Tires Gradually Go Flat in Storage

[Michael Press]

In article
<[email protected]>,
jim beam <[email protected]> wrote:

> Michael Press wrote:
> > In article <[email protected]>,
> > [email protected] wrote:
> >
> >> Someone writes:
> >>
> >>>>> Has anybody tried filling bicycle tires with nitrogen? Auto tire
> >>>>> dealers are offering a nitrogen fill option claiming less leakdown
> >>>>> due to the larger molecules.Also less pressure variation are less
> >>>>> corrosion on tubeless tire wheels due to absence of water vapor
> >>>>> and oxygen.
> >>>> I am surprised that no one has offered helium tire inflation to the
> >>>> weight-weenie crowd.
> >>> Some pro/national track teams use helium in their tubulars, but the
> >>> very small molecule (actually just an atom) combined with latex
> >>> tubes means pressure loss is too fast to make this practical for
> >>> road bikes used for several hours at a time.
> >>> It has been alleged that the GB track team use much cheaper
> >>> nitrogen, but paint their nitrogen cylinders to make other teams
> >>> think they're using helium.
> >> Hydrogen, although a diatomic element is leakier than helium, a
> >> montomic molecule.
> >>
> >> 2 He, 10 Ne, 18 Ar, 36 Kr, 54 Xe, 86 Rn
> >
> > What is called for is the molecular mass not atomic mass.
> > MM is what governs the diffusion rate.
> >
> > He 4.003
> > Ne 20.18
> > Ar 39.95
> > Kr 83.80
> > Xe 131.3
> > Ra 226
> >
> > (Do not worry about the decimal places.)
> > Molecular mass of H2 is 2.
> > This gives He a diffusion rate 0.7 times
> > that of H2.
>
> yeahbut, the molecular size of H2 is much larger than the atomic size of
> He. that also affects diffusion rate.

How big is the H2 molecule,
and how big is the He atom?

--
Michael Press

 

[jim beam]

Michael Press wrote:
> In article
> <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> Michael Press wrote:
>>> In article <[email protected]>,
>>> [email protected] wrote:
>>>
>>>> Someone writes:
>>>>
>>>>>>> Has anybody tried filling bicycle tires with nitrogen? Auto tire
>>>>>>> dealers are offering a nitrogen fill option claiming less leakdown
>>>>>>> due to the larger molecules.Also less pressure variation are less
>>>>>>> corrosion on tubeless tire wheels due to absence of water vapor
>>>>>>> and oxygen.
>>>>>> I am surprised that no one has offered helium tire inflation to the
>>>>>> weight-weenie crowd.
>>>>> Some pro/national track teams use helium in their tubulars, but the
>>>>> very small molecule (actually just an atom) combined with latex
>>>>> tubes means pressure loss is too fast to make this practical for
>>>>> road bikes used for several hours at a time.
>>>>> It has been alleged that the GB track team use much cheaper
>>>>> nitrogen, but paint their nitrogen cylinders to make other teams
>>>>> think they're using helium.
>>>> Hydrogen, although a diatomic element is leakier than helium, a
>>>> montomic molecule.
>>>>
>>>> 2 He, 10 Ne, 18 Ar, 36 Kr, 54 Xe, 86 Rn
>>> What is called for is the molecular mass not atomic mass.
>>> MM is what governs the diffusion rate.
>>>
>>> He 4.003
>>> Ne 20.18
>>> Ar 39.95
>>> Kr 83.80
>>> Xe 131.3
>>> Ra 226
>>>
>>> (Do not worry about the decimal places.)
>>> Molecular mass of H2 is 2.
>>> This gives He a diffusion rate 0.7 times
>>> that of H2.
>> yeahbut, the molecular size of H2 is much larger than the atomic size of
>> He. that also affects diffusion rate.
>
> How big is the H2 molecule,

http://en.wikipedia.org/wiki/Molecule#Molecular_size

> and how big is the He atom?

http://en.wikipedia.org/wiki/Helium

>

 

[Michael Press]

In article
<[email protected]>,
jim beam <[email protected]> wrote:

> Michael Press wrote:
> > In article
> > <[email protected]>,
> > jim beam <[email protected]> wrote:
> >
> >> Michael Press wrote:
> >>> In article <[email protected]>,
> >>> [email protected] wrote:
> >>>
> >>>> Someone writes:
> >>>>
> >>>>>>> Has anybody tried filling bicycle tires with nitrogen? Auto tire
> >>>>>>> dealers are offering a nitrogen fill option claiming less leakdown
> >>>>>>> due to the larger molecules.Also less pressure variation are less
> >>>>>>> corrosion on tubeless tire wheels due to absence of water vapor
> >>>>>>> and oxygen.
> >>>>>> I am surprised that no one has offered helium tire inflation to the
> >>>>>> weight-weenie crowd.
> >>>>> Some pro/national track teams use helium in their tubulars, but the
> >>>>> very small molecule (actually just an atom) combined with latex
> >>>>> tubes means pressure loss is too fast to make this practical for
> >>>>> road bikes used for several hours at a time.
> >>>>> It has been alleged that the GB track team use much cheaper
> >>>>> nitrogen, but paint their nitrogen cylinders to make other teams
> >>>>> think they're using helium.
> >>>> Hydrogen, although a diatomic element is leakier than helium, a
> >>>> montomic molecule.
> >>>>
> >>>> 2 He, 10 Ne, 18 Ar, 36 Kr, 54 Xe, 86 Rn
> >>> What is called for is the molecular mass not atomic mass.
> >>> MM is what governs the diffusion rate.
> >>>
> >>> He 4.003
> >>> Ne 20.18
> >>> Ar 39.95
> >>> Kr 83.80
> >>> Xe 131.3
> >>> Ra 226
> >>>
> >>> (Do not worry about the decimal places.)
> >>> Molecular mass of H2 is 2.
> >>> This gives He a diffusion rate 0.7 times
> >>> that of H2.
> >> yeahbut, the molecular size of H2 is much larger than the atomic size of
> >> He. that also affects diffusion rate.
> >
> > How big is the H2 molecule,
>
> http://en.wikipedia.org/wiki/Molecule#Molecular_size
>
> > and how big is the He atom?
>
> http://en.wikipedia.org/wiki/Helium

So, how big are they?

--
Michael Press

 

[Joe Riel]

[email protected] writes:

> A rubber inner-tube filled with water, on the other hand, is going to
> be squishing a lot of water around as it rolls, and the mass of the
> water will be swirling uselessly, so there will be more drag.

The two times I had to do this, I cannot say I noticed any difference
in drag. Or otherwise. This was on the Moulton, which has full
suspension, so that would have masked some of the effects.

--
Joe Riel

 

[Joe Riel]

[email protected] writes:

> A rubber inner-tube filled with water, on the other hand, is going to
> be squishing a lot of water around as it rolls, and the mass of the
> water will be swirling uselessly, so there will be more drag.

The two times I had to do this, I cannot say I noticed any difference
in drag. Or otherwise. This was on the Moulton, which has full
suspension, so that would have masked some of the effects.

--
Joe Riel

 

[[email protected]]

On Wed, 31 Oct 2007 08:09:20 -0700, Joe Riel <[email protected]> wrote:

>[email protected] writes:
>
>> A rubber inner-tube filled with water, on the other hand, is going to
>> be squishing a lot of water around as it rolls, and the mass of the
>> water will be swirling uselessly, so there will be more drag.
>
>The two times I had to do this, I cannot say I noticed any difference
>in drag. Or otherwise. This was on the Moulton, which has full
>suspension, so that would have masked some of the effects.

Dear Joe,

Interesting--I just fooled around with a calculator a bit to see what
the practical effect might be.

Even a large increase in rolling resistance will barely show up in the
top speed recorded coasting downhill on a good cyclocomputer,
according to this calculator:

http://austinimage.com/bp/velocityN/velocity.html

If you zero watts and roll both bikes down the same -6% grade, they
reach 53.775 km/h.

