Cornstarch vs. Talc
da...@erinet.com
>So we've been told since our first ratty little 20" bikes that whenever we
>change our tubes, we've got to liberally douse said tubes in talcum
>powder. I've noted that this has in fact minimized the number of slow
>flats I've had recently. Okay, given, talc is a Good Thing(tm).
>
>But what if talc isn't available?
Talc is a soft, powdery stuff that occurs in nature. The white cliffs
at Dover, England are talc. The junk that's sold in stores as talcum
powder is and has been mostly corn starch.
>Today I had to change my tube at work, and couldn't find talc nto save my
>live. Found some corn starch in the kitchen (god knows where it came
>from) and user it instead. Seems the same consistency, and as the ancient
>addage goes, "If I could walk that way..."
Whenever I've had to change a tube away from home, I've noticed that
the powder is still in the tire from the original installation. Maybe
I'm using too much!
>So, will corn starch cause my rims to rot and fall of, or my tubes to
>become HardCord Christian Gumbies, or cars to mysteriously appear from
>nowhere and kill me? Or is it the fundamental in this case equivalent to
>talc?
Baby powder or corn starch should work just fine.
FWIW, I don't think the purpose of this powder is to minimize slow
leaks. I think you put it in the tire so that the tube can wiggle
around and get straight when you first inflate the tire. It is not
desireable to have the tube kinked or twisted, but sometimes this
happens when you insert a tube. The powder prevents this (or, at
least, minimizes this) from happening.
.........dave
Richard Strayer
>Talc is a powdered mineral, formerly used as a treatment for diaper
>rash. It is nasty stuff, and can get stuck in your lungs. Cornstarch
>has replaced it as a baby powder, though I don't know how well
>cornstarch would work in tires.
>
>Sheldon "No To Talc" Brown
Cornstarch is frequently used as a thickening agent in Chinese cuisine.
The only problem with using it in your bicycle tires is that an hour
after you ride, you feel like riding again.
RES
John Forrest Tomlinson
In <345D9CAB...@sheldonbrown.com> Sheldon Brown
<NoS...@sheldonbrown.com> writes:
>
>Talc is a powdered mineral, formerly used as a treatment for diaper
>rash. It is nasty stuff, and can get stuck in your lungs. Cornstarch
>has replaced it as a baby powder, though I don't know how well
>cornstarch would work in tires.
>
>weather.
>
>Talc is a poison, and I don't use it for any purpose.
>
>For more information on this stuff, see:
>
> http://www.parentsplace.com/cgi-bin/objects/web_doc/drweb241.html
>
> http://housecall.orbisnews.com/databases/ami/convert/002719.html
>
>Sheldon "No To Talc" Brown
Sheldon, I've been scrupulously applying talc to inner tubes for years,
believing that this helps the tube and tire slide against each other
rather than sticking. I'd supposed that this would make the tire
handle better. Do you think this is a useless practice?
JT
John Forrest Tomlinson
In <19971104011...@ladder01.news.aol.com> alanf...@aol.com
(AlanFetzer) writes:
>
>I have been using corn starch for the last ten years, sprinkling it
inside the
> tire and then making sure the entire inside surface is coated with
it.
> Result: no pinch flats or other problems, BUT my bike does seem to go
a little
> slower every year. I never thought about it before, but do you
suppose the
> corn starch is the real culprit?
>Alan F.
>
No, the bike is getting heavier.
JT
AlanFetzer
Jerry Brown
:
: Cornstarch is frequently used as a thickening agent in Chinese cuisine.
: The only problem with using it in your bicycle tires is that an hour
: after you ride, you feel like riding again.
:
: RES
:
:
So what if you are riding the aero type wheels that let water in? Guess you
would end up with sludge in your tires.
JB
da...@erinet.com
>Nathaniel Osborne writes:
>> So we've been told since our first ratty little 20" bikes that
>> whenever we change our tubes, we've got to liberally douse said
>> tubes in talcum powder. I've noted that this has in fact minimized
>> the number of slow flats I've had recently. Okay, given, talc is a
>> Good Thing(tm).
>Jobst Brandt replied
>This among other things is an urban legend that won't die. There is
>no benefit in putting talcum powder or a substitute in a tire casing.
>The practice is like bicycle tire treads that are miniature replicas
>of automobile treads... if it's good for cars, it must be good for a
>bicycle. Cars used talcum between tire and tube because tubes tended
>to vulcanize to the tire from the heat developed on hot roads.
>Pulling the tube out subsequently tore the tube and left parts stuck
>to the casing.
I doubt that "powder in tires" rates the title of "urban legend".
Bicycle tubes stick to tire casings -- not from heat, but from
getting wet. Powder won't prevent this after repeated wettings but it
will definitely slow down the process.
>Bicycles don't get hot enough and the tubes are relatively far
>stronger for the small contact area they have with the tire.
I've seen ultra-light tubes stick so that they tear on removal --
usually at a seam. Invaribly, this happens 10 miles from nowhere when
you forgot to bring along a spare tube. The problem is compounded
because you are making a hurried repair on the roadside.
> Talcum
>has no effect on punctures of any kind other than to let the air out
>faster when one does occur. A tube stuck to the casing will allow one
>to ride a considerable distance because the thorn that penetrates
>plugs the casing hole and the tube hole has no outlet. I have found
>thorns the next morning when I prepared to ride to work, because
>coming home the tire had not yet lost enough air. The tube will stick
>to the casing of a non powdered casing.
>The only difference it that it is water soluble, but then who cares.
>Talcum cakes up in the wet although it doesn't dissolve.
There is little difference between the products, Sheldon's comments
notwithstanding. I didn't originate this thread but I still plan on
using powder in tire casings.
> Has anyone explained what talcum powder does?
The only uses I can think are these. It makes installing the tube
easier -- minimizes the risk that the tube will remain twisted or
kinked when first inflated. Careful installation will prevent this.
But you cannot see inside the tire to know the tube is twisted.
The other purpose is to ease removal of the tube at a later time.
Powder won't last forever -- repeated wettings will defeat any use.
However, I have seen it still working (still in powder form) after
several years.
FWIW, some tubes come out of the box lightly coated with powder. There
is no consistency on this -- some manufacturers use it, some don't. I
have never seen a comment or explanation on the box regarding this
practice.
I also note that _Bicycling Magazine's Complete Guide to Bicycle
Maintenance and Repair_ mentions the practice:
"4. Talc. This much overlooked substance is a _necessity_
for smooth tire manipulation. A tube without talc tends to
stick to its tire and is much harder to force into position..
Sprinkle some into the palm of your hand and draw the
partially inflated tube through it. Then dust the inside of
the tire by putting some talc into the bottom and rotating
the casing while spreading the talc with a soft brush. With
many tires, the use of talc spells the difference between
_success and failure_." [emphasis added]
Fear mongering comes from all sides in this debate!
In my opinion, powder won't prevent flats, minimize leaks or anything
of the sort. It is not a necessity and will probably not spell the
difference between "success and failure". You can definitely live
without it.
The only disadvantage is one Jobst suggested -- that lack of powder
might actually discourage the leak if there was an external puncture.
But, this would require a very tight seal between the tube and casing.
..................dave
Jobst Brandt
Alan Fetzer writes:
Please explain how powder between tire and tube prevents pinch flats.
Jobst Brandt <jbr...@hpl.hp.com>
Al Raden
Everyone in this interesting thread is missing the most important reason for
using talc on tubes - I use baby powder on tubes before folding them and storing
them in a zip lock... this makes them smell so much better than untreated
rubber.
Bob Hicks wrote:
> I have 2 takes on the powder problem:
>
> 1) powder on the tube reduces the chance that I will screw up and pinch the
> tube on installation. ....
--
- Al __o
_`\<,
...(*)/(*)
Bob Hicks
In my comment about setting up a spare with the tube already inside the
tire, I neglected to mention that it is necessary to mount the tire first
and ride it for a while (couple of outings perhaps) so that the tube is
properly stuck inside the tire.
Tracy A. Ferrell
I use talc because it makes it easier to get
the tire back on. I never use a tool to get
the tire on (for fear of nicking the tube)
and find, especially with new tires, that
it's almost impossible without the talc.
How do others deal with installing 700X25
or smaller tires?
Tracy tracy....@rss.rockwell.com
............in Sunny San Diego, CA, USA
capt...@sheldonbrown.com
John Forrest Tomlinson wrote:
>
> Sheldon, I've been scrupulously applying talc to inner tubes for years,
> believing that this helps the tube and tire slide against each other
> rather than sticking. I'd supposed that this would make the tire
> handle better. Do you think this is a useless practice?
Probably useless; certainly not necessary.
I never use the stuff...I've put some nasty stuff in my lungs on
occasion, but I don't "do" talc.
For the average cyclist, dealing with an average number of flats, this is
probably not a real issue. For a working mechanic, it is cause for
concern.
Happy Guy Fawkes Day to one and all...
Sheldon "Saying No To White Powder" Brown
Newtonville, Massachusetts
+-------------------------------------------+
| I millihelen = the amount of |
| beauty required to launch one ship. |
| --Peter Shickele |
+-------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-1040 FAX 617-244-1041
http://www.sheldonbrown.com/harris
-------------------==== Posted via Deja News ====-----------------------
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Stella Hackell
In article <63q2l4$ee4$1...@newsgate.sps.mot.com>, Lo...@the.sig (Lo...@the.sig)
wrote:
> > Talcum powder has most certainly been implicated in cancer
> > of the female reproductive organs (I think ovarian cancer).
> "Most certainly"? Where, in your imagination?
In the medical literature, Smarty Pants. Here are some references and
abstracts.
(1)
http://oncolink.upenn.edu/pdq_html/cites/09/09696.html
Harlow BL, Cramer DW, Bell DA, et al.: Perineal
exposure to talc and
ovarian cancer risk. Obstetrics and Gynecology
80(1): 19-26, 1992.
OBJECTIVE: We sought to determine whether the use of
talc in genital hygiene increases the risk for epithelial ovarian cancer.
METHODS: We interviewed 235 white women diagnosed with epithelial
ovarian cancer between 1984-1987 at ten Boston metropolitan area hospitals
and 239 population-based controls of similar race, age, and residence.
RESULTS: Overall,49% of cases and 39% of controls reported exposure to talc,
via direct application to the perineum or to undergarments, sanitary napkins,
or diaphragms, which yielded a 1.5 odds ratio (OR) for ovarian cancer (95%
confidence interval [CI] 1.0-2.1). Among women with perineal exposure to
talc, the risk was significantly elevated in the subgroups of women who
applied it: 1) directly as a body powder (OR 1.7, 95% CI 1.1-2.7), 2) on a
daily
basis (OR 1.8, 95% CI 1.1-3.0), and 3) for more than 10 years
(OR 1.6, 95% CI 1.0-2.7). The greatest ovarian cancer risk associated with
perineal talc use was observed in the subgroup ofwomen estimated to have
made more than 10,000 applications during years when they were ovulating
and had an intact genital tract (OR 2.8, 95% CI 1.4-5.4); however, this degree
of exposure was found in only 14% of the women with ovarian cancer.
