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presta valve stems bending



 
 
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  #1  
Old November 19th 03, 11:01 PM
wle
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Default presta valve stems bending

what makes presta valve stems bend over?

almost all mine get bent somehow.

not sure if it is floor pump or the frame pump that does it.

or - well this can;t be it - the tire caps.

they get so bent that it is hard to screw them back closed because
the screwer thingy rubs the valve body.

i never use a schrader valve plus adapter, always a presta fitting.

?
wle.
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  #2  
Old November 19th 03, 11:25 PM
Pete Biggs
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Default presta valve stems bending

wle wrote:
what makes presta valve stems bend over?

almost all mine get bent somehow.

not sure if it is floor pump or the frame pump that does it.


It will be to do with one of those pumps (I don't know which particular
heads you've got). You're probably being too rough with the frame pump.

In future, try unscrewing the little presta nut by the minimum amount
that's needed to work and try and keep everything aligned well without
pushing/pulling sideways too much.

They are possible to bend back to some extent but don't bend more than
once whatever happens.

~PB


  #3  
Old November 20th 03, 07:10 PM
Zog The Undeniable
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Default presta valve stems bending

wle wrote:
what makes presta valve stems bend over?

almost all mine get bent somehow.


To remove a frame pump from a Presta valve, you should give the pump
barrel a sharp rap with your hand so it is knocked off the valve. Never
"wiggle" it off.

  #4  
Old November 23rd 03, 08:34 PM
wle
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Default presta valve stems bending

In future, try unscrewing the little presta nut by the minimum amount
that's needed to work and try and keep everything aligned well without
pushing/pulling sideways too much.


good idea.

wle.
  #5  
Old November 24th 03, 12:26 AM
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Default presta valve stems bending

anonymous writes:

What makes Presta valve stems bend over? Almost all mine get bent
somehow. Not sure if it is floor pump or the frame pump that does
it. or - well this can't be it - the tire caps.


Presta valve stems don't bend, they break off. You must be having
some other problem.

They get so bent that it is hard to screw them back closed because
the screwer thingy rubs the valve body.


You must mean the valve nut. That gets bent by using a bad pump chuck
and removing it by bending it from side-to-side. Pull the pump chuck
straight off. For a hose pump, this ought to be obvious, for a frame
fit pump with attached valve chuck this is done by pushing the pump
off with the palm of the hand.

How about observing when the valve nut becomes bent after each
inflation. That ought to be an easy method of finding the answer to
your first question.

Jobst Brandt

  #8  
Old November 24th 03, 05:19 AM
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Default presta valve stems bending

Pete Biggs writes:

What makes Presta valve stems bend over? Almost all mine get bent
somehow. Not sure if it is floor pump or the frame pump that does
it. or - well this can't be it - the tire caps.


Presta valve stems don't bend, they break off. You must be having
some other problem.


You must mean the valve nut. That gets bent by using a bad pump
chuck and removing it by bending it from side-to-side.


It seems strange to call the part on which the small knurled captive
nut turns a "nut". That is the part that gets bent.


How about "valve core stem" or just "valve core"?


That doesn't work either because Presta valves have removable cores,
similar to Schrader valves. These can be detected by two flat sides
on the valve cap thread, the means by which the core is removed.

How about threaded valve shaft and nut?

Jobst Brandt

  #10  
Old November 24th 03, 07:08 AM
John Dacey
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Default presta valve stems bending

On Mon, 24 Nov 2003, (The Face That
Lunched A Thousand Cranks) wrote:

Pete Biggs writes:
How about "valve core stem" or just "valve core"?


That doesn't work either because Presta valves have removable cores,
similar to Schrader valves. These can be detected by two flat sides
on the valve cap thread, the means by which the core is removed.

How about threaded valve shaft and nut?

Jobst Brandt


Stop talking Pidgin Bicyclese!!! The thing you call a valve shaft is a
_valve_ by definition. Adding unnecessary gilding to the word "valve"
can only be for the purpose of sounding self-important, just like
those folks you've previously branded as illiterati for trying to
foist "crankarm", "wheelset" and similar redundancies on an
unsuspecting rbr readership teetering on the cusp of analphabetism.
Check it out in the online Webster's Dictionary:

Main Entry: valve
fluff snipped, caps below added for emphasis
3 a : any of numerous mechanical devices by which the flow of liquid,
gas, or loose material in bulk may be started, stopped, or regulated
by a movable part that opens, shuts, or partially obstructs one or
more ports or passageways; also : THE MOVABLE PART OF SUCH A DEVICE

Welcome to the ranks of the Great Unwashed, Jobst. Benighted and
sometimes guilty of "driving the intelligence level of bike talk down
at an accelerated rate", we're nonetheless great fun at parties.

-------------------------------
John Dacey
Business Cycles, Miami, Florida
http://www.businesscycles.com
Now in our twenty-first year.
Our catalog of track equipment: eighth year online
-------------------------------
 




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