Our customer (active daily rider + audax for 50+ years)
reports chronic valve core problems. Tubes are 700-35~42 PV
with removable core. Michelin, Kenda, Schwalbe, store
brands, assorted. (some from us, most not) He is not nearby
but I've known him since I was a teenager.

He reports:
"Planet Bike floor pump. Pretty normal. Any pump, any valve
stuff happens and air is not going in, take off chuck, try
again. Usually that works. Take off chuck, valve core flies
across room, never to be seen again. Also happens when it
seems all has been normal, fully aired, ready to ride and
then whoosh.

I am tightening every valve on every new tire or tube.
Majority are not full tight as new. Some cores have what
looks like a coating of loctite, some don't. Threading
always looks fine, feels fine. Am tightening with a 4-inch
adjustable crescent wrench. Why couldn't they make the
invisible wrench flats same size as a spoke wrench?"

Doesn't make sense to me. Any suggestions out there?
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On 1/21/2023 12:10 PM, AMuzi wrote:
> Our customer (active daily rider + audax for 50+ years) reports chronic
> valve core problems.  Tubes are 700-35~42 PV with removable core.
> Michelin, Kenda, Schwalbe, store brands, assorted. (some from us, most
> not) He is not nearby but I've known him since I was a teenager.
>
> He reports:
> "Planet Bike floor pump. Pretty normal. Any pump, any valve stuff
> happens and air is not going in, take off chuck, try again. Usually that
> works. Take off chuck, valve core flies across room, never to be seen
> again. Also happens when it seems all has been normal, fully aired,
> ready to ride and then whoosh.
>
> I am tightening every valve on every new tire or tube. Majority are not
> full tight as new. Some cores have what looks like a coating of loctite,
> some don't. Threading always looks fine, feels fine. Am tightening with
> a 4-inch adjustable crescent wrench. Why couldn't they make the
> invisible wrench flats same size as a spoke wrench?"
>
>
> Doesn't make sense to me. Any suggestions out there?

Poltergeists?

--
- Frank Krygowski

On Saturday, January 21, 2023 at 6:10:18 PM UTC+1, AMuzi wrote:
> Our customer (active daily rider + audax for 50+ years)
> reports chronic valve core problems. Tubes are 700-35~42 PV
> with removable core. Michelin, Kenda, Schwalbe, store
> brands, assorted. (some from us, most not) He is not nearby
> but I've known him since I was a teenager.
>
> He reports:
> "Planet Bike floor pump. Pretty normal. Any pump, any valve
> stuff happens and air is not going in, take off chuck, try
> again. Usually that works. Take off chuck, valve core flies
> across room, never to be seen again. Also happens when it
> seems all has been normal, fully aired, ready to ride and
> then whoosh.
>
> I am tightening every valve on every new tire or tube.
> Majority are not full tight as new. Some cores have what
> looks like a coating of loctite, some don't. Threading
> always looks fine, feels fine. Am tightening with a 4-inch
> adjustable crescent wrench. Why couldn't they make the
> invisible wrench flats same size as a spoke wrench?"
>
>
> Doesn't make sense to me. Any suggestions out there?
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971

Some of the issues I also have. Valve cores loose when new leading to loss of air overnight. Schwalbe tubes came in the past with those litlle black plastic mini thingies to tighten the core. When installing a new tube I always tighten the core. Also see no air going in after putting on the chuck. Second try all is good. Strange. Never had a core flying across the garage. I use Schwalbe and continental tubes.

Lou

On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:

>Doesn't make sense to me. Any suggestions out there?

Presta core in a Woods (Dunlop) stem or the reverse? The Woods valves
are the same diameter as Presta valves and will fit (I've never tried
it).
<https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>

Do I get a prize if I'm right?

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

On 1/21/2023 1:12 PM, Jeff Liebermann wrote:
> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:
>
>> Doesn't make sense to me. Any suggestions out there?
>
> Presta core in a Woods (Dunlop) stem or the reverse? The Woods valves
> are the same diameter as Presta valves and will fit (I've never tried
> it).
> <https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>
>
> Do I get a prize if I'm right?
>
>

Sorry not even close. Dunlop/Woods valves OD is same as
Schrader 8mm. Core threads are close in diameter but
Dunlop/Woods are visibly much coarser thread:

http://www.yellowjersey.org/NUVALVE.JPG

Besides which you can't readily find Dunlop/Woods 700C tubes
here in USA.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Sat, 21 Jan 2023 13:50:13 -0600, AMuzi <am@yellowjersey.org> wrote:

>On 1/21/2023 1:12 PM, Jeff Liebermann wrote:
>> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:
>>
>>> Doesn't make sense to me. Any suggestions out there?
>>
>> Presta core in a Woods (Dunlop) stem or the reverse? The Woods valves
>> are the same diameter as Presta valves and will fit (I've never tried
>> it).
>> <https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>
>>
>> Do I get a prize if I'm right?

>Sorry not even close.

OK. No prize for my bad guess.

>Dunlop/Woods valves OD is same as
>Schrader 8mm. Core threads are close in diameter but
>Dunlop/Woods are visibly much coarser thread:
>http://www.yellowjersey.org/NUVALVE.JPG

If he's using removable Presta cores, he's probably also using
tubeless tires. Maybe some sealant leaked in the pump head?

If the core threads are of similar diameter, and someone used thread
locker to deal with a thread diameter and thread pitch mismatch, my
guess points to a mismatch between the removable core and the stem. I
don't know how much of a mismatch, but if he's using a 4 inch crescent
wrench to install the core, then he has enough torque available to
cross-thread it. Launching the core under pressure tells me that the
threads don't match or the core is held in place by a small number of
threads (turns).

I know he says that the "Threading always looks fine, feels fine" but
I'm suspicious. Did he check both the stem and the core for thread
damage?

If not cross-threading, maybe remove the thread locker goo with
solvent and check if the core is a loose or sloppy fit.

Also, ask him to count the number of turns necessary to tighten the
core in place. (I don't know the correct number of turns).

<https://en.wikipedia.org/wiki/Presta_valve#Threading>

>Besides which you can't readily find Dunlop/Woods 700C tubes
>here in USA.

True.

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

AMuzi <am@yellowjersey.org> wrote:
> Our customer (active daily rider + audax for 50+ years)
> reports chronic valve core problems. Tubes are 700-35~42 PV
> with removable core. Michelin, Kenda, Schwalbe, store
> brands, assorted. (some from us, most not) He is not nearby
> but I've known him since I was a teenager.
>
> He reports:
> "Planet Bike floor pump. Pretty normal. Any pump, any valve
> stuff happens and air is not going in, take off chuck, try
> again. Usually that works. Take off chuck, valve core flies
> across room, never to be seen again. Also happens when it
> seems all has been normal, fully aired, ready to ride and
> then whoosh.
>
> I am tightening every valve on every new tire or tube.
> Majority are not full tight as new. Some cores have what
> looks like a coating of loctite, some don't. Threading
> always looks fine, feels fine. Am tightening with a 4-inch
> adjustable crescent wrench. Why couldn't they make the
> invisible wrench flats same size as a spoke wrench?"
>
>
> Doesn't make sense to me. Any suggestions out there?

