Helium-gas filled frames and tyres, anyone tried it?

[Higgs2011]

I was looking at my bike and it will cost me about a £groupsert and £wheels to get down from 7.5kg to 6.5kg methinks but then I thought Helium-gas is cheap so could I fill all the hollows with it to make my bike lighter? What do you guys think? (there might be some maths involed somewhere I'm sure lol) . . . has anyone thought of this or tried it?

[Karvalo]

Leaving aside the practicalities (or impossibilities) of keeping the helium on the inside, 1 litre of helium is 1 gram lighter than 1 litre of air. How many litres of air do you think are inside your bike?

[Higgs2011]

Leaving aside the practicalities (or impossibilities) of keeping the helium on the inside, 1 litre of helium is 1 gram lighter than 1 litre of air. How many litres of air do you think are inside your bike?

Ahh good, so it's worth doing !!! There must be a way forward.

[BdaGhisallo]

I don't know about helium, but I recall one pro team using nitrogen to inflate their tires. I think it was Telekom, iirc.

[Karvalo]

Not for weight though, it's more or less exactly the same as standard air. It supposedly seeps out ever so slightly slower.

[goodboyr]

Hydrogen is even lighter than helium, and if you're lucky it will give you a rocket powered boost.

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[BdaGhisallo]

Not for weight though, it's more or less exactly the same as standard air. It supposedly seeps out ever so slightly slower.

Exactly - less pressure loss over a day's racing.

[C36]

Eddy Merckx did it for his hour record.
I have a claimed 7g gain on top of my head for the tubulars.
And the molecule being so small, pressure drop is quite faster than with “air”

[Karvalo]

I saw that he wanted to but couldn't? If each tyre contains a litre of air then you'd save around a gram per tyre compared to air for each bar you pressurise them to. 100 psi / 7 Bar would be 7g per tyre, but what did they use on the track those days, somewhere from 10 to 15?

Surely it's a terrible idea though, and the pressure loss and rolling resistance would have made it worse than useless.

[UpFromOne]

Why discuss which gas is best, when you should do away with the material altogether...just vacuum-seal your frame!
Might not be a good idea on the tires though

[uraqt]

nitrogen, was used becasue of the heat ... there is less water in it so it heats up less.. lessing the risk of a tubular glue failing

C

[EtoDemerzel]

Nitrogen has larger molecules and deflates slower than compressed air.
No moisture content, inert gas, and prevents oxidation. Important for airplanes and F1 cars but meaningless for a bike.

Air is 80% nitrogen and bike tires won't last long enough for internal oxidation to matter.
Nitrogen fill is a good profit for service dept's where car owners will pay $200 for an oil change. Usually they even give you a special green valve cap.

[Karvalo]

nitrogen, was used becasue of the heat ... there is less water in it so it heats up less.. lessing the risk of a tubular glue failing

First, we were talking about a track bike. It has no brakes. How hot was it going to get?

Second, is that actually true? The specific heat capacity (amount of energy needed to raise 1g by 1°) of water vapour is nearly twice that of dry air or nitrogen gas. For a given amount of heat energy input, pure water vapour would stay much cooler than dry air/nitrogen gas, and a certain mass of humid air would stay slightly cooler than a certain weight of dry air/nitrogen. Now humid air is also less dense, so there would be less mass inside the tyre to heat but at ISA the difference in density between vapour and dry air is less than the difference in specific heat capacity, so I would assume that on balance humid air heats up ever so slightly slower under the same conditions.

[usr]

nitrogen, was used becasue of the heat ... there is less water in it so it heats up less.. lessing the risk of a tubular glue failing

First, we were talking about a track bike. It has no brakes. How hot was it going to get?

The nitrogen sub thread isn't about the Eddy hour, it's about (perhaps) Team Telekom out on the road:

I don't know about helium, but I recall one pro team using nitrogen to inflate their tires. I think it was Telekom, iirc.

[Karvalo]

nitrogen, was used becasue of the heat ... there is less water in it so it heats up less.. lessing the risk of a tubular glue failing

First, we were talking about a track bike. It has no brakes. How hot was it going to get?

The nitrogen sub thread isn't about the Eddy hour, it's about (perhaps) Team Telekom out on the road:

Ha good point, I had lost track - sorry!

Still though - as I said I think it is (although a neglible effect all things considered) the other way around. Water is one of the best substances in the natural world at absorbing heat energy for a low rise in temperature.