rim, with no ambient air contacting the tube.

I'm not sure but, I don't think that the hardening of rubber requires
oxygen or air flow.  In the case of the washing machines, it was a
fairly high humidity from the washing machinery, which would condense
on literally everything.  The box is CUK (coated unbleached kraft)
paperboard.
<https://paperbox.org/4-types-of-paperboard/>

I found a few Nashbar inner tubes in boxes.
<https://photos.app.goo.gl/xuEqxJCiD9Dv4CfLA>
I'm don't have any Schrader valve types, such as the ones that failed,
so a Presta valve should suffice for a photo.  There was enough of a
gap in the end flaps to admit some (moist) air.  The date code on the
box was Nov 17, 2010.  These were obviously not form the original lot
of inner tubes from the 1970's.  Nashbar was founded in 1974.

Regarding local contamination, we once received a complaint
from a customer about his new tubulars whose tread was
cracked in an alligator skin pattern. We replaced them but
had no idea what was happening. The replacements did the
same thing.
>
As it turns out he had only recently refurbished his old
bike, bought our tires and started riding to work. He found
a convenient parking spot near a huge electric motor, a
plentiful ozone source.

Nice.  I've never seen the results of ozone exposure.  Ozone (O3) is
1.65 times denser than air:
<https://absoluteozone.com/ozone-library/ozone-fact-sheet/>
It will therefore tend to sink towards the ground.  If the wheel was
mounted on the tire and positioned somewhere near the floor, there
might be a problem.  Ozone has a half life at room temperatures of
about 3 days before it breaks down to O2.  However, it has a fairly
high oxidation potential which means that it will rot rubber.

"What causes rubber to deteriorate?"
<https://www.martins-rubber.co.uk/blog/what-causes-rubber-to-deteriorate/>
"...the most common rubber deterioration causes are exposure to light,
oxygen (ozone) and heat."

Drivel:  If the "huge electric motor" produced ozone, it must have had
a commutator which produces the required sparks.  At the level
required to rot rubber with 40 hrs per week exposure, that must have
been either a genuinely huge electric motor, or a very defective
electric motor badly in need brush replacement and commutator
cleaning. 


--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558