None though I avoid tubes with removable cores as well most of my mini
pumps unscrew the valve I found which could get tedious!

Hence using a mini pump that doesn’t screw to the valve on the bike with
tubless.!

Roger Merriman

On 1/21/2023 3:33 PM, Jeff Liebermann wrote:
> On Sat, 21 Jan 2023 13:50:13 -0600, AMuzi <am@yellowjersey.org> wrote:
>
>> On 1/21/2023 1:12 PM, Jeff Liebermann wrote:
>>> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:
>>>
>>>> Doesn't make sense to me. Any suggestions out there?
>>>
>>> Presta core in a Woods (Dunlop) stem or the reverse? The Woods valves
>>> are the same diameter as Presta valves and will fit (I've never tried
>>> it).
>>> <https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>
>>>
>>> Do I get a prize if I'm right?
>
>> Sorry not even close.
>
> OK. No prize for my bad guess.
>
>> Dunlop/Woods valves OD is same as
>> Schrader 8mm. Core threads are close in diameter but
>> Dunlop/Woods are visibly much coarser thread:
>> http://www.yellowjersey.org/NUVALVE.JPG
>
> If he's using removable Presta cores, he's probably also using
> tubeless tires. Maybe some sealant leaked in the pump head?
>
> If the core threads are of similar diameter, and someone used thread
> locker to deal with a thread diameter and thread pitch mismatch, my
> guess points to a mismatch between the removable core and the stem. I
> don't know how much of a mismatch, but if he's using a 4 inch crescent
> wrench to install the core, then he has enough torque available to
> cross-thread it. Launching the core under pressure tells me that the
> threads don't match or the core is held in place by a small number of
> threads (turns).
>
> I know he says that the "Threading always looks fine, feels fine" but
> I'm suspicious. Did he check both the stem and the core for thread
> damage?
>
> If not cross-threading, maybe remove the thread locker goo with
> solvent and check if the core is a loose or sloppy fit.
>
> Also, ask him to count the number of turns necessary to tighten the
> core in place. (I don't know the correct number of turns).
>
> <https://en.wikipedia.org/wiki/Presta_valve#Threading>
>
>> Besides which you can't readily find Dunlop/Woods 700C tubes
>> here in USA.
>
> True.
>

He runs regular tires with PV tubes on most bikes, tubulars
on a couple of them.

No tubeless.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Saturday, January 21, 2023 at 2:28:10 PM UTC-8, AMuzi wrote:
> On 1/21/2023 3:33 PM, Jeff Liebermann wrote:
> > On Sat, 21 Jan 2023 13:50:13 -0600, AMuzi <a...@yellowjersey.org> wrote:
> >
> >> On 1/21/2023 1:12 PM, Jeff Liebermann wrote:
> >>> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <a...@yellowjersey.org> wrote:
> >>>
> >>>> Doesn't make sense to me. Any suggestions out there?
> >>>
> >>> Presta core in a Woods (Dunlop) stem or the reverse? The Woods valves
> >>> are the same diameter as Presta valves and will fit (I've never tried
> >>> it).
> >>> <https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>
> >>>
> >>> Do I get a prize if I'm right?
> >
> >> Sorry not even close.
> >
> > OK. No prize for my bad guess.
> >
> >> Dunlop/Woods valves OD is same as
> >> Schrader 8mm. Core threads are close in diameter but
> >> Dunlop/Woods are visibly much coarser thread:
> >> http://www.yellowjersey.org/NUVALVE.JPG
> >
> > If he's using removable Presta cores, he's probably also using
> > tubeless tires. Maybe some sealant leaked in the pump head?
> >
> > If the core threads are of similar diameter, and someone used thread
> > locker to deal with a thread diameter and thread pitch mismatch, my
> > guess points to a mismatch between the removable core and the stem. I
> > don't know how much of a mismatch, but if he's using a 4 inch crescent
> > wrench to install the core, then he has enough torque available to
> > cross-thread it. Launching the core under pressure tells me that the
> > threads don't match or the core is held in place by a small number of
> > threads (turns).
> >
> > I know he says that the "Threading always looks fine, feels fine" but
> > I'm suspicious. Did he check both the stem and the core for thread
> > damage?
> >
> > If not cross-threading, maybe remove the thread locker goo with
> > solvent and check if the core is a loose or sloppy fit.
> >
> > Also, ask him to count the number of turns necessary to tighten the
> > core in place. (I don't know the correct number of turns).
> >
> > <https://en.wikipedia.org/wiki/Presta_valve#Threading>
> >
> >> Besides which you can't readily find Dunlop/Woods 700C tubes
> >> here in USA.
> >
> > True.
> >
> He runs regular tires with PV tubes on most bikes, tubulars
> on a couple of them.
>
> No tubeless.
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971
Park makes a blue anodized aluminum valve wrench which can righten the valve stem in so tightly that no pump can loosen it.

On 1/21/2023 5:28 PM, AMuzi wrote:
> On 1/21/2023 3:33 PM, Jeff Liebermann wrote:
>> On Sat, 21 Jan 2023 13:50:13 -0600, AMuzi <am@yellowjersey.org> wrote:
>>
>>> On 1/21/2023 1:12 PM, Jeff Liebermann wrote:
>>>> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:
>>>>
>>>>> Doesn't make sense to me. Any suggestions out there?
>>>>
>>>> Presta core in a Woods (Dunlop) stem or the reverse?  The Woods valves
>>>> are the same diameter as Presta valves and will fit (I've never tried
>>>> it).
>>>> <https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>
>>>>
>>>> Do I get a prize if I'm right?
>>
>>> Sorry not even close.
>>
>> OK.  No prize for my bad guess.
>>
>>> Dunlop/Woods valves OD is same as
>>> Schrader 8mm. Core threads are close in diameter but
>>> Dunlop/Woods are visibly much coarser thread:
>>> http://www.yellowjersey.org/NUVALVE.JPG
>>
>> If he's using removable Presta cores, he's probably also using
>> tubeless tires.  Maybe some sealant leaked in the pump head?
>>
>> If the core threads are of similar diameter, and someone used thread
>> locker to deal with a thread diameter and thread pitch mismatch, my
>> guess points to a mismatch between the removable core and the stem.  I
>> don't know how much of a mismatch, but if he's using a 4 inch crescent
>> wrench to install the core, then he has enough torque available to
>> cross-thread it.  Launching the core under pressure tells me that the
>> threads don't match or the core is held in place by a small number of
>> threads (turns).
>>
>> I know he says that the "Threading always looks fine, feels fine" but
>> I'm suspicious.  Did he check both the stem and the core for thread
>> damage?
>>
>> If not cross-threading, maybe remove the thread locker goo with
>> solvent and check if the core is a loose or sloppy fit.
>>
>> Also, ask him to count the number of turns necessary to tighten the
>> core in place.  (I don't know the correct number of turns).
>>
>> <https://en.wikipedia.org/wiki/Presta_valve#Threading>
>>
>>> Besides which you can't readily find Dunlop/Woods 700C tubes
>>> here in USA.
>>
>> True.
>>
>
> He runs regular tires with PV tubes on most bikes, tubulars on a couple
> of them.
>
> No tubeless.