Raise the rolling resistance 50% from 0.0050 to 0.0075, and the bike
with squashier tires drops to 52.539 km/h, only 1.236 km/h slower,
about a 2% speed change. In other words, the top coasting speed would
drop to 28.37 mph from 29.04 mph, a difference that no one is likely
to notice without the help of microchips.

For a 10% speed change down that hill, you need to raise the rolling
resistance to about three times the original 0.0050, up to about
0.0150--and that's still just dropping about 3 mph from about 30 mph.

I'm trying to resist the urge to fill a spare front wheel with water
and roll down my daily highway descent a few times.

Cheers,

Carl Fogel

 

[Kerry Montgomery]

<[email protected]> wrote in message
news:[email protected]...
> On Wed, 31 Oct 2007 08:09:20 -0700, Joe Riel <[email protected]> wrote:
>
>>[email protected] writes:
>>
>>> A rubber inner-tube filled with water, on the other hand, is going to
>>> be squishing a lot of water around as it rolls, and the mass of the
>>> water will be swirling uselessly, so there will be more drag.
>>
>>The two times I had to do this, I cannot say I noticed any difference
>>in drag. Or otherwise. This was on the Moulton, which has full
>>suspension, so that would have masked some of the effects.
>
> Dear Joe,
>
> Interesting--I just fooled around with a calculator a bit to see what
> the practical effect might be.
>
> Even a large increase in rolling resistance will barely show up in the
> top speed recorded coasting downhill on a good cyclocomputer,
> according to this calculator:
>
> http://austinimage.com/bp/velocityN/velocity.html
>
> If you zero watts and roll both bikes down the same -6% grade, they
> reach 53.775 km/h.
>
> Raise the rolling resistance 50% from 0.0050 to 0.0075, and the bike
> with squashier tires drops to 52.539 km/h, only 1.236 km/h slower,
> about a 2% speed change. In other words, the top coasting speed would
> drop to 28.37 mph from 29.04 mph, a difference that no one is likely
> to notice without the help of microchips.
>
> For a 10% speed change down that hill, you need to raise the rolling
> resistance to about three times the original 0.0050, up to about
> 0.0150--and that's still just dropping about 3 mph from about 30 mph.
>
> I'm trying to resist the urge to fill a spare front wheel with water
> and roll down my daily highway descent a few times.
>

Carl,
I thought you might be resisting the urge to completely fill both your tires
with Slime and see how they deal with the goatheads!
Kerry

 

[[email protected]]

Joe Riel writes:

>> A rubber inner-tube filled with water, on the other hand, is going
>> to be squishing a lot of water around as it rolls, and the mass of
>> the water will be swirling uselessly, so there will be more drag.

> The two times I had to do this, I cannot say I noticed any
> difference in drag. Or otherwise. This was on the Moulton, which
> has full suspension, so that would have masked some of the effects.

There is little motion in the fluid in a tire because it only changes
shape slightly at the contact area. It is not pumping. I filled my
front tire with water to test the concept that shimmy is affected by
the mass of the wheel. It had no effect on shimmy nor could I feel
that it was full of water while riding.

Jobst Brandt

 

[[email protected]]

Carl Fogel writes:

>>> A rubber inner-tube filled with water, on the other hand, is going to
>>> be squishing a lot of water around as it rolls, and the mass of the
>>> water will be swirling uselessly, so there will be more drag.

>> The two times I had to do this, I cannot say I noticed any
>> difference in drag. Or otherwise. This was on the Moulton, which
>> has full suspension, so that would have masked some of the effects.

> Interesting--I just fooled around with a calculator a bit to see
> what the practical effect might be.

> Even a large increase in rolling resistance will barely show up in
> the top speed recorded coasting downhill on a good cyclocomputer,
> according to this calculator:

http://austinimage.com/bp/velocityN/velocity.html

> If you zero watts and roll both bikes down the same -6% grade, they
> reach 53.775 km/h.

> Raise the rolling resistance 50% from 0.0050 to 0.0075, and the bike
> with squashier tires drops to 52.539 km/h, only 1.236 km/h slower,
> about a 2% speed change. In other words, the top coasting speed
> would drop to 28.37 mph from 29.04 mph, a difference that no one is
> likely to notice without the help of microchips.

