Valve Stem Bending

Discussion in 'Road Cycling' started by Joel, Jun 22, 2003.

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  1. Joel

    Joel Guest

    I was hoping someone could tell me why my valve stems end up "bending over" and getting a hole.
    I've had two tubes go bad and apparently it was because the valve stems end up getting bent over
    and crack.

    My theory is that the tire is slipping on the wheel causing the valve stem to bend, but I don't know
    for sure, or how to fix it. Is it simply a matter of improper tire pressure? I noticed that the
    "sprocket protected" (that band of rubber under the inner tube) is completely loose and that I can
    remove the tire by hand w/o the use of a screwdriver. Are those bad signs?

    Any ideas on how to fix it so my next patch/inner tube doesn't meet the same demise?

    Thank in advance,

    Joel Newbie bicycle repairer
     
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  2. David Kerber

    David Kerber Guest

    In article <[email protected]>, [email protected] says...
    > I was hoping someone could tell me why my valve stems end up "bending over" and getting a hole.
    > I've had two tubes go bad and apparently it was because the valve stems end up getting bent over
    > and crack.
    >
    > My theory is that the tire is slipping on the wheel causing the valve stem to bend, but I don't
    > know for sure, or how to fix it. Is it simply a matter of improper tire pressure? I noticed that
    > the "sprocket protected" (that band of rubber under the inner tube) is completely loose and that I
    > can remove the tire by hand w/o the use of a screwdriver. Are those bad signs?
    >
    > Any ideas on how to fix it so my next patch/inner tube doesn't meet the same demise?

    All you need to do is pump it up enough. I've never seen a valve stem move if the tire was properly
    inflated, and they can move a lot if it's under-inflated.

    --
    Dave Kerber Fight spam: remove the ns_ from the return address before replying!

    REAL programmers write self-modifying code.
     
  3. Bernie

    Bernie Guest

    David Kerber wrote:

    > In article <[email protected]>,
    > [email protected] says...
    > > I was hoping someone could tell me why my valve stems end up "bending over" and getting a hole.
    > > I've had two tubes go bad and apparently it was because the valve stems end up getting bent over
    > > and crack.
    > >
    > > My theory is that the tire is slipping on the wheel causing the valve stem to bend, but I don't
    > > know for sure, or how to fix it. Is it simply a matter of improper tire pressure? I noticed that
    > > the "sprocket protected" (that band of rubber under the inner tube) is completely loose and that
    > > I can remove the tire by hand w/o the use of a screwdriver. Are those bad signs?
    > >
    > > Any ideas on how to fix it so my next patch/inner tube doesn't meet the same demise?
    >
    > All you need to do is pump it up enough. I've never seen a valve stem move if the tire was
    > properly inflated, and they can move a lot if it's under-inflated.
    >
    > --
    > Dave Kerber Fight spam: remove the ns_ from the return address before replying!
    >
    > REAL programmers write self-modifying code.

    I've got to agree with Dave.
    (1) be sure the stem is straight when you inflate the newly installed tube.
    (2) inflate to the rated max for your tire. I find a regular stand type pump with a gauge is the
    best thing to use. You will never overinflate a tire this way or ruin a tube because the tire
    did not seat properly, because things happen at a slower more controlled pace.
    (3) if the stem has shifted and is now crooked, deflate the tube and do it all again. If you don't,
    the rim will wear into the rubber stem and kill your tube.
    (4) get some plastic tire tools (dirt cheap) and stop using sharp metal screwdrivers, so you don't
    accidentally ruin your tubes.

    If the tire is really the wrong size for your rim, get the right one, else you will continue to have
    the same problems. It's good to be detail oriented and particular about these things as you will
    ride or not ride depending... Best regards, and good luck! Bernie
     
  4. Jobst Brandt

    Jobst Brandt Guest

    Joel Trunick writes:

    > I was hoping someone could tell me why my valve stems end up "bending over" and getting a hole.
    > I've had two tubes go bad and apparently it was because the valve stems end up getting bent over
    > and crack.

    In which direction does the stem fail? Is it in line with the plane of the wheel or to one side? If
    it is to one side, it is most likely your pumping technique. When using a hand held (frame fit) pump
    whose pump head fits directly on the valve stem without a hose, the user must be careful to pump
    into the fist of the other hand, not by holding onto tire and rim.

    This is why Silca frame fit pumps no longer generally used. Most riders break off stems because they
    cannot master the art of pumping with these pumps. The most common solution is to use CO2 cartridges
    or a mini-pump that takes up to 200 strokes (no significant force) to fill the tire.