To me, the most mysterious aspect is that it seems to happen repeatedly.
That suggests more of an operator problem than a manufacturing tolerance
problem, unless this is confined to one batch of tubes.

Could he be over-tightening things to the point threads are destroyed?

If not, I'm going with poltergeists.

--
- Frank Krygowski

Frank Krygowski wrote:
> On 1/21/2023 5:28 PM, AMuzi wrote:
>> On 1/21/2023 3:33 PM, Jeff Liebermann wrote:
>>>>> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:
>>>>>
>>>>>> Doesn't make sense to me. Any suggestions out there?

>>> Also, ask him to count the number of turns necessary to tighten the
>>> core in place.  (I don't know the correct number of turns).
>>>
>>> <https://en.wikipedia.org/wiki/Presta_valve#Threading>

>> He runs regular tires with PV tubes on most bikes, tubulars on a couple
>> of them.
>>
>> No tubeless.

> To me, the most mysterious aspect is that it seems to happen repeatedly.
> That suggests more of an operator problem than a manufacturing tolerance
> problem, unless this is confined to one batch of tubes.

Yup. The constant part in his experimentation is his wrench use.
(Unless you believe $EVILSTATE manipulated the settings of all the
manufacturers' valve core tightening robots.) I also stumbled across
"invisible wrench flats" -- might his reading glasses need an update?

> Could he be over-tightening things to the point threads are destroyed?

I'd explore "age-denial" and carefully find out if he's ready to convert
to "more robust" Schrader or a more comfy bike with wider tires that
work better with even lower pressure than his current setup. Don't be
the next guy selling him one more new pump & innertube that won't solve
the problem!

On Sat, 21 Jan 2023 16:28:06 -0600, AMuzi <am@yellowjersey.org> wrote:

>On 1/21/2023 3:33 PM, Jeff Liebermann wrote:
>> On Sat, 21 Jan 2023 13:50:13 -0600, AMuzi <am@yellowjersey.org> wrote:
>>
>>> On 1/21/2023 1:12 PM, Jeff Liebermann wrote:
>>>> On Sat, 21 Jan 2023 11:10:15 -0600, AMuzi <am@yellowjersey.org> wrote:
>>>>
>>>>> Doesn't make sense to me. Any suggestions out there?
>>>>
>>>> Presta core in a Woods (Dunlop) stem or the reverse? The Woods valves
>>>> are the same diameter as Presta valves and will fit (I've never tried
>>>> it).
>>>> <https://www.dutchbikeshop.co.uk/pump-tyres-dutch-bike>
>>>>
>>>> Do I get a prize if I'm right?
>>
>>> Sorry not even close.
>>
>> OK. No prize for my bad guess.
>>
>>> Dunlop/Woods valves OD is same as
>>> Schrader 8mm. Core threads are close in diameter but
>>> Dunlop/Woods are visibly much coarser thread:
>>> http://www.yellowjersey.org/NUVALVE.JPG
>>
>> If he's using removable Presta cores, he's probably also using
>> tubeless tires. Maybe some sealant leaked in the pump head?
>>
>> If the core threads are of similar diameter, and someone used thread
>> locker to deal with a thread diameter and thread pitch mismatch, my
>> guess points to a mismatch between the removable core and the stem. I
>> don't know how much of a mismatch, but if he's using a 4 inch crescent
>> wrench to install the core, then he has enough torque available to
>> cross-thread it. Launching the core under pressure tells me that the
>> threads don't match or the core is held in place by a small number of
>> threads (turns).
>>
>> I know he says that the "Threading always looks fine, feels fine" but
>> I'm suspicious. Did he check both the stem and the core for thread
>> damage?
>>
>> If not cross-threading, maybe remove the thread locker goo with
>> solvent and check if the core is a loose or sloppy fit.
>>
>> Also, ask him to count the number of turns necessary to tighten the
>> core in place. (I don't know the correct number of turns).
>>
>> <https://en.wikipedia.org/wiki/Presta_valve#Threading>
>>
>>> Besides which you can't readily find Dunlop/Woods 700C tubes
>>> here in USA.
>>
>> True.

>He runs regular tires with PV tubes on most bikes, tubulars
>on a couple of them.
>
>No tubeless.

If all his bicycles have the same problem (launching removable Presta
cores), then I suspect that it's something that all of them have in
common. Offhand, that would be the owner and the 4 inch crescent
wrench. There might also be an adapter involved that wasn't
mentioned. It's not the pump or pump head because it's very unlikely
to have more than one defective head. My guess(tm) is that he's
stripping out the threads with the wrench. I can't think of anything
else that would inspire a Presta core to go airborne. Unless he has a
borescope or endoscope to inspect the threads, I would suspect that
his visual inspection and "Threading always looks fine, feels fine"
observation might be incorrect. Check the threads. My guess(tm) is
that they are all stripped or a very loose fit.

I'm still interested in the number of turns he applied to insert the
Presta core. If it's less than perhaps 5 turns, it's easy to strip
the brass threads. On visual inspection, he might be looking at the
remaining threads, which will look normal. If my guess(tm) is
correct, only the first 5 threads will be stripped and the rest will
look fine. The minimum recommended thread engagement for brass is 1
to 1.5 times the threaded core diameter.

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

Jeff Liebermann wrote:
> On Sat, 21 Jan 2023 16:28:06 -0600, AMuzi wrote:

>> He runs regular tires with PV tubes on most bikes, tubulars
>> on a couple of them.
>>
>> No tubeless.
>
> If all his bicycles have the same problem (launching removable Presta
> cores), then I suspect that it's something that all of them have in
> common. Offhand, that would be the owner and the 4 inch crescent
> wrench. There might also be an adapter involved that wasn't
> mentioned. It's not the pump or pump head because it's very unlikely
> to have more than one defective head. My guess(tm) is that he's
> stripping out the threads with the wrench. I can't think of anything
> else that would inspire a Presta core to go airborne. Unless he has a
> borescope or endoscope to inspect the threads, I would suspect that
> his visual inspection and "Threading always looks fine, feels fine"
> observation might be incorrect. Check the threads. My guess(tm) is
> that they are all stripped or a very loose fit.