CONCLUSIONS:
These data support the concept that a life-time pattern of perineal talc use
may increase the risk for epithelial ovarian cancer but is unlikely to be the
etiology for the majority of epithelial ovarian cancers. (24 Refs)
(2)
Cancer 79:2396-401, 1997
Copyright © 1997 American Cancer Society. All rights reserved.
Published by John Wiley & Sons, Inc.
Perineal Talc Exposure and Risk of Ovarian
Carcinoma
Stella Chang, B.A., Harvey A. Risch, M.D., Ph.D.
Department of Epidemiology and Public Health, Yale University School
of Medicine, New Haven, Connecticut.
Received October 23, 1996; revision received January 31, 1996;
accepted January 31, 1996.
ABSTRACT
BACKGROUND. Clinical and epidemiologic studies have indicated the
possible existence of an association between ovarian carcinoma and
talcum powder use. Talc particles have been detected in histologic sections
of ovarian carcinomas. It has also been demonstrated that inert
particles travel from the perineum to the ovaries. Results from
epidemiologic investigations have varied, from risks increased by twofold
to no significant risk detected.
METHODS. A total of 450 patients with borderline and invasive ovarian
carcinoma and 564 population controls in metropolitan Toronto and
nearby areas of southern Ontario, Canada, were identified. These subjects
were interviewed about their reproductive and menstrual histories as well
as
their exposure to dusting powders. Continuous unconditional logistic
regression methods were used for analysis.
RESULTS. Exposure to talc, via sanitary napkins, direct application to the
perineum, or both, was significantly associated with risk of ovarian carcinoma
(odds ratio [OR] 1.42, 95% confidence interval [CI] 1.08-1.86). A
borderline-significant association was detected between
duration of talc exposure and risk (OR 1.09, 95% CI 0.98-1.21,
per 10 years of exposure). No significant association was found between
frequency of exposure and risk. In comparing
invasive and borderline carcinomas, risk remained elevated for both
carcinoma types. Only risk for invasive carcinoma was statistically
significant.
CONCLUSIONS. This investigation supports previous contentions that
exposure to talc may increase risk of ovarian carcinoma. Questionable trends in
duration and frequency of exposure suggest that further studies may be
needed to
clarify the role of talc in the etiology of this disease.
The American Journal of Epidemiology also published an article
recently with similar conclusions, but I haven't found it yet.
So talc, while not the primary cause of ovarian cancer, is indeed a
risk factor, and a completely avoidable one.
> Mark
> R13...@email.sps.mot.com
--
Stella Hackell ste...@apple.com
There is a principle which is a bar against all information, which is
proof against all arguments and which can not fail to keep a man in
everlasting ignorance--that principle is contempt prior to
investigation. ---Herbert Spencer
Lo...@the.sig
In article <stella-ya0231800...@news.apple.com>
ste...@apple.com (Stella Hackell) writes:
> > "Most certainly"? Where, in your imagination?
>
> In the medical literature, Smarty Pants. Here are some references and
> abstracts.
>
Stella,
Apologies for the for the sarcastic comment...thanks for the
enlightenment.
> There is a principle which is a bar against all information, which is
> proof against all arguments and which can not fail to keep a man in
> everlasting ignorance--that principle is contempt prior to
> investigation. ---Herbert Spencer
"In God we trust; everyone else brings data."
---Me
Ole Blokhus
I've found that talcum is essential when installing Panaracer Greenlite tubes
on my MTB. The tubes are not very elastic, and upon inflation in a 2.0"
tire they permanently strech. If I don't use talcum, the tube will stick to
the inside of the tire, and it will only expand down into the rim. This again
makes the tube so thin in that area that it will puncture after a while. Mavic
217s are really bad in this instance, because they are deeper than most MTB-
rims.
Ole.
--
Ole Blokhus
ol...@powertech.no
Charles Maurer
In article <stella-ya0231800...@news.apple.com>,
ste...@apple.com (Stella Hackell) wrote:
> In article <63q2l4$ee4$1...@newsgate.sps.mot.com>, Lo...@the.sig (Lo...@the.sig)
> wrote:
>
> > > Talcum powder has most certainly been implicated in cancer
> > > of the female reproductive organs (I think ovarian cancer).
>
>
> > "Most certainly"? Where, in your imagination?
>
> In the medical literature, Smarty Pants. Here are some references and
> abstracts.
>
>
I know nothing about this subject but the abstracts you supply are highly
questionable. It is impossible to calculate risk from a retrospective
study. The full study may show some statistical legerdemain that is not
reflected by the abstract but I doubt it.
--
Charles Maurer
5 Grandview Court
Dundas, ON L9H 5C8
Canada
telephone & fax: 905.627.7035
John Forrest Tomlinson
In <MaurerC-0511...@empc-port27.net.mcmaster.ca>
Mau...@Claret.Psychology.McMaster.CA.cut.off.after.ca (Charles Maurer)
writes:
>In article <stella-ya0231800...@news.apple.com>,
>ste...@apple.com (Stella Hackell) wrote:
>
>> In article <63q2l4$ee4$1...@newsgate.sps.mot.com>, Lo...@the.sig
(Lo...@the.sig)
>> wrote:
>>
>> > > Talcum powder has most certainly been implicated in cancer
>> > > of the female reproductive organs (I think ovarian cancer).
>>
>>
>> > "Most certainly"? Where, in your imagination?
>>
>> In the medical literature, Smarty Pants. Here are some references
and
>> abstracts.
>>
>>
>
>I know nothing about this subject but the abstracts you supply are
highly
>questionable. It is impossible to calculate risk from a retrospective
>study. The full study may show some statistical legerdemain that is
not
>reflected by the abstract but I doubt it.
>
>--
Stella said "implicated", not "proven." Would you be happy if your
wife or daughter were using talc on their chamois?
JT
Paul Smee
In article <MaurerC-0511...@empc-port27.net.mcmaster.ca>,
Charles Maurer <Mau...@Claret.Psychology.McMaster.CA.cut.off.after.ca> wrote:
>I know nothing about this subject but the abstracts you supply are highly
>questionable. It is impossible to calculate risk from a retrospective
>study. The full study may show some statistical legerdemain that is not
>reflected by the abstract but I doubt it.
No offense intended, but I'm more inclined to credit a study in a
properly peer-reviewed journal, than a debunking of the study's
methodology produced by someone who claims to 'know nothing about the
subject' and who has only seen the abstract. I too know nothing about
the subject, so I'm simply working from first principles here. YMMV.
BikeTires
I understand that "JB" has posted the "facts"? regarding the use of talc, I am
not aware of the tests done to give JB his fact response.
But here are some opinions, for lack of a better way of putting it, talc acts
somewhat like a lubricant, indeed it does assist you in the mounting of the
tires to rims, it makes it much easier to stop from pinching tubes at
mounting as well as in use, You can't say that it is impossible to stop pinch
flats' how would you know, "maybe" it stopped one that's better than none.
I think the important issue is it can't hurt, if you "think" it helps then use
it. It's a real waste of time "IMO" to "FACT" this one to death, Just Do
it the way you want to.
PS I always use it to ease mounting.
Regards,
Mike Sullivan
Vittoria North America
Charles Maurer
In article <63sebr$1...@dfw-ixnews7.ix.netcom.com>,
jt...@ix.netcom.com(John Forrest Tomlinson) wrote:
> >>
> >
> >I know nothing about this subject but the abstracts you supply are
> highly
> >questionable. It is impossible to calculate risk from a retrospective
> >study. The full study may show some statistical legerdemain that is
> not
> >reflected by the abstract but I doubt it.
> >
> >--
>
>
> Stella said "implicated", not "proven." Would you be happy if your
> wife or daughter were using talc on their chamois?
>
As I said, I know nothing about this subject. I would be neither happy
nor unhappy for her to use talc. Nor would I be likely to pay attention
to implications from research of this sort.
Charles Maurer
In article <63st35$m...@hplms2.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
Brandt) wrote:
> Charles Maurer writes:
>
> > Is a fold likely to cause increase the probability of flats?
>
> In the long run yes but that is because rubber that is stressed
> oxidizes more rapidly. A stretched rubber band will crack and fail
> faster than a relaxed one if both are stretch tested after exposure
> for a longer time. The tube will develop cracks on the stretched part
> of the fold more readily than elsewhere, but not much.
Might it make sense, then, to smear wax on the folded part of the tube?
Jobst Brandt
Mike Sullivan writes:
> I understand that "JB" has posted the "facts"? regarding the use of
> talc, I am not aware of the tests done to give JB his fact response.
> But here are some opinions, for lack of a better way of putting it,
> talc acts somewhat like a lubricant, indeed it does assist you in
> the mounting of the tires to rims, it makes it much easier to stop
> from pinching tubes at mounting as well as in use, You can't say
> that it is impossible to stop pinch flats' how would you know,
> "maybe" it stopped one that's better than none.
I'm glad you can counter the evidence I presented with "some opinions".
That's hard for me to disprove. Maybe's are often tough to disprove.
> I think the important issue is it can't hurt, if you "think" it
> helps then use it. It's a real waste of time "IMO" to "FACT" this
> one to death, Just Do it the way you want to.
The problem is that the proponents of its use try to make a case that all
riders should use it. It is that aspect that brings my disagreement. As
I said, throwing salt over one's shoulder was held in similar reverence
for a long time with the same arguments that you bring.
Jobst Brandt <jbr...@hpl.hp.com>
TBGibb
In article <345F52...@brooktree.com>, "Tracy A. Ferrell"
<tr...@brooktree.com> writes:
>I use talc because it makes it easier to get
>the tire back on. I never use a tool to get
>the tire on (for fear of nicking the tube)
>and find, especially with new tires, that
>it's almost impossible without the talc.
>
>How do others deal with installing 700X25
>or smaller tires?
Patience and sore thumbs.
Tom Gibb <TBG...@aol.com>
Noclueatal
charles maurer writes
> >I know nothing about this subject but the abstracts you supply are
> highly
> >questionable. It is impossible to calculate risk from a retrospective
> >study. The full study may show some statistical legerdemain
and:
>As I said, I know nothing about this subject. I would be neither happy
>nor unhappy for her to use talc. Nor would I be likely to pay attention
>to implications from research of this sort.
if you know nothing about the subject, and don't care about it either, why do
you keep posting about it?
noclueatal
Stella Hackell
Charles Maurer wrote earlier:
> > >I know nothing about this subject but the abstracts you supply are
> > highly
> > >questionable. It is impossible to calculate risk from a retrospective
> > >study. The full study may show some statistical legerdemain that is
> > not
> > >reflected by the abstract but I doubt it.