> For a 10% speed change down that hill, you need to raise the rolling
> resistance to about three times the original 0.0050, up to about
> 0.0150--and that's still just dropping about 3 mph from about 30
> mph.

> I'm trying to resist the urge to fill a spare front wheel with water
> and roll down my daily highway descent a few times.

When you do that, make sure to let all the air out as the tire gets
near full. With the valve at the top and press down on the tire flat
against the inflation stem so there is no higher space for the air to
rise above the water. Pushing down on the WHEEL in this position
should ultimately squirt only water out of the Presta valve. Then
fill the tire the rest of the way to full.

I used my Silca frame fit pump for that task because it is easy to
fill with water and has a large enough volume to make it a relatively
quick job. It doesn't take nearly as many strokes as filling the tire
with air.

Jobst Brandt

 

[Joe Riel]

[email protected] writes:

> I'm trying to resist the urge to fill a spare front wheel with water
> and roll down my daily highway descent a few times.

The fun part is coming up with a technique for completely filling the
tube with water, that is, removing all the air. It's a bit tricky,
since the valve is on the inner circumference of the torus, so there
is no location that forces the air to the valve.

One strategy---only practical in the lab---is to first roll the tube
up, forcing out all the air, and then close the valve. Insert tube in
tire, mount on rim (a bit of a pain since the tube has no air) and
then submerge part of the wheel with the valve, open it, connect pump,
then fill it up. That should ensure a minimal amount of air.

In the field, I didn't worry about it.

--
Joe Riel

 

[Joe Riel]

[email protected] writes:

>> I'm trying to resist the urge to fill a spare front wheel with water
>> and roll down my daily highway descent a few times.
>
> When you do that, make sure to let all the air out as the tire gets
> near full. With the valve at the top and press down on the tire flat
> against the inflation stem so there is no higher space for the air to
> rise above the water. Pushing down on the WHEEL in this position
> should ultimately squirt only water out of the Presta valve. Then
> fill the tire the rest of the way to full.

Nice tip, I hadn't thought of that.

> I used my Silca frame fit pump for that task because it is easy to
> fill with water and has a large enough volume to make it a relatively
> quick job. It doesn't take nearly as many strokes as filling the tire
> with air.

--
Joe Riel

 

[Tom Sherman]

[email protected] aka Jobst Brandt wrote:
> Mike Fee writes:
>
>>>> By the way, moist air is lighter than dry air.
>
>>> So if you don't have hydrogen or helium available, always fill your
>>> tires on a humid day.
>
>> Better still - just _fill_ the suckers with water. Provides a nice
>> hard ride with the added benefit of being able to find leaks
>> instantly by observing the spurt of water squirting out through the
>> smallest of pin-hole.
>
> Not to laugh, filling a tire with water works well and isn't as hard
> as you think. The only problem is that the tire is heavier. If you
> have a slow leak and nothing with which to fix it on the road, fill
> the tire with water. I've done it and it works like a charm. Of
> course you have to have a good frame fit pump (long stroke Silca) that
> can be filled with water. Make sure to let out all remaining air so
> the water doesn't slosh around.

I thought Jobst preferred milk to water? See
<http://groups.google.com/group/rec.bicycles.tech/msg/c1a9f571ffd02438?dmode=source>.

--
Tom Sherman - Holstein-Friesland Bovinia
When did ignorance of biology become a "family value"?

 

[Leo Lichtman]

"Michael Press" wrote: (clip)Publish the numbers and
> cite your references as others do.
^^^^^^^^^^^^^^^^^
A hydrogen atom consists of one proton in the nucleus, with one electron
orbiting around it. A hydrogen molecule consists of a pair of hydrogen
atoms which complete their electron shells by sharing their electrons. A
helium atom consists of a nucleus with two protons, and two electrons
orbiting around it. Thus, they have the same molecular weight, but the
hydrogen molecule is approximately twice as large, because the protons are
not together in the same nucleus. The actual sizes do not need to be known
for this to be understood.

