Lightening the load

As muni tires have been getting increasing fatter (26x2.2, x2.3, even x2.35), I
was wondering…how much of a weight savings would occur if the tires were
filled with helium instead of air? And while you are at it, you could fill
your Camelbak bladder with helium too.


Ted Howe TedLHowe@compuserve.com

Re: Lightening the load

>…how much of a weight savings would occur if the tires were filled with
>helium instead of air?

It would make litle difference to general riding. Losing a few pounds from the
rider may help though.

>And while you are at it, you could fill your Camelbak bladder with helium too.

Only if you want to talk like a chipmunk.

Wayne van Wijk wvanwijk@gil.com.au

Re: Lightening the load

And don’t forget to fill the air seat with helium too.

>From: Ted Howe <74363.116@compuserve.com> As muni tires have been getting
>increasing fatter (26x2.2, x2.3, even x2.35), I was wondering…how much of a
>weight savings would occur if the tires were filled with helium instead of
>air? And while you are at it, you could fill your Camelbak bladder with
>helium too.
>
>–
>Ted Howe TedLHowe@compuserve.com


Get Free Email and Do More On The Web. Visit http://www.msn.com

RE: Lightening the load

Well by my quickie calculations …which sometimes contain errors :

            A 26"x2.3" tire should have an approximate volume of 5.5L, Now
            since air is composed mainly of nitrogen the densities are
            similar and one can assume equivalent for these purposes. Thus a
            tire with 60 PSIG would hold approximately

                            27g of nitrogen or 4 g of helium

A savings of a whole 23g… that’s almost an once.

                            -Jim

P.S.If your willing to risk the chance of explosion you can fill the tire with
hydrogen and save 26 g.

> -----Original Message----- From: Nathan Hoover [SMTP:nathan@paper2net.com]
> Sent: Monday, May 10, 1999 9:30 AM To: unicycling@winternet.com Subject: Re:
> Lightening the load
>
> It’s even better that you think. Lately, we’ve been using the Nokkian
> Gazzaloddi Jr 26 x 2.6" tire. And that’s the Junior! The full sized 24"/26" x
> 3.0" don’t quite fit. The 26" is actually over 28" in diameter!
>
> Certainly these tires are heavier than the smaller ones (quite a bit), but
> it’s mind boggling how much crazier terrain I can ride now! Wide is good.
>
> —Nathan
>
> PS I’ll let some physics person do the math, but I doubt there’s any
> substantial weight savings to be gained by using helium. Now maybe
> hydrogen… :wink:
>
> Ted Howe <74363.116@CompuServe.COM> wrote in message …
> >As muni tires have been getting increasing fatter (26x2.2, x2.3, even x2.35),
> >I was wondering…how much of a weight savings would occur if the tires were
> >filled with helium instead of air? And while you are at it, you could fill
> >your Camelbak bladder with helium too.
> >
> >–
> >Ted Howe TedLHowe@compuserve.com

RE: Lightening the load

The problem here, of course, is that you may WANT to uni on days when gravity is
low, but you NEED to uni on the days when gravity is high. Walking is just too
much trouble.

> -----Original Message----- From: Rick Bissell [SMTP:rick@tridelta.com] Sent:
> Tuesday, May 11, 1999 1:33 AM To: unicycling@winternet.com Subject: Re:
> Lightening the load
>
> One thing you can do is only ride your heavy mountain unicycles on days when
> the gravity is low.
>
> Most TV and Internet weather reports are giving the gravity forecast these
> days, so if you catch it in the morning you can easily plan your activities
> for the day.
>
> I missed the weather this morning, but I can tell the gravity is really high -
> I had a particularly hard time getting out of bed and walking is difficult.
>
> ~rick

Re: Lightening the load

>In article <19990510194923.29315.00002711@ng-cg1.aol.com>, univent@aol.com
>(UniVent) wrote:

>You’d probably save just as much weight (maybe more) by not wearing socks.

or any clothes for that matter.

===============
Wayne van Wijk

President of the nude cross country unicycle association of Australia

Re: Lightening the load

Ted Howe <74363.116@compuserve.com> writes:

> how much of a weight savings would occur if the tires were filled with helium
> instead of air?

You’d lose tire pressure (through leakage) faster with helium.

A rough calculation for a 26" (66cm) tire with cross section diameter of (I’m
guessing here) 2" (~5cm) would have a volume of ~4367cm^3.