I'm not sure I understand.
When you say "It is impossible to calculate risk from a
retrospective study," do you mean it is impossible to determine whether
there is any degree of risk, or that it is impossible to quantify the risk?
And what kind of study would one use to calculate risk?
I'm uneducated in statistics, so I'm not qualified to judge the study.
I do expect peer-reviewed journals to be fairly reliable sources of
information, though they can be flawed, of course.
--
Stella Hackell ste...@apple.com
An open mind has but one disadvantage: it collects dirt.
Kenneth Sole
Mau...@Claret.Psychology.McMaster.CA.cut.off.after.ca (Charles
Maurer) wrote:
»In article <63st35$m...@hplms2.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
»Brandt) wrote:
»
»> Charles Maurer writes:
»>
»> > Is a fold likely to cause increase the probability of flats?
»>
»> In the long run yes but that is because rubber that is stressed
»> oxidizes more rapidly. A stretched rubber band will crack and fail
»> faster than a relaxed one if both are stretch tested after exposure
»> for a longer time. The tube will develop cracks on the stretched part
»> of the fold more readily than elsewhere, but not much.
»
»
»Might it make sense, then, to smear wax on the folded part of the tube?
No chemist I, but certain "waxes" will (almost immediately) eat
into certain "rubber-like" materials. Years ago I knew someone
who ruined an otherwise perfect double kayak skin because he
thought that the frame would slide in more easily if he applied
"just a touch of wax" as a lubricant...
--
-Kenneth
Please respond here, and also via email (after removing "SPAMLESS.")
Jobst Brandt
Charles Maurer writes:
>>> Is a fold likely to cause increase the probability of flats?
>> In the long run yes but that is because rubber that is stressed
>> oxidizes more rapidly. A stretched rubber band will crack and fail
>> faster than a relaxed one if both are stretch tested after exposure
>> for a longer time. The tube will develop cracks on the stretched
>> part of the fold more readily than elsewhere, but not much.
> Might it make sense, then, to smear wax on the folded part of the tube?
I doubt it, because most waxes are petroleum products and would
adversely affect the rubber of the tube. Since the tube leaks by
diffusion, air can get to these parts, although in a reduced rate.
Cracks take a long time to develop. I have found folds in tubes that
were pulled from a tire that was worn through. It showed no signs of
developing a leak.
Jobst Brandt <jbr...@hpl.hp.com>
Robert Chung
In article <stella-ya0231800...@news.apple.com>,
Stella Hackell <ste...@apple.com> wrote:
>Charles Maurer wrote earlier:
>
>> > >I know nothing about this subject but the abstracts you supply are
>> > highly
>> > >questionable. It is impossible to calculate risk from a retrospective
>> > >study. The full study may show some statistical legerdemain that is
>> > not
>> > >reflected by the abstract but I doubt it.
>
>
>I'm not sure I understand.
>When you say "It is impossible to calculate risk from a
>retrospective study," do you mean it is impossible to determine whether
>there is any degree of risk, or that it is impossible to quantify the risk?
>And what kind of study would one use to calculate risk?
I think Charles misunderstands the statistical technique being used.
It is true that in isolation, a retrospective study cannot by *itself*
establish overall risk of a disease (in part because of selectivity
bias in who survives to be studied, in part because you can't figure out
who would've gotten the disease anyway). But the studies that Stella
cited weren't of that poor design. The studies she cited used control
populations against which to compare, and the results are presented
in terms of "odds ratios" or "relative risks" rather than raw risk.
The results are reported in comparison to the control population, which
is why you see results that look like, "an OR (odds ratio) of 1.5." This
means that compared to the control population, the study population
had an odds of experiencing the event under study 1.5 times as great.
Now, it is certainly true that not all medical research studies are
valid, but in my experience it is far more common for the study to be
flawed by the choice of controls rather than for the statistical method
to be inadequately applied. Charles' blanket statement that "it's
impossible to calculate risk from a retrospective study" is literally
true but functionally misleading since that was not done here.
Having said that, from an epidemiological point of view, the exposure
cited was prolonged. I wouldn't use talc in my shorts if I were a woman,
but I wouldn't worry about past exposure if it had occurred infrequently.
--Robert Chung, PhD (ch...@demog.berkeley.edu)
Medical Care Epidemiologist
Matt O'Toole
Jobst Brandt wrote in message <6400pg$6...@hplms2.hpl.hp.com>...
>From this I take it you don't use tire levers to mount your tires.
>Who started this macho concept of "real bikers don't use tire irons".
>I've watched people work their fingers red trying to put on a tire
>with tire irons lying right there. You can pinch a tube just as well
>by hand, it only takes longer and hurts while your at it.
I don't use tire irons if I can avoid it. More specifically, I don't use
tires that require tire irons. This is the number one criteria in choosing
tires for me. Otherwise, there are good tires from all manufacturers these
days, so I choose the ones that are easiest to remove and replace.
Michelin mountain bike tires, and all Continentals are just too hard to get
off and on. There is no reason for this that I can see, and I consider it a
flaw in the design.
Matt O.
Tom Scarvie
John Forrest Tomlinson wrote:
> Sheldon, I've been scrupulously applying talc to inner tubes for years,
> believing that this helps the tube and tire slide against each other
> rather than sticking. I'd supposed that this would make the tire
> handle better. Do you think this is a useless practice?
Not that I talc, myself (though I have been known to talc myself...),
but the above reasoning is similar to the only idea I've ever heard that
MIGHT make me POSSIBLY consider dusting my tubes. A talc-believing
acquaintance of mine has earnestly explained to me that it reduces
adhesion between tube and casing and therefore makes the tire more
supple (as per John T., above) and gives (drumroll, maybe?) less rolling
resistance.
Surely if we can inch even a minute amount closer to this Holy Grail of
cycling technology, the ZERO ROLLING RESISTANCE WHEEL, we should jump at
the chance and fill our bike shops with monstrous clouds of billowing
talc. This will compliment my prototype mag-lev wheel bearings
perfectly...
Whose got the numbers? Jobst, you put some talc'ed rubber on that tire
tester of yours yet? I mean, my wheels do go round and round and round
and round and...all that extra friction just has to add up in the end.
Talcum Tom
Charles Maurer
In article <stella-ya0231800...@news.apple.com>,
ste...@apple.com (Stella Hackell) wrote:
> Charles Maurer wrote earlier:
>
> > > >I know nothing about this subject but the abstracts you supply are
> > > highly
> > > >questionable. It is impossible to calculate risk from a retrospective
> > > >study. The full study may show some statistical legerdemain that is
> > > not
> > > >reflected by the abstract but I doubt it.
>
>
> I'm not sure I understand.
> When you say "It is impossible to calculate risk from a
> retrospective study," do you mean it is impossible to determine whether
> there is any degree of risk, or that it is impossible to quantify the risk?
> And what kind of study would one use to calculate risk?
>
> I'm uneducated in statistics, so I'm not qualified to judge the study.
> I do expect peer-reviewed journals to be fairly reliable sources of
> information, though they can be flawed, of course.
>
> --
To know the risk of a malady to a population, you need to know (a) the
number of people who have the malady and (b) the number of people in the
population. The risk is the first divided by the second. A retrospective
study finds people with the malady and nothing more. It does not tell you
the size of the population.
It may be possible to learn the size of the population by other means, of
course. Through census data, for instance. But it would be an
interesting census that asked women whether they use talcum powder on
their genitals. Since half of the calculation of risk depends on a
reliable determination of the population, and since this determination is
anything but straightforward, a study whose abstract ignores this does
not sound promising.
If that population is known, you must also know what proportion of that
population you might be expected to sample in the hospital/s where you
found your patients. This is also problematic.
Finally, to examine the risk of talc, one must hold all other factors
constant. This requires comparing talc-users who developed cancer with
non-talc users who are similar in age, marital status, socio-economic
status, number of sexual partners, sexual activity, etc. Furthermore,
women may decide to use talc because they because of physiological or
morphological differences that cause differences in secretion. Since
those physiological or morphological differences might cause or help to
cause a cancer, the non-talc users must be carefully chosen to be
equivalent to the talc users in secretion levels as well, they must not be
merely a random sample of the population.
The most straightforward way to study a problem like this is usually to
identify two comparable populations and follow them for a number of years.
As for peer review in medicine, this does not have quite the effect people
suppose it to have. The classic reference on this is summarized in an
editorial published in the Journal of the American Medical Association in
1966 (p. 167). Although it was 30 years ago, 10 years ago replications
were finding the same and, although I have not specifically looked since
then, I have not noticed that the shape of the universe has changed:
"Medical authors are not apt to submit for publication mauscripts which
contradict facts of human anatomy or flaunt laws of physiology. Extensive
training in the basic sciences and corrective influences of friendly
experts caution them against perpetrating these offenses. Yet, authors of
the same manuscripts are more likely than not to contravene 'anatomy' and
'physiology' of experimental design and statistical 'dissection'. In a
study of 149 articles selected at randeom from ten widely read and highly
regarded medical periodicals, Schor [the AMA's statistical consultant]
and Karten...found [in a study published in the same issue] that less than
28% have sufficient statistical support for drawn conclusions. None of
the remaining 72% could pass muster in terms of experimental design,
applicability of statistical tsts, and the type of analysis performed."
For a non-technical, jargon-free introduction to the problems of medical
research and the peer review thereof, and to the nature of medical
epistomology, see Maurer & Maurer: "The World of the Newborn", p.
237-243, 1988 & 1989, New York (Basic Books) & London (Viking & Penguin).
Unfortunately, although this is available in a number of languages,
English is no longer one of them except at libraries.
Tim Smith
But you didn't address Jobst's point. *Why* don't you want to use tire
irons? I've been using them for years to mount tires, since I have
weak hands (neuropathy). I haven't pinched a tube yet.
That said, your second point might be a function of some tire makers
conservative specs, not a design flaw. No company wants to be sued
because a tire dismounted accidentally. Not sure about this, perhaps
someone knowledgeable about the industry (and willing to share inside
stuff) can inform us?
--Tim (tss...@best.com)
Rick Denney
Jobst wrote
>>>From this I take it you don't use tire levers to mount your tires.
>>>Who started this macho concept of "real bikers don't use tire irons".
>>>I've watched people work their fingers red trying to put on a tire
>>>with tire irons lying right there. You can pinch a tube just as well
>>>by hand, it only takes longer and hurts while your at it.
>>
And Matt O'Toole responded
>>
>>I don't use tire irons if I can avoid it. More specifically, I don't use
>>tires that require tire irons. This is the number one criteria in choosing
>>tires for me. Otherwise, there are good tires from all manufacturers these
>>days, so I choose the ones that are easiest to remove and replace.
>>Michelin mountain bike tires, and all Continentals are just too hard to get
>>off and on. There is no reason for this that I can see, and I consider it a
>>flaw in the design.
