avmech

Goggles and an oxygen mask................

paranoidroadie

@cyccommute, you seem to be knowlegable about inert gas inflation methods. So, what's you opinion on filling tubes with He? Doesnt He have an AMU of 4, making them the smallest of gas particles? Although He may have a greater chance of deflating due to their small size, wouldn't the gas technically be lighter? I have access to 5.5 ultra high pure, electronic grade helium, and always wanted to give it a whirl.

cyccommute 

Helium weighs 0.00018g/ml. Air weighs 0.00128g/ml. A 700x23 tire has a volume of, roughly, 810ml. The gas in a tube filled with He at 110psi would weight 1.17g while the gas in an air filled tube would weigh 8.13g. You'd be saving 7g.

There is another problem with diffusion rate. Assuming all things being equal, the diffusion coefficient of helium is about 3 times that of air. Diffusion is also dependent on the concentration of the gas. You have more moles of He than of air so the diffusion rate actually goes up. You end up losing more gas, faster. Your tire's pressure could be significantly lower by the end of a given event. And the diffusion rate is temperature dependent so the longer the event, the faster the diffusion.

You could find a better way to save 7g.

BobbyG

I will be filling my tires with air from the planet's most polluted cities on the theory that the ash, soot and other particulates will plug any microscopic breaches in the rubber thus preserving tire inflation. But seriously, how well do "slimed" tires hold air?

fietsbob

given the stuff also clogs up the valve , and only works with tiny holes

if you want long air retention, get heavy thick thorn -resistant innertubes..

NB they let you know quickly when under inflated by a big jump in rolling resistance,

But, ! did a 9 month tour with no flat tires, though I did still top up the PSI.

I-Like-To-Bike

I'd recommend that cyclists concerned or worried about this topic, pump their heads full of nitrogen, then they will no longer be considered airheads.

ursle

As I run nitrogen in my auto tires
The advantage is not refilling every two weeks, I run 40psi and rarely have to top up but every 6 month's, it's all(only) about convenience.

btw, 40psi is good for another 1-2 mpg's(over 32psi) and 62+mpg in the summer is smile inducing.

Err, I run helium's on my roller skates
https://www.create-a-skate.com/hejamyeinwhs.html

ThermionicScott 

If you have to refill your car tires every two weeks, something is very wrong, and it has nothing to do with the air.

prathmann

Hydrogen (H2) would be only half as heavy as He so you could save another half gram. But the diffusion rate for either is very high. As cycocommute said, there are much better ways to save a few grams.

paranoidroadie

Some pro cyclist team must have experimented with this at some time. But like you said, it's just a fudgin' waste of time. But it always crossed my mind staring at that ultra pure He. Definitely a good idea on paper.

thnx for the feedback cyccommute

paranoidroadie

No, H2 is heavier than He. The diffusion rate for He would be the fastest because it has the lowest weight/mole as cyccommute stated, Helium weighs 0.00018g/m. I think one mole of H2 =1.008g? Helium finds it's way into every orifice and crevice, under positive pressure. It's an interesting topic, and would make for a cool experiment. However I'll be sticking with good 'ole fashion at-mos-phere air.

ursle

err, I fill my bicycle tires(tufo's) ever other day when I ride daily, because they lost 10-15 lbs, my car tires which at 40lbs without nitrogen are down 2-5 lbs every two weeks, nothing seriously wrong, just the nature of the beast, 6 months vs 2 weeks, I'll take the 6 months.
Try it you'll like it
Don't try it and argue against it if you wish.

I was hoping about feedback about the helium's

fietsbob

<replies in high squeaky voice> what Helium.. ?

I-Like-To-Bike

Is there anything, legal or not, that some pro cyclists or team has not tried to get an edge over the competition?

ursle

Mybad, should have included the reference, just kidding, as I use them frequently for flexion exercise(flexibility)

Err, I run helium's on my roller skates
https://www.create-a-skate.com/hejamyeinwhs.html

ThermionicScott 

You don't get it. I use regular air in my car tires and only need to refill them once or twice a year. Losing 5 psi in a couple of weeks is not just "the nature of the beast", something is wrong with your wheels or tires.

prathmann

The mass of hydrogen (single proton) is 1.008 g/mole, but it's diatomic, so H2 gas has a mass of 2.016 g/mole. But Helium (2 protons and 2 neutrons) has a mass of 4.003 g/mole, so it's about twice as heavy for a given volume and pressure. But, as mentioned, saving the half gram isn't worth it.

tcarl

If they stay up more than four hours, call your doctor.

rydabent

Skidder--------------Pretty much has the whole answer in his reply.

loky1179

As I recall, Eddie B. used helium in the US national team's tires as far back as '78 or '80. Of course, he also introduced them to blood doping (hey, it was legal back then!), so that may have had a larger effect.

It is not possible to overthink this!

dynodonn 

.....and auto racing tires.

ThermionicScott 

He told them that he had pumped up their tires with helium, and it had a psychological effect. That says more about how suggestible racers are than the merits of helium.

loky1179

He WAS a smart coach! The placebo effect is real, might as well take advantage of it. The price is right too.

zonatandem

Why not try to fill the innertubes with water?
G-E-E-Z . . . just get out thee and ride!

prathmann

That's been done as well - for at least two reasons. First is that it can be a useful technique when out of spare tubes and patches and you get a flat due to a small puncture. Water won't leak out of that small hole nearly as fast as air and can be used to get you home or at least to the nearest shop that sells tubes. The second reason I know of is that water-filled tubes were used to evaluate the effect of wheel weight on performance by a cyclist climbing Alpe d'Huez while keeping a fixed wattage output. As expected, the results showed that speed up a steep slope is inversely proportional to the total weight regardless of where it is located.