Are we dangerously nearing a premature, dangerously narrow "consensus"
about the most likely cause? So let me add another, far-out guess, instead:

How about corrosion aided by some basic rearragement in the customer's
parts/bike storage environment? Some unmentioned, but galvanically
furious exotic valve covers that a magically inclined, obsessive
customer puts on, first thing, whenever he gets new tubes?

On Sun, 22 Jan 2023 10:39:20 +0100, Sepp Ruf <inqbel@Safe-mail.net>
wrote:

>Jeff Liebermann wrote:
>> On Sat, 21 Jan 2023 16:28:06 -0600, AMuzi wrote:
>
>>> He runs regular tires with PV tubes on most bikes, tubulars
>>> on a couple of them.
>>>
>>> No tubeless.
>>
>> If all his bicycles have the same problem (launching removable Presta
>> cores), then I suspect that it's something that all of them have in
>> common. Offhand, that would be the owner and the 4 inch crescent
>> wrench. There might also be an adapter involved that wasn't
>> mentioned. It's not the pump or pump head because it's very unlikely
>> to have more than one defective head. My guess(tm) is that he's
>> stripping out the threads with the wrench. I can't think of anything
>> else that would inspire a Presta core to go airborne. Unless he has a
>> borescope or endoscope to inspect the threads, I would suspect that
>> his visual inspection and "Threading always looks fine, feels fine"
>> observation might be incorrect. Check the threads. My guess(tm) is
>> that they are all stripped or a very loose fit.

>Are we dangerously nearing a premature, dangerously narrow "consensus"
>about the most likely cause? So let me add another, far-out guess, instead:

I'll confess that I've never seen removable Presta core. Here's a
photo:
<https://www.lordgun.com/presta-removable-valve-core-2>
<https://www.tradeinn.com/f/13606/136061854/massi-valve-presta-tubeless-removable-core-2-units.jpg>
I noticed that the fine threads on the core, which I suspect are
stripped, are rolled and oddly shallow. The crest and the root are
rounded making slippage possible for a sloppy fit. Terminology
refresh:
<https://www.starrapid.com/wp-content/uploads/2021/08/Screw-thread-terminology.jpg>
I (visually) count 6 threads, where 6 times the thread pitch is about
equal to the core major diameter. That's about the minimum
recommended number of threads. I wouldn't have a problem if the core
threads were better formed. Notice that the core is inserted at a
slight angle in this photo:
<https://www.tradeinn.com/f/13606/136061854/massi-valve-presta-tubeless-removable-core-2-units.jpg>
I smell a loose fit, which is likely because there are no visible
"flat spots" for using a 4" crescent wrench to tighten the core. If
the core was intended to be installed "finger tight", without the
assistance of a wrench, then a loose fit is likely.

>How about corrosion aided by some basic rearragement in the customer's
>parts/bike storage environment? Some unmentioned, but galvanically
>furious exotic valve covers that a magically inclined, obsessive
>customer puts on, first thing, whenever he gets new tubes?

Methinks not. You might have missed my key point. There are too many
combinations of tube, stem, core and pump that will produce a flying
core. Corrosion damage is possible in one core and stem pair, but not
in the apparently numerous repetitions. A manufacturing defect is
more likely, where all the stems and cores have identical problem.
However, the tubes are from different vendors, so that's unlikely.

My point was for an identical failure to occur in a large number of
different combinations of tube, stem, core and pump, there has to be a
culprit or failure that is common to all the various combination. That
suggests the owner, with the assistance of the 4" crescent wrench, is
over-tightening the core, which thanks to the loose fit, is stripping
the threads.

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

On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>I'll confess that I've never seen removable Presta core. Here's a
>photo:
><https://www.lordgun.com/presta-removable-valve-core-2>

Here's a better photo of the Presta core.
<https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
Notice the rounded crest and root of the threads.

There is also a polished area on the opposing crests of the larger
threads which is the flat areas suitable for applying a torque
amplifying removal tool. Enlarging and inspecting the other photos
show the flat areas on all the previously mentioned photos. Sorry, I
missed it when I first looked at the photos.

It might be useful if the owner purchase a proper Presta core removal
tool:
<https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
Notice that none of the tools resemble a 4" crescent wrench.

"How to Remove a Presta Valve Core Without A Tool"
<https://www.youtube.com/watch?v=VvdJbrfdZLk>
Notice that a crescent wrench is not among the recommended tools.

The crescent wrench could be better utilized for rounding bolt heads
than for removing Presta cores.

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

On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
> On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <jeffl@cruzio.com>
> wrote:
>
>> I'll confess that I've never seen removable Presta core. Here's a
>> photo:
>> <https://www.lordgun.com/presta-removable-valve-core-2>
>
> Here's a better photo of the Presta core.
> <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
> Notice the rounded crest and root of the threads.
>
> There is also a polished area on the opposing crests of the larger
> threads which is the flat areas suitable for applying a torque
> amplifying removal tool. Enlarging and inspecting the other photos
> show the flat areas on all the previously mentioned photos. Sorry, I
> missed it when I first looked at the photos.
>
> It might be useful if the owner purchase a proper Presta core removal
> tool:
> <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
> Notice that none of the tools resemble a 4" crescent wrench.
>
> "How to Remove a Presta Valve Core Without A Tool"
> <https://www.youtube.com/watch?v=VvdJbrfdZLk>
> Notice that a crescent wrench is not among the recommended tools.
>
> The crescent wrench could be better utilized for rounding bolt heads
> than for removing Presta cores.
>

Thanks to you all, especially Mr Holtman and Mr Merriman for
confirming this is not an unique problem.

And to you for analysis. I have come to agree that
overtorque of a thin brass tube with resultant thread
deformation is the probable root of it.

I suggested he use traditional (non-removable-core) tubes
which are widely available.

p.s. I also use an American Crescent brand 4" adjustable
wrench but I also understand it's a thin brass tube and
torque accordingly.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Monday, January 23, 2023 at 6:36:19 AM UTC-8, AMuzi wrote:
> On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
> > On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <je...@cruzio.com>
> > wrote:
> >
> >> I'll confess that I've never seen removable Presta core. Here's a
> >> photo:
> >> <https://www.lordgun.com/presta-removable-valve-core-2>
> >
> > Here's a better photo of the Presta core.
> > <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
> > Notice the rounded crest and root of the threads.
> >
> > There is also a polished area on the opposing crests of the larger
> > threads which is the flat areas suitable for applying a torque
> > amplifying removal tool. Enlarging and inspecting the other photos
> > show the flat areas on all the previously mentioned photos. Sorry, I
> > missed it when I first looked at the photos.
> >
> > It might be useful if the owner purchase a proper Presta core removal
> > tool:
> > <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
> > Notice that none of the tools resemble a 4" crescent wrench.
> >
> > "How to Remove a Presta Valve Core Without A Tool"
> > <https://www.youtube.com/watch?v=VvdJbrfdZLk>
> > Notice that a crescent wrench is not among the recommended tools.
> >
> > The crescent wrench could be better utilized for rounding bolt heads
> > than for removing Presta cores.
> >
> Thanks to you all, especially Mr Holtman and Mr Merriman for
> confirming this is not an unique problem.
>
> And to you for analysis. I have come to agree that
> overtorque of a thin brass tube with resultant thread
> deformation is the probable root of it.
>
> I suggested he use traditional (non-removable-core) tubes
> which are widely available.
>
> p.s. I also use an American Crescent brand 4" adjustable
> wrench but I also understand it's a thin brass tube and
> torque accordingly.