And Tim Smith added
>
>But you didn't address Jobst's point. *Why* don't you want to use tire
>irons? I've been using them for years to mount tires, since I have
>weak hands (neuropathy). I haven't pinched a tube yet.
>
>That said, your second point might be a function of some tire makers
>conservative specs, not a design flaw. No company wants to be sued
>because a tire dismounted accidentally. Not sure about this, perhaps
>someone knowledgeable about the industry (and willing to share inside
>stuff) can inform us?
Now, me
If we are to understand the design of hooked beads, the tightness of
the bead during mounting doesn't seem strictly relevant. I agree that
Continentals seem tighter than others, but the only tire in recent
memory that I've mounted poorly enough to blow off the rim upon
inflation was a Conti foldable.
With a hooked bead, the inflation pressure is supposed to force the
interlock between the tire and rim to get tighter.
I agree with Jobst that tire irons in the proper hands are no more
dangerous than bare hands. I don't like them, however, because they
take longer and require more coordination. I'm blessed with large,
strong hands, and rarely have to use tire irons. It's much easier and
faster for me to just pop the tire over the edge of the rim than it is
to mess with a tool. So, from the standpoint of personal preference,
if Matt's hands are strong enough, then his approach seems entirely
reasonable to me.
Rick Denney
Take what you want and leave the rest.
Ray Sachs
Rick Denney wrote:
> I agree with Jobst that tire irons in the proper hands are no more
> dangerous than bare hands. I don't like them, however, because they
> take longer and require more coordination. I'm blessed with large,
> strong hands, and rarely have to use tire irons. It's much easier and
> faster for me to just pop the tire over the edge of the rim than it is
> to mess with a tool. So, from the standpoint of personal preference,
> if Matt's hands are strong enough, then his approach seems entirely
> reasonable to me.
And for those of you without real strong hands, there's a new product
out called the "speed lever" that seems to avoid the pinch flat problem
pretty well. It telescopes and you attach one end to your axle and the
other fits on the rim and spins the tire onto and/or off of the rim.
Because extremely tight Conti road tires are tough to do by hand, I
picked one up the other day and found that it works tremendously on all
but the toughest road tires. Those that would be mildly difficult to
difficult without it go on like buttah with it. Those that are damn near
impossible without it (Conti GP 20mm foldables, for example) still take
work, but noticeably less so that with bare hands. If nothing else, on
the really tough tires, it sort of holds the tire in place, so that as
you make progress, you can apply all of your pressure in one place
without having to worry about it slipping off on the other side of the
rim. It costs about $10 and while my experience is that it won't make
the toughest tires easy, it's the best solution I've found so far.
-Ray
Mike Miller
>
>Jobst Brandt wrote in message <6400pg$6...@hplms2.hpl.hp.com>...
>
>>From this I take it you don't use tire levers to mount your tires.
>>Who started this macho concept of "real bikers don't use tire irons".
>>I've watched people work their fingers red trying to put on a tire
>>with tire irons lying right there. You can pinch a tube just as well
>>by hand, it only takes longer and hurts while your at it.
>
>
>I don't use tire irons if I can avoid it. More specifically, I don't use
>tires that require tire irons. This is the number one criteria in choosing
>tires for me. Otherwise, there are good tires from all manufacturers these
>days, so I choose the ones that are easiest to remove and replace.
>Michelin mountain bike tires, and all Continentals are just too hard to get
>off and on. There is no reason for this that I can see, and I consider it a
>flaw in the design.
Perhaps it is really a feature of the design that you do not yet
understand. Perhaps it is the tires that go on easily, without
tire-irons, that are flawed.
Sometimes when you're in the dark, you see what you want to see.
/m
Ray Bowman
Dated Sat, 08 Nov 1997 15:19:59 -0800
Tom Scarvie <Tom_S...@lbl.gov wrote:
snip
> A talc-believing
>acquaintance of mine has earnestly explained to me that it reduces
>adhesion between tube and casing and therefore makes the tire more
>supple <snip> (and provides) less rolling
>resistance.
I think talc normally has negligible effect on rolling resistance because it is
unlikely to cause tube slip under normal conditions (high air pressure and
tubes that are not highly stretched).
When the tube is stuck to the tire, the repetitive stretching of the tube
material returns most of the additional energy when the material relaxes (such
energy losses are usually termed "hysteresis losses"). This is essentially
no different than what happens with the tire material.
If the tube slips, however, there is direct friction loss, which I beleive
will be larger than the hysteresis loss. However, I know of no direct
measurements or reliable calculations that prove this.
Ray Bowman
Matt O'Toole
Rick Denney wrote...
>Jobst wrote
>>>>From this I take it you don't use tire levers to mount your tires.
>>>>Who started this macho concept of "real bikers don't use tire irons".
>>>>I've watched people work their fingers red trying to put on a tire
>>>>with tire irons lying right there. You can pinch a tube just as well
>>>>by hand, it only takes longer and hurts while your at it.
And I responded...
>>>I don't use tire irons if I can avoid it. More specifically, I don't use
>>>tires that require tire irons. This is the number one criteria in
choosing
>>>tires for me. Otherwise, there are good tires from all manufacturers
these
>>>days, so I choose the ones that are easiest to remove and replace.
>>>Michelin mountain bike tires, and all Continentals are just too hard to
get
>>>off and on. There is no reason for this that I can see, and I consider
it a
>>>flaw in the design.
>And Tim Smith added
>>But you didn't address Jobst's point. *Why* don't you want to use tire
>>irons? I've been using them for years to mount tires, since I have
>>weak hands (neuropathy). I haven't pinched a tube yet.
I have weak hands too, which is why this is so important to me. Some tires
are difficult to mount even with tire levers. Others slip right off and on
with no resistance whatsoever, because they're sized properly to slip over
the rim, and their beads are slim enough to fit into the rim bed.
>>That said, your second point might be a function of some tire makers
>>conservative specs, not a design flaw. No company wants to be sued
>>because a tire dismounted accidentally. Not sure about this, perhaps
>>someone knowledgeable about the industry (and willing to share inside
>>stuff) can inform us?
Outside of plain old sloppy manufacturing tolerances, I suspect that what
they're really trying to do is give an impression of safety. They're trying
to appeal to people who incorrectly believe that tight beads stay on rims
better. It's kind of like how several years ago, car designers would
purposely put big, ugly bumpers on small, family oriented cars, because it
gave buyers a visual impression of safety.
In Europe, bike buyers may be more safety conscious than American ones. It
may be that European made Contis fit tightly to appeal to European consumer
misconceptions about tire safety.
>Now, Rick again...
>If we are to understand the design of hooked beads, the tightness of
>the bead during mounting doesn't seem strictly relevant. I agree that
>Continentals seem tighter than others, but the only tire in recent
>memory that I've mounted poorly enough to blow off the rim upon
>inflation was a Conti foldable.
>With a hooked bead, the inflation pressure is supposed to force the
>interlock between the tire and rim to get tighter.
Don't be so shy about it. We do understand the design of hooked beads, and
they work exactly as you say. The tightness of the bead as it slips over
the rim is indeed irrelevent.
>I agree with Jobst that tire irons in the proper hands are no more
>dangerous than bare hands. I don't like them, however, because they
>take longer and require more coordination. I'm blessed with large,
>strong hands, and rarely have to use tire irons. It's much easier and
>faster for me to just pop the tire over the edge of the rim than it is
>to mess with a tool. So, from the standpoint of personal preference,
>if Matt's hands are strong enough, then his approach seems entirely
>reasonable to me.
I agree on all points here. If tire (and rim) makers would take a little
more care in sizing their bead diameters, mounting and dismounting tires
would be a lot easier, and we wouldn't have to worry about tire levers.
Matt O.
F. Hayashi
speaking of tire irons, has anyone tried the new one that attaches to the
wheel's axle, telescopes, and hooks on to the rim? Apparently, it's
supposed to work like the tire machines they have for auto tires.
A local bike shop owner thinks that they are so good that she believes
that her flat tire repair business is going to disappear.
+---------------------------------------------------------------------+
I Fumitaka Hayashi http://www.geocities.com/capecanaveral/lab/4315 I
I <hay...@u.washington.edu> http://weber.u.washington.edu/~hayashi I
I Aderem Lab - Dept. of Immunology - University of Washington I
+---------------------------------------------------------------------+
Jobst Brandt
Ray Bowman writes:
> I think talc normally has negligible effect on rolling resistance
> because it is unlikely to cause tube slip under normal conditions
> (high air pressure and tubes that are not highly stretched).
Not only is it negligible but it is zero. No manner of powder between
tube and tire is going to improve rolling resistance over a tube that
adheres to the tire casing. If there were motion, this would have
greatly more losses than elastic distortion of the tube replicating
the casing distortions (that are a few 1/1000inch per inch). Scuffing
over granules of powder is definitely a greater loss than stretching.
> When the tube is stuck to the tire, the repetitive stretching of the
> tube material returns most of the additional energy when the
> material relaxes (such energy losses are usually termed "hysteresis
> losses"). This is essentially no different than what happens with
> the tire material.
The point is that these hysteresis losses ARE what rolling resistance
consists of, not scrubbing on the road as is often postulated here.
These losses arise primarily from the tread and tube, and for fine
cord tires, from the inter-ply elastomer of the tire casing. Certain
fabrics also have internal losses because they are slippery between
filaments of the thread and have internal slipping that has losses.
Kevlar is a material that has a greater propensity for this.
> If the tube slips, however, there is direct friction loss, which I
> believe will be larger than the hysteresis loss. However, I know of
> no direct measurements or reliable calculations that prove this.
You could try to describe a slipping model and realize that this does
not work. The inflation pressure to lateral displacement force ratio
is such that you need a fluid lubricant to achieve movement.
Jobst Brandt <jbr...@hpl.hp.com>
Ray Bowman
Earlier Jobst Brandt asked:
>>> Has anyone explained what talcum powder does?
Dave Hamilton replied:
>> The only uses I can think are these. It makes installing the tube
>> easier -- minimizes the risk that the tube will remain twisted or
>> kinked when first inflated. Careful installation will prevent this.
>> But you cannot see inside the tire to know the tube is twisted.
Then Jobst wrote:
>That is a claim I can not reconcile with my own experience and
>watching others mounting a tire or changing a tube. The problem is
>that the tube gets pinched as the final section of tire is popped over
>the rim. Powder has no effect on the tire iron or the position of the
>tube at that time.
I think it is commonly accepted that pinching of the tube usually occurs when
the final section of the bead is popped over, as Jobst has noted. This tube
pinching can be either from getting caught between the bead and rim or from
being snagged by a tire lever. Neither problem is likely to occur if the tube
is slightly inflated and is free to slip to the center of the tire and stay
there. Talc provides enough lubrication to make this centering easy and
reliable.