    Jobst Brandt [email protected] Palo Alto CA
     
  5. Tom Keats

    Tom Keats Guest

    In article <[email protected]>, Bernie <[email protected]> writes:

    > If the tire is really the wrong size for your rim, get the right one, else you will continue to
    > have the same problems. It's good to be detail oriented and particular about these things as you
    > will ride or not ride depending... Best regards, and good luck! Bernie

    And it helps to line up the pressure rating lettering on the tire with the valve stem. That way, if
    you forget what the rating is, it's easy to find it on the tire.

    cheers, Tom

    --
    -- Powered by FreeBSD Above address is just a spam midden. I'm really at: tkeats [curlicue] vcn
    [point] bc [point] ca
     
  6. Bernie

    Bernie Guest

    Tom Keats wrote:

    > In article <[email protected]>, Bernie <[email protected]> writes:
    >
    > > If the tire is really the wrong size for your rim, get the right one, else you will continue to
    > > have the same problems. It's good to be detail oriented and particular about these things as you
    > > will ride or not ride depending... Best regards, and good luck! Bernie
    >
    > And it helps to line up the pressure rating lettering on the tire with the valve stem. That way,
    > if you forget what the rating is, it's easy to find it on the tire.
    >
    > cheers, Tom
    >
    > --
    > -- Powered by FreeBSD Above address is just a spam midden. I'm really at: tkeats [curlicue] vcn
    > [point] bc [point] ca

    good point, good idea. I am always holding the tire up and rotating it, looking for deatils
    like that.
     
  7. Tom Sherman

    Tom Sherman Guest

    [email protected] wrote:
    > ... This is why Silca frame fit pumps no longer generally used. Most riders break off stems
    > because they cannot master the art of pumping with these pumps. The most common solution is to
    > use CO2 cartridges or a mini-pump that takes up to 200 strokes (no significant force) to fill
    > the tire.

    Another alternative is to use a portable pump with a hose. I have found the Topeak Morph pumps to
    work quite well.

    Tom Sherman - Quad Cities USA (Illinois side)
     
  8. On Mon, 23 Jun 2003 04:51:18 GMT, [email protected] wrote:

    >The most common solution is to use CO2 cartridges or a mini-pump that takes up to 200 strokes (no
    >significant force) to fill the tire.

    The image of someone pumping a mini pump, very quickly of course because of the no force issue,
    cannot help but be suggestive to me. Anyone else have that problem?

    Jasper
     
  9. Hunrobe

    Hunrobe Guest

    [email protected] says...

    >> I was hoping someone could tell me why my valve stems end up "bending over" and getting a hole.
    >> I've had two tubes go bad and apparently it was because the valve stems end up getting bent over
    >> and crack.
    >>
    >> My theory is that the tire is slipping on the wheel causing the valve stem to bend, but I don't
    >> know for sure, or how to fix it. Is it simply a matter of improper tire pressure? I noticed that
    >> the "sprocket protected" (that band of rubber under the inner tube) is completely loose and that
    >> I can remove the tire by hand w/o the use of a screwdriver. Are those bad signs?
    >>
    >> Any ideas on how to fix it so my next patch/inner tube doesn't meet the
    >same
    >> demise?

    1- Replace that "sprocket protector" with some real rim tape. Those rubber band style protectors are
    definitely less effective than rim tape. 2- Buy a set of tire levers. They're cheap and much easier
    on tubes and tires if you happen to slip. 3- Make sure you're using the right tube/tire combination
    for your wheel. 4- Inflate the tires to the proper pressure.

    Why is it "apparent" that the valve stem is bending? I'm guessing that the valve stem isn't bent or
    deformed but that your leaks are tiny tears in the tube where the stem attaches to the tube. If
    that's the case it's either a burr on the edge of the hole in the rim where the stem fits through,
    the wrong size/type tube (like a 25mm tube in a 20mm tire or a presta tube on a rim drilled for a
    schraeder tube) , improper installation, or a combination of these things.

    Regards, Bob Hunt
     
  10. Joel

    Joel Guest

    This is a multi-part message in MIME format.

    ------=_NextPart_000_01DE_01C339D5.501CFC40 Content-Type: text/plain; charset="iso-8859-1"
    Content-Transfer-Encoding: quoted-printable

    Wow, I can't believe the depth of diagnosis of what I thought would be = difficult to convey
    in a post!

    It just sounds like I'm not pumping it up enough, so Ill go with that. I = just using a compact tire
    pump (one that you can take with you), and its = probably not ideal and you all suggested some
    alternatives. The holes on = the valve stem is in line with the rim, and I noticed the stem getting
    = bent over, so I'm pretty convinced I got the correct answers. Ill also = look into getting that
    rim tape as mentioned.

    Any way to repair the valve stems? I realized that if I put a patch on = it, it will be too fat to
    fit thru the hole.

