Valve Stem Bending

In article <[email hidden]>, [email hidden] says...

Quoted message said:

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.

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

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David Kerber said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

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

Joel Trunick said:

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 hidden] Palo Alto CA

In article said:

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

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Tom Keats said:

In article said:

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

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

Quoted message said:

... 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)

Quoted message said:

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

[email hidden] says...

Quoted message said:

Quoted message said:

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

Quoted message said:

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

This is a multi-part message in MIME format.

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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 hidden]> wrote in message =
"]news:[email hidden]...

Quoted message said:

I was hoping someone could tell me why my valve stems end up "bending =

over"

Quoted message said:

and getting a hole. I've had two tubes go bad and apparently it was =

because

Quoted message said:

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

Quoted message said:

to bend, but I don't know for sure, or how to fix it. Is it simply a =

matter

Quoted message said:

of improper tire pressure? I noticed that the "sprocket protected" =

(that

Quoted message said:

band of rubber under the inner tube) is completely loose and that I =

can

Quoted message said:

remove the tire by hand w/o the use of a screwdriver. Are those bad =

signs?

Quoted message said:

=20
Any ideas on how to fix it so my next patch/inner tube doesn't meet =

the same

Quoted message said:

demise?
=20
Thank in advance,
=20
Joel Newbie bicycle repairer
=20 20 20

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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""][email hidden]"><FONT face=3DArial=20
size=3D2>[email hidden]</FONT></A><FONT face=3DArial = size=3D2>> wrote=20
in message </FONT><A=20 href=3D""]news:[email hidden]"><FONT
= face=3DArial=20 size=3D2>"]news:[email hidden]</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>

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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 hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

In article said:

If the tire is really the wrong size for your rim, get the right one,

else you

Quoted message said:

Quoted message said:

will continue to have the same problems. It's good to be detail

oriented and

Quoted message said:

Quoted message said:

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

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Joel Trunick said:

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

Quoted message said:

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.

Quoted message said:

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 hidden] Palo Alto CA

In article <[email hidden]>,

Joel said:

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.

Quoted message said:

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

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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

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

J

"Bernie" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Quoted message said:

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

Quoted message said:

deatils like that.