Dave's second claim, that the tube might remain twisted or kinked, is also
correct. In fact, there is proof that twisted tubes happen, even with proper
mounting technique. In my business, we have done well over a thousand tube
installations while doing extensive testing of flat protection products.
Because we make many punctures and then often examine the tubes when they are
removed, we have observed where the holes in the tube occurred. Sometimes,
particularly when not using talc, the holes in the tube clearly show that the
tube was twisted - that is, the holes might be along the sidewalls or inner
portions of the tube for punctures made in the tread area of the tire.
Tubes twisted in the tire will have more stretch in some areas than they would
if not twisted. This is undesirable but will not normally cause problems.
One exception is when using sealants. A little sealant must always escape
before the hole seals. If the tube is twisted where a puncture occurs, the
lubrication provided by the escaping sealant can allow the twisted tube to
slip into a normal position; and for larger holes this slippage can interfere
with the sealing process.
Ray Bowman
Jobst Brandt
Matt O'Toole writes:
>> From this I take it you don't use tire levers to mount your tires.
>> Who started this macho concept of "real bikers don't use tire
>> irons". I've watched people work their fingers red trying to put
>> on a tire with tire irons lying right there. You can pinch a tube
>> just as well by hand, it only takes longer and hurts while your at it.
> I don't use tire irons if I can avoid it. More specifically, I
> don't use tires that require tire irons. This is the number one
> criteria in choosing tires for me. Otherwise, there are good tires
> from all manufacturers these days, so I choose the ones that are
> easiest to remove and replace.
I think this is a bit extreme. I choose tires for their durability,
good cornering and low rolling resistance. I think these are the
important characteristics on which to choose a tire. I don't use
folding tires because they cost more, are more susceptible to blowing
off the rim under hot braking and are a pain to change. I would
probably use them if they offered an advantage over the wire bead
version of the same tire, but they don't, and because they are more
difficult to mount, I carry one only as a spare on long tours.
What is the appeal of putting on tires without a tire iron? Is this
also a "no pain no gain" sort of thing? I've always changed tires
with tire irons and have been admonished that I shouldn't do so,
because "that's not good". What is it that's not good?
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Fumitaka Hayashi writes:
> Speaking of tire irons, has anyone tried the new one that attaches
> to the wheel's axle, telescopes, and hooks on to the rim?
How well does it fit into a patch kit or jersey pocket?
Jobst Brandt <jbr...@hpl.hp.com>
Matt O'Toole
Jobst Brandt wrote in message <647j00$e...@hplms2.hpl.hp.com>...
>I think this is a bit extreme. I choose tires for their durability,
>good cornering and low rolling resistance. I think these are the
>important characteristics on which to choose a tire.
It would be extreme if I ignored those other factors, as they're important
to me, too. As I mentioned in another post, most major manufacturers offer
tires that perform well enough in those areas. Given that they are
virtually equal performers, I choose the ones that are easiest to get off
and on.
>I don't use
>folding tires because they cost more, are more susceptible to blowing
>off the rim under hot braking and are a pain to change.
Though folding skinny road bike tires are harder to change, it doesn't
usually make a difference with mountain bike tires.
The only problems I've ever had with tires blowing off were because the
beads were too fat and uneven, and wouldn't seat properly on the rim. They
were folding tires, but the problems were due to being poorly made. I'm
interested in knowing why you think folding tires are more likely to blow
off.
>I would
>probably use them if they offered an advantage over the wire bead
>version of the same tire, but they don't, and because they are more
>difficult to mount, I carry one only as a spare on long tours.
With most mountain bike tires, the folding version is usually of much higher
quality overall. This isn't true of all brands, but it is of most. If
there is a good quality wire-bead version, it often isn't widely available.
Shops either sell a super cheap, low quality OEM version, or the most
expensive version possible. There is no sensible middle ground available.
The marketing geniuses see to that.
>What is the appeal of putting on tires without a tire iron? Is this
>also a "no pain no gain" sort of thing? I've always changed tires
>with tire irons and have been admonished that I shouldn't do so,
>because "that's not good". What is it that's not good?
I use tire irons if they're needed. I'm not interested in pain at all.
Given the choice, I'd rather use tires that are really easy to get off and
on. I see no reason why all tires can't be made this way.
Matt O.
Reg_Burgess%AntiSpamPostfix%
In article <647j00$e...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst
> Matt O'Toole writes:
>
> >> From this I take it you don't use tire levers to mount your tires.
> >> Who started this macho concept of "real bikers don't use tire
> >> irons". I've watched people work their fingers red trying to put
> >> on a tire with tire irons lying right there. You can pinch a tube
> >> just as well by hand, it only takes longer and hurts while your at
it.
>
> > I don't use tire irons if I can avoid it. More specifically, I
> > don't use tires that require tire irons. This is the number one
> > criteria in choosing tires for me. Otherwise, there are good tires
> > easiest to remove and replace.
>
> I think this is a bit extreme. I choose tires for their durability,
> good cornering and low rolling resistance. I think these are the
> folding tires because they cost more, are more susceptible to blowing
> probably use them if they offered an advantage over the wire bead
> version of the same tire, but they don't, and because they are more
> difficult to mount, I carry one only as a spare on long tours.
>
> also a "no pain no gain" sort of thing? I've always changed tires
> with tire irons and have been admonished that I shouldn't do so,
> because "that's not good". What is it that's not good?
>
What is "not good" is getting the tire/tube/rim so out of position that
tire irons are needed. If you need that much force it isn't positioned
properly (beads down in the rim opposite the point where you're
finishing). Tire irons then give you the opportunity to apply too much
force to the edge of the rim and/or to nip the tube. If everything is
lined up properly there's no need for red hands or sore fingers. It isn't
a macho or strength THING, its a simple skill THING to get a lightly
inflated tube into the outer casing and get that casing around the rim
with the beads down in the "well" of the rim.
Reg {with small hands for a guy my size, not a lot of strength in them,
but I DO change motorcycle tires "sans levers"}
> Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Reg Burgess writes:
>> What is the appeal of putting on tires without a tire iron? Is this
>> also a "no pain no gain" sort of thing? I've always changed tires
>> with tire irons and have been admonished that I shouldn't do so,
>> because "that's not good". What is it that's not good?
> Oh, not AGAIN !
> What is "not good" is getting the tire/tube/rim so out of position that
> tire irons are needed. If you need that much force it isn't positioned
> properly (beads down in the rim opposite the point where you're
> finishing).
My tires go on without problems and do so quickly. In contrast I see
the manual efforts doing things that I would not like to do several
times in a row, as in the bike shop where the mechanics use tire
levers. I see no reason to do this by hand and know for sure that
some tires cannot be mounted by hand at all.
> Tire irons then give you the opportunity to apply too much
> force to the edge of the rim and/or to nip the tube.
That's your choice to resist that urge. Besides, what is "too much
force" if it puts the tire on the rim swiftly and easily? You are
dodging and weaving. What's wrong with using tire levers?
> If everything is lined up properly there's no need for red hands or
> sore fingers.
I can show you tires that you cannot get on with your hands. If it
were so easy and preferable, I doubt that people who do it for a living
would use tire irons to mount tires.
> It isn't a macho or strength THING, its a simple skill THING to get
> a lightly inflated tube into the outer casing and get that casing
> around the rim with the beads down in the "well" of the rim.
I can only imagine that your road bike has some loose tires. Most
tires that I mount are no snap to put on by hand and those who can't
use a tire iron properly should not try to convince others that
manually is better.
> With small hands for a guy my size, not a lot of strength in them,
> but I DO change motorcycle tires "sans levers".
Certainly not the ones I have mounted. I'm sure you break the bead
loose on car tires by hand too.
Jobst Brandt <jbr...@hpl.hp.com>
F. Hayashi
I finally saw one at the LBS the other day, and it's only about 1.5 times
longer than the normal tire levers that I own. It'll definitely fit a
jersey pocket, and it'll probably fit most seat bags.
I didn't buy it, so I don't know how well it works or how many times you
can use it before you break it.
Anyone buy it yet?
Matt O'Toole
Jobst Brandt wrote in message <648a4f$h...@hplms2.hpl.hp.com>...
>MTB tires have such a large volume that they are relatively
>insensitive to blowoffs. Road tires do this and tandems are a good
>example of how often they do it.
I'm aware of this, though it's never happened to me. What is it about
folding tires that you think makes them more susceptible to blowing off?
>>Given the choice, I'd rather use tires that are really easy to
>> get off and on. I see no reason why all tires can't be made this
>> way.
>I haven't seen many road tires that do that.
Neither have I, but the Specialized ones I used a few years ago were great.
What I'm wondering, is why all tires can't be this easy to deal with. I
haven't owned a road bike in about five years, so I don't know what's
available these days.
Matt O.
jeb
Jobst Brandt wrote:
> It is for these circumstances that I prefer to have the best
> protection. I became aware of the heat problem when we all rode
> tubulars, because I often melted the tires off the rim on many of the
> steep descents around here and in the Alps. I equipped all my tubular
> rims with insulator bands to prevent rolling a tire or shearing the
> stem off.
>
Having never heard of this before, could you describe these insulator bands in a
little more detail, particularly how they are attached to the rim/tire? ( or are
they attached at all? ) Thanks
Jobst Brandt
Matt O'Toole writes:
> It would be extreme if I ignored those other factors, as they're important
> to me, too. As I mentioned in another post, most major manufacturers offer
> tires that perform well enough in those areas. Given that they are
> virtually equal performers, I choose the ones that are easiest to get off
> and on.
I don;t see road tires being equal otherwise so that's why I see it
that way. MTB tires may not make that much difference to you but I
suspect there is a great difference in them too.
>> I don't use folding tires because they cost more, are more
>> susceptible to blowing off the rim under hot braking and are a pain
>> to change.
> Though folding skinny road bike tires are harder to change, it doesn't
> usually make a difference with mountain bike tires.
> The only problems I've ever had with tires blowing off were because the
> beads were too fat and uneven, and wouldn't seat properly on the rim. They
> were folding tires, but the problems were due to being poorly made. I'm
> interested in knowing why you think folding tires are more likely to blow
> off.
MTB tires have such a large volume that they are relatively
insensitive to blowoffs. Road tires do this and tandems are a good
example of how often they do it.
>> I would probably use them if they offered an advantage over the
>> wire bead version of the same tire, but they don't, and because
>> they are more difficult to mount, I carry one only as a spare on
>> long tours.
> With most mountain bike tires, the folding version is usually of much higher
> quality overall. This isn't true of all brands, but it is of most. If
> there is a good quality wire-bead version, it often isn't widely available.
Avocet offers the same quality tires in both versions and the wire
bead tires are both less expensive and easier to mount. As I said, I
carry a spare folding tire on tours, that's about it.
>> What is the appeal of putting on tires without a tire iron? Is this
>> also a "no pain no gain" sort of thing? I've always changed tires
>> with tire irons and have been admonished that I shouldn't do so,
>> because "that's not good". What is it that's not good?