I suppose that since I work so often on bicycles, that I know enough never to overtighten things like valve cores. I leave that to people like Liebermann who is willing to tell us all how to do these things when he doesn't ride bicycles.

On 1/23/2023 9:30 AM, Tom Kunich wrote:
> On Monday, January 23, 2023 at 6:36:19 AM UTC-8, AMuzi wrote:
>> On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
>>> On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <je...@cruzio.com>
>>> wrote:
>>>
>>>> I'll confess that I've never seen removable Presta core. Here's a
>>>> photo:
>>>> <https://www.lordgun.com/presta-removable-valve-core-2>
>>>
>>> Here's a better photo of the Presta core.
>>> <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
>>> Notice the rounded crest and root of the threads.
>>>
>>> There is also a polished area on the opposing crests of the larger
>>> threads which is the flat areas suitable for applying a torque
>>> amplifying removal tool. Enlarging and inspecting the other photos
>>> show the flat areas on all the previously mentioned photos. Sorry, I
>>> missed it when I first looked at the photos.
>>>
>>> It might be useful if the owner purchase a proper Presta core removal
>>> tool:
>>> <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
>>> Notice that none of the tools resemble a 4" crescent wrench.
>>>
>>> "How to Remove a Presta Valve Core Without A Tool"
>>> <https://www.youtube.com/watch?v=VvdJbrfdZLk>
>>> Notice that a crescent wrench is not among the recommended tools.
>>>
>>> The crescent wrench could be better utilized for rounding bolt heads
>>> than for removing Presta cores.
>>>
>> Thanks to you all, especially Mr Holtman and Mr Merriman for
>> confirming this is not an unique problem.
>>
>> And to you for analysis. I have come to agree that
>> overtorque of a thin brass tube with resultant thread
>> deformation is the probable root of it.
>>
>> I suggested he use traditional (non-removable-core) tubes
>> which are widely available.
>>
>> p.s. I also use an American Crescent brand 4" adjustable
>> wrench but I also understand it's a thin brass tube and
>> torque accordingly.
>
> I suppose that since I work so often on bicycles, that I know enough never to overtighten things like valve cores. I leave that to people like Liebermann who is willing to tell us all how to do these things when he doesn't ride bicycles.
>

Well a Presta threaded valve stem is 5.7mm OD, which leaves
4.96mm at thread root. On the inside it's threaded for a
4.6mm core or a wall thickness of about 0.2mm at thinnest
sections in brass. Most people would not observe a light
enough torque for that.

The repeated failures are caused IMHO by a deformed
(expanded) valve stem such that a new insert pops out like
the last insert.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On 1/23/2023 10:30 AM, Tom Kunich wrote:
>
>
> I suppose that since I work so often on bicycles, that I know enough never to overtighten things like valve cores. I leave that to people like Liebermann who is willing to tell us all how to do these things when he doesn't ride bicycles.

:-) Unlike you, Jeff hasn't repeatedly complained about his handlebars
slipping. Perhaps he's better at tightening things than you are!

--
- Frank Krygowski

On Mon, 23 Jan 2023 07:30:14 -0800 (PST), Tom Kunich
<cyclintom@gmail.com> wrote:

>On Monday, January 23, 2023 at 6:36:19 AM UTC-8, AMuzi wrote:
>> On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
>> > On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <je...@cruzio.com>
>> > wrote:
>> >
>> >> I'll confess that I've never seen removable Presta core. Here's a
>> >> photo:
>> >> <https://www.lordgun.com/presta-removable-valve-core-2>
>> >
>> > Here's a better photo of the Presta core.
>> > <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
>> > Notice the rounded crest and root of the threads.
>> >
>> > There is also a polished area on the opposing crests of the larger
>> > threads which is the flat areas suitable for applying a torque
>> > amplifying removal tool. Enlarging and inspecting the other photos
>> > show the flat areas on all the previously mentioned photos. Sorry, I
>> > missed it when I first looked at the photos.
>> >
>> > It might be useful if the owner purchase a proper Presta core removal
>> > tool:
>> > <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
>> > Notice that none of the tools resemble a 4" crescent wrench.
>> >
>> > "How to Remove a Presta Valve Core Without A Tool"
>> > <https://www.youtube.com/watch?v=VvdJbrfdZLk>
>> > Notice that a crescent wrench is not among the recommended tools.
>> >
>> > The crescent wrench could be better utilized for rounding bolt heads
>> > than for removing Presta cores.
>> >
>> Thanks to you all, especially Mr Holtman and Mr Merriman for
>> confirming this is not an unique problem.
>>
>> And to you for analysis. I have come to agree that
>> overtorque of a thin brass tube with resultant thread
>> deformation is the probable root of it.

Thanks.

For your amusement, I was looking at photos of 4 inch crescent
wrenches and found this item:
<https://countycomm.com/products/adjustable-wrench-titanium-4-inch-nsn-pending>
However, one of the photos shows something rather odd:
<https://cdn.shopify.com/s/files/1/1437/9632/products/IMG_4260.jpg>
That's a Motorola Quantar radio repeater. The coax connector is a TNC
connector which does not have flats or a hex nut for tightening. The
titanium crescent wrench seems perfect for rounding bolt heads and
damaging coax cable connectors.

>> I suggested he use traditional (non-removable-core) tubes
>> which are widely available.
>>
>> p.s. I also use an American Crescent brand 4" adjustable
>> wrench but I also understand it's a thin brass tube and
>> torque accordingly.

>I suppose that since I work so often on bicycles, that I know
>enough never to overtighten things like valve cores.

That's not the way it works. If you know how something works, you can
figure out what's broken and how to fix it. However, if you don't
know how something works, which appears to be your problem, the best
you can do is follow someone else's instructions.

>I leave that to people like Liebermann who is willing to tell
>us all how to do these things when he doesn't ride bicycles.

True. I like solving problems. You seem to enjoy creating problems.
That's why we get along so well.

In this case, I have never seen a Presta valve with a removable core.
Therefore, I have never worked with one. Yet, I was able to analyze
the problem, determine a likely point of failure, and suggest a
probable cause. If I had not known the limitations of rolled and
stamped threads, I would never have produced a solution. While first
hand experience is very useful, knowing how things work will suffice.