    Thanks! Joel

    "Joel" <[email protected]> wrote in message =
    news:[email protected]...
    > I was hoping someone could tell me why my valve stems end up "bending =
    over"
    > and getting a hole. I've had two tubes go bad and apparently it was =
    because
    > the valve stems end up getting bent over and crack.
    >=20
    > My theory is that the tire is slipping on the wheel causing the valve =
    stem
    > to bend, but I don't know for sure, or how to fix it. Is it simply a =
    matter
    > of improper tire pressure? I noticed that the "sprocket protected" =
    (that
    > band of rubber under the inner tube) is completely loose and that I =
    can
    > remove the tire by hand w/o the use of a screwdriver. Are those bad =
    signs?
    >=20
    > Any ideas on how to fix it so my next patch/inner tube doesn't meet =
    the same
    > demise?
    >=20
    > Thank in advance,
    >=20
    > Joel Newbie bicycle repairer
    >=20 20 20

    ------=_NextPart_000_01DE_01C339D5.501CFC40 Content-Type: text/html; charset="iso-8859-1"
    Content-Transfer-Encoding: quoted-printable

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META
    http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML
    6.00.2726.2500" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY>
    <DIV><FONT face=3DArial size=3D2>Wow, I can't believe the depth of = diagnosis of what=20 I
    thought would be difficult to convey in a post!</FONT></DIV>
    <DV><FONT face=3DArial size=3D2></FONT> </DIV>
    <DVI><FONT face=3DArial size=3D2>It just sounds like I'm not pumping it = up enough,=20 so Ill go
    with that. I just using a compact tire pump (one that you can = take=20 with you), and its
    probably not ideal and you all suggested some = alternatives.=20 The holes on the valve
    stem is in line with the rim, and I noticed = the stem=20 getting bent over, so I'm pretty
    convinced I got the correct answers. = Ill also=20 look into getting that rim tape as
    mentioned.</FONT></DIV>
    <DVII><FONT face=3DArial size=3D2></FONT> </DIV>
    <DVIII><FONT face=3DArial size=3D2><EM>Any way to repair the valve = stems?</EM> I=20 realized that
    if I put a patch on it, it will be too fat to fit thru the =

    hole.</FONT></DIV>
    <DIX><FONT face=3DArial size=3D2></FONT> </DIV>
    <DX><FONT face=3DArial size=3D2>Thanks!</FONT></DIV>
    <DXI><FONT face=3DArial size=3D2>Joel</FONT></DIV>
    <DXII><FONT face=3DArial size=3D2></FONT> </DIV>
    <DXIII><FONT face=3DArial size=3D2></FONT> </DIV>
    <DXIV><FONT face=3DArial size=3D2>"Joel" <</FONT><A=20
    href=3D"mailto:[email protected]"><FONT face=3DArial=20
    size=3D2>[email protected]</FONT></A><FONT face=3DArial = size=3D2>> wrote=20
    in message </FONT><A=20 href=3D"news:[email protected]"><FONT
    = face=3DArial=20 size=3D2>news:[email protected]</FONT></A>=
    <FONT=20 face=3DArial size=3D2>...</FONT></DIV><FONT face=3DArial size=3D2>> I = was
    hoping=20 someone could tell me why my valve stems end up "bending over"<BR>> = and=20
    getting a hole. I've had two tubes go bad and apparently it was = because<BR>>=20 the
    valve stems end up getting bent over and crack.<BR>> <BR>> My = theory=20 is that the
    tire is slipping on the wheel causing the valve stem<BR>> = to=20 bend, but I don't know
    for sure, or how to fix it. Is it simply a = matter<BR>>=20 of improper tire pressure? I
    noticed that the "sprocket protected" = (that<BR>>=20 band of rubber under the inner tube)
    is completely loose and that I = can<BR>>=20 remove the tire by hand w/o the use of a
    screwdriver. Are those bad=20 signs?<BR>> <BR>> Any ideas on how to fix it so my next =
    patch/inner tube=20 doesn't meet the same<BR>> demise?<BR>> <BR>> Thank in =
    advance,<BR>>=20 <BR>> Joel<BR>> Newbie bicycle repairer<BR>> <BR>>
    <BR>>=20 </FONT></BODY></HTML>

    ------=_NextPart_000_01DE_01C339D5.501CFC40--
     
  11. Joel

    Joel Guest

    I don't get the impression the tire is the wrong size for the rim, but the tire is old. Its probably
    the same age as the bicycle, about 12 years or so old. Obviously, the bike was only lightly used.
    The tire has a good amount of tread left, but could it have hardened enough along the rim that it
    slips instead of grabbing the rim tightly? It doesn't have a rubbery feel where the two meet.