> I use tire irons if they're needed. I'm not interested in pain at
> all. Given the choice, I'd rather use tires that are really easy to
> get off and on. I see no reason why all tires can't be made this
> way.
I haven't seen many road tires that do that.
Jobst Brandt <jbr...@hpl.hp.com>
Tom Ace
Jobst Brandt wrote:
> I can only imagine that your road bike has some loose tires. Most
> tires that I mount are no snap to put on by hand and those who can't
> use a tire iron properly should not try to convince others that
> manually is better.
Which tires are you referring to? I mounted a brand new Avocet
Fasgrip (steel beads, 25 width) on a brand-new Mavic MA-2 (700C)
rim a few days ago, and it went on quite easily without tools.
Tom Ace
cr...@best.com
Jobst Brandt
Matt O'Toole writes:
> I'm aware of this, though it's never happened to me. What is it about
> folding tires that you think makes them more susceptible to blowing off?
The flexibility of the bead makes it easier to locally dislodge it
from its clinch, both because the hoop is not rigid and because the
bead cross section can squirm and change shape, something a steel wire
bead cannot. That is not to say that steel wire beads are immune to
blow-offs.
>>> Given the choice, I'd rather use tires that are really easy to get
>>> off and on. I see no reason why all tires can't be made this way.
>> I haven't seen many road tires that do that.
> Neither have I, but the Specialized ones I used a few years ago were great.
> What I'm wondering, is why all tires can't be this easy to deal with. I
> haven't owned a road bike in about five years, so I don't know what's
> available these days.
I run my tires hard and ride down some steep places where the rims get
extremely hot. In fact, two summers ago I rode down a paved detour in
the mountains that went for several miles at more than 20% grade. I
stopped twice to cool the rims because they were so hot that you could
feel the heat without touching them. I was relieved to not have had a
blowout when I got to the bottom.
It is for these circumstances that I prefer to have the best
protection. I became aware of the heat problem when we all rode
tubulars, because I often melted the tires off the rim on many of the
steep descents around here and in the Alps. I equipped all my tubular
rims with insulator bands to prevent rolling a tire or shearing the
stem off.
Jobst Brandt <jbr...@hpl.hp.com>
David Casseres
There's a lot of variability in the fit of any particular model. I use
Conti SSU 23's on MA-2's, and they are often fairly hard to put on but
sometimes quite easy. I don't use tire irons, but that's only because I
actually find it easier to use my hands to roll the tire onto the rim (I
have large hands).
--
Cheers,
David
Rob Kercher
In article <647ja4$e...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst Brandt) writes:
>From: jbr...@hpl.hp.com (Jobst Brandt)
>Subject: Re: Tire irons, was Re: Cornstarch vs. Talc
>Date: 10 Nov 1997 18:20:52 GMT
>Fumitaka Hayashi writes:
>> Speaking of tire irons, has anyone tried the new one that attaches
>> to the wheel's axle, telescopes, and hooks on to the rim?
>How well does it fit into a patch kit or jersey pocket?
>Jobst Brandt <jbr...@hpl.hp.com>
These are called Speed Levers and they work great. I received one free at
Interbike and IMHO it is the best the show had to offer this year. When I got
home I easily removed a flat tire in literally seconds with no effort. It
wasn't for a few days that I realized if you flip it over it will install a
tire also. It was equally amazing. The Speed Lever is a little longer than a
standard plastic tire iron and weighs about the same as three tire irons so it
will easily fit in your jersey pocket. Since Interbike I have wanted to let
everyone know what a great product it is. Thanks for listening. I am not
affiliated with this company.
Rob Kercher
Mountain Cycling Accessories
Tom Ace
Jobst Brandt wrote:
> I don't see what the desire in
> hand mounting tires is.
As I'd said: I find it easier than using tools. Your mileage may vary.
> The process is reversible. Therefore, they should be removed by hand
> as well I presume. If you carry tire irons, why not use them?
Reversible? Presume? Taking a tire off requires getting the bead
out of the rim, and my fingers don't do that so well. The business
ends of the irons I carry (plastics, actually) are shaped in a way
that is well-suited for pulling the bead out of the rim. They look
to me to be optimized for dismounting, and they do that well.
Tom Ace
cr...@best.com
Jobst Brandt
Tom Ace writes:
> True--but Jobst said he used tires and rims that were typically
> hard to mount without tools, and I was (and still am) curious
> which models he had in mind.
I use Avocet "Road" tires with steel beads and folding ones as a spare
on occasion. I have had tires that did not go on without a bit of
force with levers and they snapped into place with a sharp report. I
have seen others try it without levers and fumble around forever, just
so they can say they did it by hand. I don't see what the desire in
hand mounting tires is.
> This has been my experience as well. Unless a tire is really
> ornery, I find it easier to put it on by hand. (Taking one off is
> another story.)
The process is reversible. Therefore, they should be removed by hand
as well I presume. If you carry tire irons, why not use them? It
certainly isn't faster by hand. I use the lever to push the tube into
place at the closure anyway, so why lay the lever aside and use the
hands. It's similar to a twist-off beer bottle cap that once you have
the bottle opener in your hand, you might as well use it, even though
you just noticed that it is a twist-off.
Jobst Brandt <jbr...@hpl.hp.com>
William Herrera
On Thu, 13 Nov 1997 20:28:09, ste...@apple.com (Stella Hackell) wrote:
> All right, can someone explain how to use tire irons to mount
> the tire *without* puncturing the tube? Please don't say "Be
> careful," because that's not enough IME.
>
Well, having just changed both my son's tires, I can review ny
technique, which uses fingers almost entirely, except for one part I
will asterisk:
1. Deflate tire completely. If it is already flat this one is done for
you.
**2. Put the smooth end of the tire iron, curve facing tire, into the
tire bead and rim on the side opposite the valve.
**3. Using the rim as a fulcrum, pry the iron by rotating it toward
the hub to push the tire off the rim. Secure by hooking the hooked end
on a spoke.
**4. Repeat about ten degrees away along the tire. You now have two
places pried up.
**5. Use the third tire iron to push the tire off the rim further
along, then take off the middle iron and repeat.
6. At some place here the tire will begin to come off easily. Remove
one side from the rim.
7.If Presta, remove valve nut from the valve stem. Pull out the tire.
8. Patch the tube or get out the new one.
9. Check the rim and tire for sharp places and exposed spoke nipples
and cover with tape, etc as needed.
10. Put the new tube in valve first. If presta, replace valve retained
nut (ring shaped) but I leave it a bit loose until later.
11. Inflate the tube a just a little bit, enough so it has a little
bit of roundness. Push into tire.
12. Starting at the valve part of the rim, push the loose tire bead
onto the tire again by pinching the tire sides together. This will
usually get about half the tire on the rim. As you progress, let the
air you put in out, to allow for the pinching procress. The air is
there to keep the tube from twisting inside the tire.
13. With many tires, your hands will fail after a while to make
progress. Wet the tire bead with water; this helps.
**14. If the tire still does not budge, CAREFULLY slip the round end
of the tire iron, concave end down, into the spot on one side where
tire and rim meet. then, leaving it in that position to stop the tire
from slipping on one side of the part of the tire still not on the
rim, really push hard with both hands and thumbs against the tire bead
on the other side, until it pops on. NEVER NEVER pry the iron against
the rim or tube here, just use it as a passive 'stop' to keep the bead
from popping outward. again.
--
The above address is spamblocked.
The real reply-to address is:
william (dot) herrera (at) lookout (dot) com
Jobst Brandt
Stella Hackell writes:
> Can someone explain how to use tire irons to mount the tire
> *without* puncturing the tube?
When the tire is down to the last eight or ten inches of bead still
not on, the tire is usually fairly tight. At this point the tire
lever can be used to push any part of the tube that is not up on the
bed of the rim, up into the tire by shoving the lever up between tire
and rim. Then proceed to lever the tire on. With each 'bite' any
appearance of the tub indicates the prior step was not enough. Repeat
pushing the tube into the tire, away from the interface.
The tube should be partially inflated to put it in place, but once the
tire is being mounted, it should not be inflated. Letting out
pressure will not make it dead flat, but it will have no propensity to
push into places where you don;t want it to be.
The smaller the tube cross section, the easier it is, and I suspect,
that is another reason why people like these weenie tubes that leak
down in a week and go flat in a hurry with the smallest thorn hole. I
prefer the largest tubes that will fit and they cause me no problem in
mounting with tire irons. It requires some skill, but then so do most
things on a bicycle.
Jobst Brandt <jbr...@hpl.hp.com>
Sherman Nip
On 14 Nov 1997 19:04:31 GMT, Garry Lee <gl...@iol.ie> wrote:
>Sent also to net.
>
>Dear Jobst,
>One thing you don't mention, which I find makes a big difference, is to
>sweep the tyre already on into the middle of the rim. This slightly
>loosens the tyre and can make a tyre which is impossible to get on, easy,
>and one which is easy, possible without irons. I learnt this from the net
>and I find it invaluable as on my touring bike I use Conti Top TOuring and
>MA2s a notoriously tight combination
>
Yep, a yeh to Gary,
By "squeezing from the starting point (usually the valve end) with
both hands simultaneously towards the opposite end, the tire in most
cases will pop into place with brute elbow grease!!
Sherman
Garry Lee
Joseph Riel
Stella Hackell writes:
> Can someone explain how to use tire irons to mount the tire
> *without* puncturing the tube?
Jobst explained one method. The one that I use is substantially different.
Rather than levering the tire onto the rim, I run the iron around the
rim, which pulls it onto the rim. The idea is to stick the tool between
the tire and rim, in a section that is already on the rim. The iron
will be pointing away from from the center of the wheel. Now, slide the
tire along the rim. This pulls the tire onto the rim. You can always
see the bottom of the iron, so there is no chance of pinching the tube.
Joe Riel
--
j...@sparc.sandiegoca.ncr.com
TBGibb
In article <stella-ya0231800...@news.apple.com>,
ste...@apple.com (Stella Hackell) writes:
>All right, can someone explain how to use tire irons to mount
>the tire *without* puncturing the tube? Please don't say "Be
>careful," because that's not enough IME.
I think it helps to partially inflate the tube.
Tom Gibb <TBG...@aol.com>
rtj
I worked as a bike mechanic for 7 years about 2 decades ago,
have changed more tires than most people ever will. I
currently mt bike and support about 4 bikes in my family
which is not quite like working in a bike shop but I have
seen a fairly large variety of the current mtb tires.
During this long career, I have run into 2 or 3 tire/wheel
combinations that could not be removed and replaced bare
handed. At least one of the cases, the bead broke when
trying to install it with a tire iron. I do not own and
have never had reason to own tire irons and have seen more
people do damage using them than I care to count. While
they are of some utility to remove tight tires they should
never be used to put one on. I say this because there is
never a need and because there is risk to the tube.