I mentioned this story previously in RBT, but it bears repeating. I
used to work for a manager who tended to lie if he didn't understand
the problem or know the answer. I didn't say anything because the
things he did know were very valuable for what we were doing. His
knowledge, based mostly on experience, was worth tolerating the lies.
The trick was to recognize the truths, which I gladly did because they
proved to be so valuable. In your case, I'm still waiting for some
valuable and useful truths.

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

On 1/23/2023 1:03 PM, Jeff Liebermann wrote:
> On Mon, 23 Jan 2023 07:30:14 -0800 (PST), Tom Kunich
> <cyclintom@gmail.com> wrote:
>
>> On Monday, January 23, 2023 at 6:36:19 AM UTC-8, AMuzi wrote:
>>> On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
>>>> On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <je...@cruzio.com>
>>>> wrote:
>>>>
>>>>> I'll confess that I've never seen removable Presta core. Here's a
>>>>> photo:
>>>>> <https://www.lordgun.com/presta-removable-valve-core-2>
>>>>
>>>> Here's a better photo of the Presta core.
>>>> <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
>>>> Notice the rounded crest and root of the threads.
>>>>
>>>> There is also a polished area on the opposing crests of the larger
>>>> threads which is the flat areas suitable for applying a torque
>>>> amplifying removal tool. Enlarging and inspecting the other photos
>>>> show the flat areas on all the previously mentioned photos. Sorry, I
>>>> missed it when I first looked at the photos.
>>>>
>>>> It might be useful if the owner purchase a proper Presta core removal
>>>> tool:
>>>> <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
>>>> Notice that none of the tools resemble a 4" crescent wrench.
>>>>
>>>> "How to Remove a Presta Valve Core Without A Tool"
>>>> <https://www.youtube.com/watch?v=VvdJbrfdZLk>
>>>> Notice that a crescent wrench is not among the recommended tools.
>>>>
>>>> The crescent wrench could be better utilized for rounding bolt heads
>>>> than for removing Presta cores.
>>>>
>>> Thanks to you all, especially Mr Holtman and Mr Merriman for
>>> confirming this is not an unique problem.
>>>
>>> And to you for analysis. I have come to agree that
>>> overtorque of a thin brass tube with resultant thread
>>> deformation is the probable root of it.
>
> Thanks.
>
> For your amusement, I was looking at photos of 4 inch crescent
> wrenches and found this item:
> <https://countycomm.com/products/adjustable-wrench-titanium-4-inch-nsn-pending>
> However, one of the photos shows something rather odd:
> <https://cdn.shopify.com/s/files/1/1437/9632/products/IMG_4260.jpg>
> That's a Motorola Quantar radio repeater. The coax connector is a TNC
> connector which does not have flats or a hex nut for tightening. The
> titanium crescent wrench seems perfect for rounding bolt heads and
> damaging coax cable connectors.
>
>>> I suggested he use traditional (non-removable-core) tubes
>>> which are widely available.
>>>
>>> p.s. I also use an American Crescent brand 4" adjustable
>>> wrench but I also understand it's a thin brass tube and
>>> torque accordingly.
>
>> I suppose that since I work so often on bicycles, that I know
>> enough never to overtighten things like valve cores.
>
> That's not the way it works. If you know how something works, you can
> figure out what's broken and how to fix it. However, if you don't
> know how something works, which appears to be your problem, the best
> you can do is follow someone else's instructions.
>
>> I leave that to people like Liebermann who is willing to tell
>> us all how to do these things when he doesn't ride bicycles.
>
> True. I like solving problems. You seem to enjoy creating problems.
> That's why we get along so well.
>
> In this case, I have never seen a Presta valve with a removable core.
> Therefore, I have never worked with one. Yet, I was able to analyze
> the problem, determine a likely point of failure, and suggest a
> probable cause. If I had not known the limitations of rolled and
> stamped threads, I would never have produced a solution. While first
> hand experience is very useful, knowing how things work will suffice.
>
> I mentioned this story previously in RBT, but it bears repeating. I
> used to work for a manager who tended to lie if he didn't understand
> the problem or know the answer. I didn't say anything because the
> things he did know were very valuable for what we were doing. His
> knowledge, based mostly on experience, was worth tolerating the lies.
> The trick was to recognize the truths, which I gladly did because they
> proved to be so valuable. In your case, I'm still waiting for some
> valuable and useful truths.
>
>

US made Crescent brand 4" adjustable is a popular little
thing with tight slides and crisp jaws:

https://www.2040-parts.com/crescent-adjustable-wrench-4-in-at14-vintage-crescent-tool-co-jamestown-ny-usa-i1030262/

It's not junk. User torque values are a real possibility for
a trouble source but not the tool itself.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On 1/23/2023 11:03 AM, Jeff Liebermann wrote:

<snip>

> For your amusement, I was looking at photos of 4 inch crescent
> wrenches and found this item:
> <https://countycomm.com/products/adjustable-wrench-titanium-4-inch-nsn-pending>

Only 0.52" jaw opening.

I use this one with about a 1" opening (actually about 1¹⁄₁₆"):
<https://www.aliexpress.us/item/2251832662508203.html>. It's quite well
made. I put one into each bike's tool bag since they're so inexpensive.

On Mon, 23 Jan 2023 14:14:26 -0600, AMuzi <am@yellowjersey.org> wrote:

>On 1/23/2023 1:03 PM, Jeff Liebermann wrote:
>> On Mon, 23 Jan 2023 07:30:14 -0800 (PST), Tom Kunich
>> <cyclintom@gmail.com> wrote:
>>
>>> On Monday, January 23, 2023 at 6:36:19 AM UTC-8, AMuzi wrote:
>>>> On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
>>>>> On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <je...@cruzio.com>
>>>>> wrote:
>>>>>
>>>>>> I'll confess that I've never seen removable Presta core. Here's a
>>>>>> photo:
>>>>>> <https://www.lordgun.com/presta-removable-valve-core-2>
>>>>>
>>>>> Here's a better photo of the Presta core.
>>>>> <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
>>>>> Notice the rounded crest and root of the threads.
>>>>>
>>>>> There is also a polished area on the opposing crests of the larger
>>>>> threads which is the flat areas suitable for applying a torque
>>>>> amplifying removal tool. Enlarging and inspecting the other photos
>>>>> show the flat areas on all the previously mentioned photos. Sorry, I
>>>>> missed it when I first looked at the photos.
>>>>>
>>>>> It might be useful if the owner purchase a proper Presta core removal
>>>>> tool:
>>>>> <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
>>>>> Notice that none of the tools resemble a 4" crescent wrench.
>>>>>
>>>>> "How to Remove a Presta Valve Core Without A Tool"
>>>>> <https://www.youtube.com/watch?v=VvdJbrfdZLk>
>>>>> Notice that a crescent wrench is not among the recommended tools.
>>>>>
>>>>> The crescent wrench could be better utilized for rounding bolt heads
>>>>> than for removing Presta cores.
>>>>>
>>>> Thanks to you all, especially Mr Holtman and Mr Merriman for
>>>> confirming this is not an unique problem.
>>>>
>>>> And to you for analysis. I have come to agree that
>>>> overtorque of a thin brass tube with resultant thread
>>>> deformation is the probable root of it.
>>
>> Thanks.
>>
>> For your amusement, I was looking at photos of 4 inch crescent
>> wrenches and found this item:
>> <https://countycomm.com/products/adjustable-wrench-titanium-4-inch-nsn-pending>
>> However, one of the photos shows something rather odd:
>> <https://cdn.shopify.com/s/files/1/1437/9632/products/IMG_4260.jpg>
>> That's a Motorola Quantar radio repeater. The coax connector is a TNC
>> connector which does not have flats or a hex nut for tightening. The
>> titanium crescent wrench seems perfect for rounding bolt heads and
>> damaging coax cable connectors.
>>
>>>> I suggested he use traditional (non-removable-core) tubes
>>>> which are widely available.
>>>>
>>>> p.s. I also use an American Crescent brand 4" adjustable
>>>> wrench but I also understand it's a thin brass tube and
>>>> torque accordingly.
>>
>>> I suppose that since I work so often on bicycles, that I know
>>> enough never to overtighten things like valve cores.
>>
>> That's not the way it works. If you know how something works, you can
>> figure out what's broken and how to fix it. However, if you don't
>> know how something works, which appears to be your problem, the best
>> you can do is follow someone else's instructions.
>>
>>> I leave that to people like Liebermann who is willing to tell
>>> us all how to do these things when he doesn't ride bicycles.
>>
>> True. I like solving problems. You seem to enjoy creating problems.
>> That's why we get along so well.
>>
>> In this case, I have never seen a Presta valve with a removable core.
>> Therefore, I have never worked with one. Yet, I was able to analyze
>> the problem, determine a likely point of failure, and suggest a
>> probable cause. If I had not known the limitations of rolled and
>> stamped threads, I would never have produced a solution. While first
>> hand experience is very useful, knowing how things work will suffice.
>>
>> I mentioned this story previously in RBT, but it bears repeating. I
>> used to work for a manager who tended to lie if he didn't understand
>> the problem or know the answer. I didn't say anything because the
>> things he did know were very valuable for what we were doing. His
>> knowledge, based mostly on experience, was worth tolerating the lies.
>> The trick was to recognize the truths, which I gladly did because they
>> proved to be so valuable. In your case, I'm still waiting for some
>> valuable and useful truths.

>US made Crescent brand 4" adjustable is a popular little
>thing with tight slides and crisp jaws:
>
>https://www.2040-parts.com/crescent-adjustable-wrench-4-in-at14-vintage-crescent-tool-co-jamestown-ny-usa-i1030262/
>
>It's not junk. User torque values are a real possibility for
>a trouble source but not the tool itself.

I didn't say the 4 inch crescent wrench was junk. I suggested that it
was not an appropriate tool for the intended purpose.

I used to carry a 2.5 inch crescent wrench in my pocket.
<https://www.google.com/search?q=2.5+inch+crescent+wrench&tbm=isch>
Very handy, but still not suitable for tightening Presta cores because
of the possibility of over-tightening.

When I'm faced with similar mysteries, I tend to ask myself "What
problem were they trying to solve?" In this case, my question is
"what caused the user to use a wrench instead of just finger
tightening the core?" My guess is that he had a problem with leaking
air from the inner tube(s) and assumed that it was a leaking valve.
(Assumption is the mother of all screwups).

He may then have followed the advice of this YouTube video:
"How To Fix A Leaky Tire Presta Valve Stem Valve Core Bike Blogger"
<https://www.youtube.com/watch?v=C7XzK0p_03o>

"How to fix a leaky tire with a presta valve? You may have a leaky
tire because the valve core on the inner tube valve stem shipped loose
from the factory."
I don't believe that the factory ships stems configured to fail when
initially used.

"To fix a leaky tire in this case all you need to do is make sure the
valve core body is tightened on the valve stem. Use some small pliers,
a wrench, or a valve core remover tool specifically for this purpose."
Notice that in the video, he was able to easily unscrew the core using
only his fingers and without the aid of additional tools. Using small
pliers or a wrench are likely to overtighten the core. Predictably,
the author of the video does not indicate whether his tightening of
the core solved his air leakage problem or whether his core was later
launched in the same manner as the original problem.

Since I don't have a Presta stem with a removable core handy, could
someone look at theirs and tell me if there is a rubber washer in the
base of the stem that would provide an air seal for the core? If so,
finger tight should be sufficient. Brute force with a wrench could
cut or distort a rubber washer, causing an (additional) air leak. If
this is the case, the owner tightening the core with a 4" crescent
wrench probably caused the valve leak (if the original leak was
elsewhere) or made it worse (if the original leak was in the stem).

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

On Mon, 23 Jan 2023 14:46:09 -0800, sms <scharf.steven@geemail.com>
wrote:

>On 1/23/2023 11:03 AM, Jeff Liebermann wrote:
>
><snip>
>
>> For your amusement, I was looking at photos of 4 inch crescent
>> wrenches and found this item:
>> <https://countycomm.com/products/adjustable-wrench-titanium-4-inch-nsn-pending>
>
>Only 0.52" jaw opening.
>
>I use this one with about a 1" opening (actually about 1¹???"):
><https://www.aliexpress.us/item/2251832662508203.html>. It's quite well
>made. I put one into each bike's tool bag since they're so inexpensive.

You may have missed my point. The photo of the wrench being used to
tighten the coaxial cable connector in the countycomm.com link above
would not work with any size crescent wrench (or adjustable spanner).
The problem is the TNC connector has a knurled round retaining shell.
A crescent wrench would just slide around the outside and not tighten
anything. For a crescent wrench to work properly, the retaining shell
would need to be hexagonal.