 

[Leo Lichtman]

"Tom Sherman" wrote: When did ignorance of biology become a "family
value"?
^^^^^^^^^^^^^^^^^^
When the pro-life people started hi-jacking our science teaching.

 

[Michael Press]

In article
<[email protected]
et>,
"Leo Lichtman" <[email protected]> wrote:

> "Michael Press" wrote: (clip)Publish the numbers and
> > cite your references as others do.
> ^^^^^^^^^^^^^^^^^
> A hydrogen atom consists of one proton in the nucleus, with one electron
> orbiting around it. A hydrogen molecule consists of a pair of hydrogen
> atoms which complete their electron shells by sharing their electrons. A
> helium atom consists of a nucleus with two protons, and two electrons
> orbiting around it. Thus, they have the same molecular weight, but the
> hydrogen molecule is approximately twice as large, because the protons are
> not together in the same nucleus. The actual sizes do not need to be known
> for this to be understood.

Will _you_ publish some numbers.

In article
<[email protected]>,
jim beam <[email protected]> wrote:

> yeahbut, the molecular size of H2 is much larger than the atomic size of
> He. that also affects diffusion rate.

What are the sizes? What is "much larger"?

--
Michael Press

 

[Bill Sornson]

Leo Lichtman wrote:
> "Tom Sherman" wrote: When did ignorance of biology become a "family
> value"?
> ^^^^^^^^^^^^^^^^^^
> When the pro-life people started hi-jacking our science teaching.

ROTFL

 

[jim beam]

Michael Press wrote:
> In article
> <[email protected]
> et>,
> "Leo Lichtman" <[email protected]> wrote:
>
>> "Michael Press" wrote: (clip)Publish the numbers and
>>> cite your references as others do.
>> ^^^^^^^^^^^^^^^^^
>> A hydrogen atom consists of one proton in the nucleus, with one electron
>> orbiting around it. A hydrogen molecule consists of a pair of hydrogen
>> atoms which complete their electron shells by sharing their electrons. A
>> helium atom consists of a nucleus with two protons, and two electrons
>> orbiting around it. Thus, they have the same molecular weight, but the
>> hydrogen molecule is approximately twice as large, because the protons are
>> not together in the same nucleus. The actual sizes do not need to be known
>> for this to be understood.
>
> Will _you_ publish some numbers.
>
> In article
> <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> yeahbut, the molecular size of H2 is much larger than the atomic size of
>> He. that also affects diffusion rate.
>
> What are the sizes? What is "much larger"?
>

what's the matter michael? is your web browser broken?

 

[_]

On Wed, 31 Oct 2007 22:50:56 -0700, jim beam wrote:

>
> er, why would my answers are any different from published data?

Yup.

Why would they...

 

[Ben C]

On 2007-11-01, jim beam <[email protected]> wrote:
> Michael Press wrote:
[...]
>> What are the sizes? What is "much larger"?
>>
>
> what's the matter michael? is your web browser broken?

According to http://en.wikipedia.org/wiki/Molecule#Molecular_size, H2 is
the smallest diatomic molecule and is roughly 1.48 Angstroms in length.
That's about 0.15nm.

As for a Helium atom, this page:
http://zebu.uoregon.edu/~soper/Sun/step0.html says it's 10-10m, which is
0.1nm.

So not much difference in size at all.

 

[_]

On Thu, 01 Nov 2007 04:44:55 -0500, Ben C wrote:

> On 2007-11-01, jim beam <[email protected]> wrote:
>> Michael Press wrote:
> [...]
>>> What are the sizes? What is "much larger"?
>>>
>>
>> what's the matter michael? is your web browser broken?
>
> According to http://en.wikipedia.org/wiki/Molecule#Molecular_size, H2 is
> the smallest diatomic molecule and is roughly 1.48 Angstroms in length.
> That's about 0.15nm.
>
> As for a Helium atom, this page:
> http://zebu.uoregon.edu/~soper/Sun/step0.html says it's 10-10m, which is
> 0.1nm.
>
> So not much difference in size at all.

Yes, but what size are they in jim beam's world?