Anyway, the point of all of this is that tire changing is a
matter of technique not tools and I will attempt to explain
how it is done here:
(This is going to be a little long and I am not going to
proof it so please forgive any typos or nonsense sentences)
First remove the tire from the bike and let any remaining
air from the tube.
Take the tire against your hip and wrap your fore arm around
the far side of the tire. With your other hand depress the
valve and squeeze out absolutely as much air as you can by
pressing with your arm and hip.
Place the wheel vertically on the ground with the valve at
the top.
Grab the tire firmly with both hands, one on each side of
the valve squeeze the beads together and push them into the
groove in the center of the rim. Applying constant
downward pressure continue this action until you are most
of the way to the ground.
Flip the wheel up without letting go of the tire. If you
have done it properly you have moved the bead to a smaller
diameter portion of the rim and pulled out the slack. This
should give you a small area where there is enough slack to
lift the tire off of the rim with your thumbs.
If this has not happened you may not have let enough air out
or not succeeded in getting the bead into the groove. Try
it again.
Now, with tire irons you try to pull one side off at a
time. By hand you should just force both side off the side
of the rim. Once both beads are over the side, grab the
tire and push downward to pull the rest out.
You should now have removed the tire.
If you are fixing a flat, and it is not a pinch flat, you
should locate the hole and the cause. The search can be
narrowed by noting the location of the leak in the tube, but
what I do is a quick visual to make sure I am not going to
get cut and then running your fingers around. The inside of
the tire. This is usually faster and more reliable than a
visual inspection. When you find it remove it. Some times
there are other thing in there as well just waiting there
turn. If you do not do this well you will be changing tubes
again soon.
Now for putting the tire back on:
Pump the tube up until it is taunt but not stretched. This
will allow you to place tube in the tire and have it stay
and will prevent twists that can result in lumps in the
tire.
Place the tube in the tire and insert the valve through the
hole in the rim. The tire should be all on one side of the
rim with the valve in the hole. Starting at the valve work
the bead on the side closest to the rim into the channel of
the rim.
You should now have one side of the tire installed the tube
should be in the tire without twists and the other bead
should be fully outside the rim.
Start at the valve and squeeze the bead into the channel.
Using a similar action to removing the tire work the bead
over the edge by using both hands and working evenly away
from the valve. It is important to leave a fair amount of
air in the tube to avoid pinching it.
In most cased the bead will get fairly tight near the end
but because you are working with only one side and because
the bead has not seated, you will usually be able to lift
the bead over the edge pretty easily.
You should now have removed and installed a tire with no
tools.
The last remaining issue is making sure that the bead seats
and that the valve is straight:
It the valve is crooked grasp the tire with one hand and the
rim with the other and slide the tire until it is straight.
If it is tight, let a little air out, but not enough that
the tube looses shape.
Seating the bead can be tricky on new tires but should be
done by pumping the tire up to 50-70% of operating pressure
and looking along the rim for areas that have not popped up
and seated. When you find and area try to lift it into
place with your thumbs. If there is a high area you are in
danger of blowing it out and should let the air out and
recenter the tire and try again.
If you have a sticky hard to seat tire you may need to wet
the rim and tire to lubricate it, but this is usually not
necessary.
Anyway, I probably have gone on long enough. I hope this
helps some of you.
R johnson
David Casseres
> Grab the tire firmly with both hands, one on each side of
> the valve squeeze the beads together and push them into the
> groove in the center of the rim. Applying constant
> downward pressure continue this action until you are most
> of the way to the ground.
In all my years of cycling (about ten) I've never, ever had a rim with a
groove in the center.
> ... you may not have let enough air out
> or not succeeded in getting the bead into the groove. Try
> it again.
Mighty hard, if there's no groove.
> Now, with tire irons you try to pull one side off at a
> time. By hand you should just force both side off the side
> of the rim. Once both beads are over the side, grab the
> tire and push downward to pull the rest out.
Without tire irons, on a rim without a center groove, this just doesn't happen.
> You should now have removed the tire.
Uh huh.
Buycycling Magazine wrote up the same method a year or two ago. I tried
and tried to get a tire off the rim with my bare hands and satisfied
myself that with the tires and rims I use (Conti SSU 700-23 on MA-2 rims)
it is not possible. To make sure, I talked with a couple of friends who
have been serious cyclists far longer than I, and they both said the
article was bullshit. That's good enough for me.
--
Cheers,
David
Joshua_Putnam
>In article <34759709...@ibm.net>, rtj...@ibm.net wrote:
>> Grab the tire firmly with both hands, one on each side of
>> the valve squeeze the beads together and push them into the
>> groove in the center of the rim. Applying constant
>> downward pressure continue this action until you are most
>> of the way to the ground.
>In all my years of cycling (about ten) I've never, ever had a rim with a
>groove in the center.
I suspect he just means the center of the spoke bed, the lowest
part of the rim section that the bead can get into. On an MA-2,
for example, the top of the center of the eyelets is around
4-5mm lower than the bead seat. The drop is deeper on many
mountain bike rims, and on cheap single-wall rims.
>Buycycling Magazine wrote up the same method a year or two ago. I tried
>and tried to get a tire off the rim with my bare hands and satisfied
>myself that with the tires and rims I use (Conti SSU 700-23 on MA-2 rims)
>it is not possible. To make sure, I talked with a couple of friends who
>have been serious cyclists far longer than I, and they both said the
>article was bullshit. That's good enough for me.
I've done it with various road tires on MA-2s and Sun CR-16s,
but it isn't nearly as easy as it sounds, and if I have tire
levers handy I'll certainly use them instead. On a mountain
bike rim with the much deeper center section many rims have,
it's actually pretty easy.
In general, I'd say it's easy to do if the tires are easy to get
*on* without levers, and hard to do if the tires are hard to get
on without levers. In my experience, Contis are in the very
hard to mount without levers category, at least on most narrow
road rims.
--
Jo...@WolfeNet.com is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
"My other bike is a car."
http://www.wolfenet.com/~josh/
rtj
<HTML>
David Casseres wrote:
<BLOCKQUOTE TYPE=CITE>In article <34759709...@ibm.net>, rtj...@ibm.net
wrote:
<P>> Grab the tire firmly with both hands, one on each side of
<BR>> the valve squeeze the beads together and push them into the
<BR>> groove in the center of the rim. Applying constant
<BR>> downward pressure continue this action until you are most
<BR>> of the way to the ground.
<P>In all my years of cycling (about ten) I've never, ever had a rim with
a
<BR>groove in the center.
<P>> ... you may not have let enough air out
<BR>> or not succeeded in getting the bead into the groove. Try
<BR>> it again.
<P>Mighty hard, if there's no groove.
<P>> Now, with tire irons you try to pull one side off at a
<BR>> time. By hand you should just force both side off the side
<BR>> of the rim. Once both beads are over the side, grab the
<BR>> tire and push downward to pull the rest out.
<P>Without tire irons, on a rim without a center groove, this just doesn't
happen.
<P>> You should now have removed the tire.
<P>Uh huh.
<P>Buycycling Magazine wrote up the same method a year or two ago.
I tried
<BR>and tried to get a tire off the rim with my bare hands and satisfied
<BR>myself that with the tires and rims I use (Conti SSU 700-23 on MA-2
rims)
<BR>it is not possible. To make sure, I talked with a couple of friends
who
<BR>have been serious cyclists far longer than I, and they both said the
<BR>article was bullshit. That's good enough for me.
<P>--
<BR>Cheers,
<P>David</BLOCKQUOTE>
Perhaps the word groove is incorrect, however on every rim I have ever
seen, there is a larger diameter lip near the side of the rim that centers
the bead of the tire when said tire is inflated. This may be quite
pronounced as in the case of many simple cross section rims or relatively
small in the case of higher performance rims. I will not say that
there has never been a rim that has been made without this feature, but
there must be some sort of a lower area or the bead will likely break during
your attempt to stretch it during installation. In many cases this
is a relatively small lip and you may not consider it important, but the
effect is multiplied by 2 for each side of the wheel and then by pi for
the circumference for it’s effect on bead length.
<P>I am sorry that you and your friends have been unable to do this.
I will concede again that most of my experience is with bikes that may
have been built before you were born, but I have over the years shown numerous
people how to do this and they and I have used it successfully on hundreds
possibly thousands of tires.
<P>I have seen tire and rim combinations that are difficult to remove and
I ride sewups on my road bike, so I do not have experience with any of
the "modern" high pressure wire ons. Your combination may indeed
be impossible. I was only trying to explain a what how to "possibly"
remove a tire without tire irons and how to avoid many of the reinstallation
problems that people have with twisted tubes, pinch flats, valve failure
and reflatting on the same object. I hope it was of some use.
<P>Anyway best of luck with your tires
<P>rtj
<BR> </HTML>
Garry Lee
I find that with MA2s and Conti TOp Touring, the manoeuvre described turns
nearly impossible into not too difficult with levers.
avag...@gmail.com
Frank Krygowski
> .........dave
>
> http://goo.gl/Nz9LQy
On "The People's Pharmacy" (a syndicated newspaper column, radio show,
website etc) some bicycle tourist recommended original Noxzema cleansing
cream. They claimed thousands of comfortable touring miles.
I've dealt with minor saddle sores on tours. Next time I might try this.
http://www.noxzema.com/products/original-cleansing-cream
--
- Frank Krygowski
avag...@gmail.com
http://webmineral.com/data/Talc.shtml#.VMkzc5V0zm4
there are prescription cleansers for acne...see your dermatologist
John B. Slocomb
long. "Bag Balm" which is highly rated as a saddle cream has Vaseline
and lanolin as its main ingredients (with 0.005% mercury "from
ethylated sterols").
--
Cheers,
John B.
avag...@gmail.com
David Scheidt
:On Wed, 28 Jan 2015 11:37:27 -0500, Frank Krygowski
instead of the mercury compounds. Still works.
--
sig 14
Zarniwoop
> >So we've been told since our first ratty little 20" bikes that whenever we
> >change our tubes, we've got to liberally douse said tubes in talcum
> >powder. I've noted that this has in fact minimized the number of slow
> >flats I've had recently. Okay, given, talc is a Good Thing(tm).
> >
> >But what if talc isn't available?
>
> Talc is a soft, powdery stuff that occurs in nature. The white cliffs
> at Dover, England are talc. The junk that's sold in stores as talcum
> powder is and has been mostly corn starch.
>
> >Today I had to change my tube at work, and couldn't find talc nto save my
> >live. Found some corn starch in the kitchen (god knows where it came
> >from) and user it instead. Seems the same consistency, and as the ancient
> >addage goes, "If I could walk that way..."
>
> Whenever I've had to change a tube away from home, I've noticed that
> the powder is still in the tire from the original installation. Maybe
> I'm using too much!