You could use the ideal gas law (PV=nRT) to figure out how many helium molecules
would fill that.

Calculating the mass of the air is harder, since it’s such a mix. It would
probably be easier to find an engineering reference table that just tells you
how much 1cm^3 of air weighs at whatever pressure we inflate tires to.

Re: Lightening the load

How much helium is between your ears?

Re: Lightening the load

It’s even better that you think. Lately, we’ve been using the Nokkian Gazzaloddi
Jr 26 x 2.6" tire. And that’s the Junior! The full sized 24"/26" x 3.0" don’t
quite fit. The 26" is actually over 28" in diameter!

Certainly these tires are heavier than the smaller ones (quite a bit), but it’s
mind boggling how much crazier terrain I can ride now! Wide is good.

—Nathan

PS I’ll let some physics person do the math, but I doubt there’s any substantial
weight savings to be gained by using helium. Now maybe hydrogen… :wink:

Ted Howe <74363.116@CompuServe.COM> wrote in message …
>As muni tires have been getting increasing fatter (26x2.2, x2.3, even x2.35), I
>was wondering…how much of a weight savings would occur if the tires were
>filled with helium instead of air? And while you are at it, you could fill
>your Camelbak bladder with helium too.
>
>–
>Ted Howe TedLHowe@compuserve.com

Re: Lightening the load

Or, if you position the shreader valve properly, you can fill it with
methane ;>)

John Childs wrote:
>
> And don’t forget to fill the air seat with helium too.
>
> >From: Ted Howe <74363.116@compuserve.com> As muni tires have been getting
> >increasing fatter (26x2.2, x2.3, even x2.35), I was wondering…how much of a
> >weight savings would occur if the tires were filled with helium instead of
> >air? And while you are at it, you could fill your Camelbak bladder with
> >helium too.
> >
> >–
> >Ted Howe TedLHowe@compuserve.com
>
> _______________________________________________________________
> Get Free Email and Do More On The Web. Visit http://www.msn.com

Re: Lightening the load

Great news for unicyclists who want to “lighten the load”!!!

Dave’s Mobile Sandwich and Surgery Shop is coming to North Bend for the National
Unicycling Convention.

Our latest product is the Titanium Butt Implant. Replace that old tub of lead
with a whole new “Miyata” compatible set of cushions.Our Butt Implant gives “A
Peck on the Cheek” a whole new meaning.

David Maxfield Bainbridge Island, WA

Re: Lightening the load

It would weigh the same because to get the same air pressure you would need a
much larger volume of gas which would probably weigh about the same.

Re: Lightening the load

One thing you can do is only ride your heavy mountain unicycles on days when the
gravity is low.

Most TV and Internet weather reports are giving the gravity forecast these
days, so if you catch it in the morning you can easily plan your activities
for the day.

I missed the weather this morning, but I can tell the gravity is really high - I
had a particularly hard time getting out of bed and walking is difficult.

~rick

Re: Lightening the load

In article <19990510194923.29315.00002711@ng-cg1.aol.com>, univent@aol.com
(UniVent) wrote:
> It would weigh the same because to get the same air pressure you
would need a
> much larger volume of gas which would probably weigh about the same.

Your answer is correct (it would weigh about the same), but your reason is
incorrect.

Gasses obey the equation PV = nRT where: P is pressure, V is volume, n is the
number of molecules, R is a constant, and T is the temperature.

(I’m ignoring the units of measure, because the constant R is chosen to account
for whatever units you happen to prefer.)

The volume is essentially a constant determined by the size of the tire (the
tire may lose a little volume when you put weight on
it). We can ignore the temperature because that doesn’t depend on the gas you
use to fill your tire.

That simplifies the equation to P = nR for tires (R now accounts for pressure
and temperature too). If you want to double the pressure in a tire, you double
the number of molecules. The pressure doesn’t depend on the mass (or weight) of
the gas you use, only the number of molecules.

So helium would weight less than air for any given pressure. (For experimental
proof, blow up two balloons to the same size, use air for one and helium for the
other. Both balloons have the same pressure because the balloon size is the
same, the helium will clearly be lighter.)

However, given the small volume of a tire, the difference in weight would not
be significant. You’d probably save just as much weight (maybe more) by not
wearing socks.

Jim

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