I prefer a thin jaw crescent wrench, which is a marginal substitute
for a cone wrench. Something like this:
<https://www.amazon.com/dp/B08L6TS8JX>
More:
<https://www.google.com/search?q=thin+jaw+crescent+wrench&tbm=isch>

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

On 1/24/2023 1:42 AM, Jeff Liebermann wrote:
> On Mon, 23 Jan 2023 14:14:26 -0600, AMuzi <am@yellowjersey.org> wrote:
>
>> On 1/23/2023 1:03 PM, Jeff Liebermann wrote:
>>> On Mon, 23 Jan 2023 07:30:14 -0800 (PST), Tom Kunich
>>> <cyclintom@gmail.com> wrote:
>>>
>>>> On Monday, January 23, 2023 at 6:36:19 AM UTC-8, AMuzi wrote:
>>>>> On 1/22/2023 1:14 PM, Jeff Liebermann wrote:
>>>>>> On Sun, 22 Jan 2023 10:57:22 -0800, Jeff Liebermann <je...@cruzio.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I'll confess that I've never seen removable Presta core. Here's a
>>>>>>> photo:
>>>>>>> <https://www.lordgun.com/presta-removable-valve-core-2>
>>>>>>
>>>>>> Here's a better photo of the Presta core.
>>>>>> <https://www.jensonusa.com/globalassets/product-images---all-assets/stans-no-tubes/tu404b00.jpg>
>>>>>> Notice the rounded crest and root of the threads.
>>>>>>
>>>>>> There is also a polished area on the opposing crests of the larger
>>>>>> threads which is the flat areas suitable for applying a torque
>>>>>> amplifying removal tool. Enlarging and inspecting the other photos
>>>>>> show the flat areas on all the previously mentioned photos. Sorry, I
>>>>>> missed it when I first looked at the photos.
>>>>>>
>>>>>> It might be useful if the owner purchase a proper Presta core removal
>>>>>> tool:
>>>>>> <https://www.google.com/search?q=presta+valve+core+removal+tool&tbm=isch>
>>>>>> Notice that none of the tools resemble a 4" crescent wrench.
>>>>>>
>>>>>> "How to Remove a Presta Valve Core Without A Tool"
>>>>>> <https://www.youtube.com/watch?v=VvdJbrfdZLk>
>>>>>> Notice that a crescent wrench is not among the recommended tools.
>>>>>>
>>>>>> The crescent wrench could be better utilized for rounding bolt heads
>>>>>> than for removing Presta cores.
>>>>>>
>>>>> Thanks to you all, especially Mr Holtman and Mr Merriman for
>>>>> confirming this is not an unique problem.
>>>>>
>>>>> And to you for analysis. I have come to agree that
>>>>> overtorque of a thin brass tube with resultant thread
>>>>> deformation is the probable root of it.
>>>
>>> Thanks.
>>>
>>> For your amusement, I was looking at photos of 4 inch crescent
>>> wrenches and found this item:
>>> <https://countycomm.com/products/adjustable-wrench-titanium-4-inch-nsn-pending>
>>> However, one of the photos shows something rather odd:
>>> <https://cdn.shopify.com/s/files/1/1437/9632/products/IMG_4260.jpg>
>>> That's a Motorola Quantar radio repeater. The coax connector is a TNC
>>> connector which does not have flats or a hex nut for tightening. The
>>> titanium crescent wrench seems perfect for rounding bolt heads and
>>> damaging coax cable connectors.
>>>
>>>>> I suggested he use traditional (non-removable-core) tubes
>>>>> which are widely available.
>>>>>
>>>>> p.s. I also use an American Crescent brand 4" adjustable
>>>>> wrench but I also understand it's a thin brass tube and
>>>>> torque accordingly.
>>>
>>>> I suppose that since I work so often on bicycles, that I know
>>>> enough never to overtighten things like valve cores.
>>>
>>> That's not the way it works. If you know how something works, you can
>>> figure out what's broken and how to fix it. However, if you don't
>>> know how something works, which appears to be your problem, the best
>>> you can do is follow someone else's instructions.
>>>
>>>> I leave that to people like Liebermann who is willing to tell
>>>> us all how to do these things when he doesn't ride bicycles.
>>>
>>> True. I like solving problems. You seem to enjoy creating problems.
>>> That's why we get along so well.
>>>
>>> In this case, I have never seen a Presta valve with a removable core.
>>> Therefore, I have never worked with one. Yet, I was able to analyze
>>> the problem, determine a likely point of failure, and suggest a
>>> probable cause. If I had not known the limitations of rolled and
>>> stamped threads, I would never have produced a solution. While first
>>> hand experience is very useful, knowing how things work will suffice.
>>>
>>> I mentioned this story previously in RBT, but it bears repeating. I
>>> used to work for a manager who tended to lie if he didn't understand
>>> the problem or know the answer. I didn't say anything because the
>>> things he did know were very valuable for what we were doing. His
>>> knowledge, based mostly on experience, was worth tolerating the lies.
>>> The trick was to recognize the truths, which I gladly did because they
>>> proved to be so valuable. In your case, I'm still waiting for some
>>> valuable and useful truths.
>
>> US made Crescent brand 4" adjustable is a popular little
>> thing with tight slides and crisp jaws:
>>
>> https://www.2040-parts.com/crescent-adjustable-wrench-4-in-at14-vintage-crescent-tool-co-jamestown-ny-usa-i1030262/
>>
>> It's not junk. User torque values are a real possibility for
>> a trouble source but not the tool itself.
>
> I didn't say the 4 inch crescent wrench was junk. I suggested that it
> was not an appropriate tool for the intended purpose.
>
> I used to carry a 2.5 inch crescent wrench in my pocket.
> <https://www.google.com/search?q=2.5+inch+crescent+wrench&tbm=isch>
> Very handy, but still not suitable for tightening Presta cores because
> of the possibility of over-tightening.
>
> When I'm faced with similar mysteries, I tend to ask myself "What
> problem were they trying to solve?" In this case, my question is
> "what caused the user to use a wrench instead of just finger
> tightening the core?" My guess is that he had a problem with leaking
> air from the inner tube(s) and assumed that it was a leaking valve.
> (Assumption is the mother of all screwups).
>
> He may then have followed the advice of this YouTube video:
> "How To Fix A Leaky Tire Presta Valve Stem Valve Core Bike Blogger"
> <https://www.youtube.com/watch?v=C7XzK0p_03o>
>
> "How to fix a leaky tire with a presta valve? You may have a leaky
> tire because the valve core on the inner tube valve stem shipped loose
> from the factory."
> I don't believe that the factory ships stems configured to fail when
> initially used.
>
> "To fix a leaky tire in this case all you need to do is make sure the
> valve core body is tightened on the valve stem. Use some small pliers,
> a wrench, or a valve core remover tool specifically for this purpose."
> Notice that in the video, he was able to easily unscrew the core using
> only his fingers and without the aid of additional tools. Using small
> pliers or a wrench are likely to overtighten the core. Predictably,
> the author of the video does not indicate whether his tightening of
> the core solved his air leakage problem or whether his core was later
> launched in the same manner as the original problem.
>
> Since I don't have a Presta stem with a removable core handy, could
> someone look at theirs and tell me if there is a rubber washer in the
> base of the stem that would provide an air seal for the core? If so,
> finger tight should be sufficient. Brute force with a wrench could
> cut or distort a rubber washer, causing an (additional) air leak. If
> this is the case, the owner tightening the core with a 4" crescent
> wrench probably caused the valve leak (if the original leak was
> elsewhere) or made it worse (if the original leak was in the stem).
>
>
>
>
http://www.yellowjersey.org/PV2PART.JPG

White seal is insert to valve body.
Black seal is valve itself

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971