>
> >So, will corn starch cause my rims to rot and fall of, or my tubes to
> >become HardCord Christian Gumbies, or cars to mysteriously appear from
> >nowhere and kill me? Or is it the fundamental in this case equivalent to
> >talc?
>
> Baby powder or corn starch should work just fine.
>
> FWIW, I don't think the purpose of this powder is to minimize slow
> leaks. I think you put it in the tire so that the tube can wiggle
> around and get straight when you first inflate the tire. It is not
> desireable to have the tube kinked or twisted, but sometimes this
> happens when you insert a tube. The powder prevents this (or, at
> least, minimizes this) from happening.
>
> .........dave
Cornstarch for food ... Talc a Mineral You dust the inside of your tires as you Mount them ,
1 absorbs water and becomes a Paste, the other does Not.
Clive George
> Talc is a soft, powdery stuff that occurs in nature. The white cliffs
> at Dover, England are talc. The junk that's sold in stores as talcum
> powder is and has been mostly corn starch.
carbonate. It fizzes when you put acid on it.
Talc is a silicate, formed from other rocks.
John B. Slocomb
discussion where the makers were said to have stated "we changed to a
new substance because of the furor about mercury", or words to that
effect.
--
Cheers,
John B.
Frank Krygowski
>
> Yup. No one seems to have died from the mercury and I read one
> discussion where the makers were said to have stated "we changed to a
> new substance because of the furor about mercury", or words to that
> effect.
laboratory equipment because it contained some mercury, sealed in a
metal bellows. There was no reasonable way it could leak, and he had
probably been in far more contact with mercury in his career. But he
raised enough of a stink, threatening union action, etc., that we were
instructed to throw the equipment out. We never had the budget to
replace it, so in the end, the students lost a great educational
opportunity because of his fear. Yet there had to have been - and
probably still are - a dozen mercury barometers in the various science labs.
Funny thing was, about the same time as the machinist's kerfuffle we
found an open beaker of mercury, probably 300 mL, that had apparently
been in one of our storage cabinets for years. I called the Health &
Safety officer when I discovered it, expecting that he'd call for the
building to be razed. He walked over personally, took it from my hand,
said "No problem," and walked off with it.
Maybe he sold it to the Bag Balm people?
--
- Frank Krygowski
John B. Slocomb
School the physics "lab" had a mercury barometer - a tall tube sitting
in a little saucer of mercury. Some of us used to drop pennies in the
saucer and reach in and dig them out the next day. we carried them
around to show people our silver penny. As far as I can tell nobody
died from it :-)
I've got a mercury thermometer just outside the window here. Been
there almost as long as we've owned the house. Luckily I don't live in
the U.S. or I'd have to watch out for the Black Helicopters circling
over head :-)
--
Cheers,
John B.
avag...@gmail.com
AMuzi
mercury (negligible to low risk) and organic mercury
compounds (such as methyl and dimethyl mercury, yes can be
dangerous to fatal). For people of a certain age a small
container of metallic mercury salvaged form a broken
thermometer was once a popular plaything with as far as I
can tell no adverse effects.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
John B. Slocomb
doctor when I asked about the dangers of mercury. He stated that one
of the last things a doctor might try for a very severe case of
constipation (just before they cut someone open and manually cleaned
him/her out) was to swallow a cup full of mercury :-) I didn't ask
whether they than got the patient to jump off a stepladder.
--
Cheers,
John B.
Radey Shouman
is not. Mercury metal is volatile at ordinary room temperature.
> Somewhere buried deep in my memory is a statement made by a military
> doctor when I asked about the dangers of mercury. He stated that one
> of the last things a doctor might try for a very severe case of
> constipation (just before they cut someone open and manually cleaned
> him/her out) was to swallow a cup full of mercury :-) I didn't ask
> whether they than got the patient to jump off a stepladder.
in my mouth. Being easily bored, I began chewing on it, and it broke.
It certainly seemed likely that I had swallowed all or most of the
mercury; knowing that mercury was toxic, I was sure that I was going to
die.
Mother called the doctor (at home, in the evening (this was quite a
while ago)). He told her that if I hadn't swallowed any glass there was
nothing to worry about.
I don't recall any unusual laxity of the bowels afterwards.
--
James
>
> Once, when I was a lad, I had a fever, so my mother stuck a thermometer
> in my mouth. Being easily bored, I began chewing on it, and it broke.
> It certainly seemed likely that I had swallowed all or most of the
> mercury; knowing that mercury was toxic, I was sure that I was going to
> die.
>
> Mother called the doctor (at home, in the evening (this was quite a
> while ago)). He told her that if I hadn't swallowed any glass there was
> nothing to worry about.
>
> I don't recall any unusual laxity of the bowels afterwards.
>
>
--
JS
avag...@gmail.com
http://www.medical-library.net/dental_mercury_poisoning.html
The official American Dental Association position on amalgam until recently has been been that not enough mercury is released to pose a hazard -- this despite hard evidence to the contrary. That position has changed in the last few years and the new official position is: no position. They are simply hiding from the issue.
Organic mercury has passed through a living system of some sort and has come out in the chelated form.
The breakage of a mercury thermometer is a potential, although usually unrecognized, medical emergency. Once exposed to air, pure mercury (quicksilver) vaporizes rapidly. If inhaled it makes its way into the tissues of the body in minutes. A large dose can be lethal.
THUS ALZHEIMERS...
Aluminum does a similar dance. Discussing cookware in kayak-canoecamp ect, I recommend MSR stainless then dissed aluminum as toxic with a theoretical basis for Alzheimers.
Egad ! violent objections, the Reynolds Family rose up in protest. I had advanced a commie left wing takeover plot.
AMuzi
few hundred million people drink beer from aluminum cans for
30 years or so. That ought to sort it out, yes?
avag...@gmail.com
bad news Dude. Cans are coated with plastic
http://upload.wikimedia.org/wikipedia/commons/d/d7/SungaLoveScene.jpg
avag...@gmail.com
uh whose sucking what here ?
as with Slocomb the master mechanic, you are humorously pleading mental deficiency from childhood mercury abuse..at both ends.
The skin potion traps bacteria in skin pores and thus is backwards 19thC medicine.
Today, we wash damaged skin with gram negative and positive medical soaps then apply a healing emollient of whatever's recommended.
John B. Slocomb
wrote:
>John B. Slocomb <sloc...@invalid.com> considered Thu, 29 Jan 2015
>that is prescribed for nappy rash in infants, bedsores, acne and
>eczema - Sudocrem.
>It has a base of water, liquid paraffin, paraffin wax and beeswax, and
>contains zinc oxide, various petroleum derivatives and alcohols, and
>lanolin.
>I'm sure an online search would bring up the full ingredients list if
>it's not available wherever you are and you want to try to reproduce
>the formula, but it works rather well, both as a preventative and
>treatment of saddle sores. It's also pretty inexpensive (around 2 GBP
>per 100g, although the smaller containers obviously carry a premium),
>and available in either large tubs for regular use or small tubes for
>carrying on tour.
I used to use a diaper rash cream that apparently had some of the same
ingredients. but it doesn't seem to be sold any more or maybe more
accurately, not sold here.
As for cost, it is noticeable that "things for bicycles" often cost
more than other "things" of the same nature. I recently saw a chain
described as "10 speed bicycle chain (1/2" x 3/32")" for sale at
pennies over US$ 4.00
--
Cheers,
John B.
John B. Slocomb
wrote:
>John B. Slocomb <sloc...@invalid.com> considered Fri, 30 Jan 2015
>I was completely unable to replace the mercury in my set of carburetor
>balancing manometers, after a severe maladjustment sucked it all out
>through an engine.
My God! You should have advised the proper environmental agency about
this and they would have handled things properly to avoid the
contamination of the highways.
>But I used to play with it as a child, and we had it all over the
>place in the labs at school, and used by both students and staff for a
>variety of experiments and demonstrations.
>I never heard of it doing anyone any harm in liquid metallic form.
>I don't think I'd have wanted to breathe anything from the exhaust of
>that motorcycle that sucked my manometers dry though.
As an aside, the sphygmomanometer that the doctor tests your blood
pressure with has mercury in it :-)
--
Cheers,
John B.
avag...@gmail.com
MERCURY IS GOOD FOR YOU
David Scheidt
:10:24:57 +0700 the perfect time to write:
:>On Mon, 02 Feb 2015 22:11:27 +0000, Phil W Lee <ph...@lee-family.me.uk>
:They still have the old sphygmomanometers, sitting on the top shelf
:gathering dust in the phlebotomist's room (which I have to visit far
:too regularly for my liking - I'm on medication which requires
:constant monitoring of my liver function).
I haven't seen a mercury sphygmonanometer in decades. They're all
aneroid or digital.
--
sig 124
John B. Slocomb
wrote:
>They still have the old sphygmomanometers, sitting on the top shelf
>gathering dust in the phlebotomist's room (which I have to visit far
>too regularly for my liking - I'm on medication which requires
>constant monitoring of my liver function).
termed "screening", BP instruments to digital but both my doctors use
an old fashioned sphygmomanometers when THEY take a BP reading. As I
suffer from hypertension and take my BP daily I asked my cardiologist
about that and she tells me that the digital are not as accurate as
the old ones are and that you can often notice things like missed, or
weak pressure, pulse when a human is listening.
--
Cheers,
John B.
Radey Shouman
> wrote:
>
>>John B. Slocomb <sloc...@invalid.com> considered Tue, 03 Feb 2015
>>10:24:57 +0700 the perfect time to write:
>>
>>>On Mon, 02 Feb 2015 22:11:27 +0000, Phil W Lee <ph...@lee-family.me.uk>
>>>wrote:
>>>
>>>As an aside, the sphygmomanometer that the doctor tests your blood
>>>pressure with has mercury in it :-)
>>
>>Not anymore - they've replaced them all with digital ones.
>>They still have the old sphygmomanometers, sitting on the top shelf
>>gathering dust in the phlebotomist's room (which I have to visit far
>>too regularly for my liking - I'm on medication which requires
>>constant monitoring of my liver function).
>
> Nope. The hospitals I go to have both changed the, what might be
> termed "screening", BP instruments to digital but both my doctors use
> an old fashioned sphygmomanometers when THEY take a BP reading. As I
> suffer from hypertension and take my BP daily I asked my cardiologist
> about that and she tells me that the digital are not as accurate as
> the old ones are and that you can often notice things like missed, or
> weak pressure, pulse when a human is listening.
an old fart, and retired a few years ago. The new quack is a young guy
who doesn't even take my blood pressure, he has an office boy do it
using a completely automatic device. I'm not sure anyone in the office
could use an old-fashioned mercury filled instrument on a bet.
I blame the flacks, now that they have won the car vs pedestrian
campaigns they have moved on to medical devices.
--
jbeattie
Not saying you should put on your cornflakes, though.
-- Jay Beattie.