    Joel

    "Tom Keats" <[email protected]> wrote in message news:[email protected]...
    > In article <[email protected]>, Bernie <[email protected]> writes:
    >
    > > If the tire is really the wrong size for your rim, get the right one,
    else you
    > > will continue to have the same problems. It's good to be detail
    oriented and
    > > particular about these things as you will ride or not ride depending... Best regards, and good
    > > luck! Bernie
    >
    > And it helps to line up the pressure rating lettering on the tire with the valve stem. That way,
    > if you forget what the rating is, it's easy to find it on the tire.
    >
    >
    > cheers, Tom
    >
    > --
    > -- Powered by FreeBSD Above address is just a spam midden. I'm really at: tkeats [curlicue] vcn
    > [point] bc [point] ca
     
  12. Jobst Brandt

    Jobst Brandt Guest

    Joel Trunick writes:

    > Wow, I can't believe the depth of diagnosis of what I thought would be difficult to convey
    > in a post!

    > It just sounds like I'm not pumping it up enough, so Ill go with that. I just using a compact tire
    > pump (one that you can take with you), and its probably not ideal and you all suggested some
    > alternatives. The holes on the valve stem is in line with the rim, and I noticed the stem getting
    > bent over, so I'm pretty convinced I got the correct answers. Ill also look into getting that rim
    > tape as mentioned.

    You still didn't describe the mode of stem bending you experience. Stems don't bend and crack from
    tire slippage. Therefore, I am curious about what shape the stem has when you take the tube from
    tire and rim. Is it bent to one side or in line with the tube? Where is the crack that leaks? If you
    explain this, the diagnosis would be much simpler and you wouldn't get such a flood of different
    answers because each respondent visualizes a different scenario.

    > Any way to repair the valve stems? I realized that if I put a patch on it, it will be too fat to
    > fit thru the hole.

    I can't visualize what you are patching nor can anyone else.

    ... and forget the "thanks in advance" a thoughtless comment implying that you cannot be bothered to
    reply to give thanks in the event you get some help.

    Jobst Brandt [email protected] Palo Alto CA
     
  13. Tom Keats

    Tom Keats Guest

    In article <%[email protected]>,
    "Joel" <[email protected]> writes:
    > I don't get the impression the tire is the wrong size for the rim, but the tire is old. Its
    > probably the same age as the bicycle, about 12 years or so old.

    Age doesn't have much effect on how well tires fit on rims. Some tires of a given size will easily
    slip onto rims, and others will take more effort. I guess there's some latitude in the
    manufacturing.

    > Obviously, the bike was only lightly used. The tire has a good amount of tread left, but could it
    > have hardened enough along the rim that it slips instead of grabbing the rim tightly? It doesn't
    > have a rubbery feel where the two meet.

    I doubt tire rubber "work hardens" (i.e: from slipping on the rim), otherwise such an effect would
    also be noticable on the treaded surface which experiences a lot more friction.

    I wonder if the difference in feel that you detect is attributable to extra texturing, or
    reinforcement around the tire's bead. Or maybe even the presence of the bead itself.

    Tire rubber /does/ become cracked and brittle with age -- some people refer to this as "dry rot",
    but it's really oxidation and gradual evaporation of volatile substances in the rubber. This
    actually causes the rubber to shrink, hence the cracking. Exposure to the elements accelerates the
    process, as it does with oxidation of anything. From what I've seen on discarded bikes, this effect
    is most apparent on the exposed parts of the tires.

    I'd just buy a new set of tires of the appropriate size -- "a new broom sweeps clean".

    Hand-held pressure gauges are cheap, and well worth the money, too.

    cheers, Tom

    --
    -- Powered by FreeBSD Above address is just a spam midden. I'm really at: tkeats [curlicue] vcn
    [point] bc [point] ca
     
  14. Joel

    Joel Guest

    There a hole on the side of the valve stem where air is leaking out of the tube. How do I fix this
    and still get the valve stem thru the rim?

    Joel
     
  15. Joel

    Joel Guest

    Yeah, great idea, so simple I wouldn't have thought of it. :)

    J

    "Bernie" <[email protected]> wrote in message news:[email protected]...
    >
    > >
    > > And it helps to line up the pressure rating lettering on the tire with the valve stem. That way,
    > > if you forget what the rating is, it's easy to find it on the tire.
    > >
    > > cheers, Tom
    > >
    > > --
    > > -- Powered by FreeBSD Above address is just a spam midden. I'm really at: tkeats [curlicue] vcn
    > > [point] bc [point] ca
    >
    > good point, good idea. I am always holding the tire up and rotating it,
    looking for
    > deatils like that.
     
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