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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: First flat in a looooong time
Date: Tue, 1 Apr 2025 15:37:12 -0500
Organization: Yellow Jersey, Ltd.
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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.

-- 
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971