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txt2007

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I've just been thinking about ways to make your bike lighter since everyone seems to be going through great deals to get around 8kg would helium instead of normal air work for inside the tyres preasure sealed so making the bike tubless like moto trials and my other idea (also involving helium) was to insert (not sure how) helium filled ballons into the frame.

Also would foam be better instead of the old inner tube? i run foam in my enduro bike would save you from punctures but would make swapping and all that less frequent... what do you think?

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:P

I'm not accually bothered about doing it myself but it would ever so slightly change the weight wouldnt it?

It would, but it'd be lighter if you ran less pressure in your tyre too. Just put helium in your frame, and bleed your brakes with it too.

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You wouldnt really be able to fill the frame with helium would be a pain sealing it but it could be done i supose, but it would actually make it lighter, not sure by how much though. ANd also because its helium it wont mean youll get more hang time in the air on a gap so you can go bigger its been tryed with footballs and dismissed as being true.

Edited by basher
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You wouldnt really be able to fill the frame with helium would be a pain sealing it but it could be done i supose, but it would actually make it lighter, not sure by how much though. ANd also because its helium it wont mean youll get more hang time in the air on a gap so you can go bigger its been tryed with footballs and dismissed as being true.

biometrics.serendipityThumb.jpg

i wasnt expecting the bike to be able to float with huge insane hang time maybe a little under 7kg maybe?

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I've just been thinking about ways to make your bike lighter since everyone seems to be going through great deals to get around 8kg would helium instead of normal air work for inside the tyres preasure sealed so making the bike tubless like moto trials

No.

my other idea (also involving helium) was to insert (not sure how) helium filled ballons into the frame.

I don't know about you, but I've seen babies being capable of holding helium balloons down. If that's the case, how much of a lift do you think a helium balloon's going to have on a 10kg trials bike? Nothing...

Also would foam be better instead of the old inner tube? i run foam in my enduro bike would save you from punctures but would make swapping and all that less frequent... what do you think?

Heavier, more rotational weight, wouldn't have the same 'feel' as air does normally in tyres. So yeah, no.

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to get any lift from helium, you would have to put a high concentration in the only way to do that would be compressing it all in, lots in would surely require thicker frame material to contain it, hence extra weight.

So that plan has gone shit out then.

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Heavier, more rotational weight, wouldn't have the same 'feel' as air does normally in tyres. So yeah, no.

it's not that bad an idea, if someone would design something similar to the thing used on the inside of a rally cars tyre it would help prevent snake bites and impact punctures it wouldn't stop thorns etc but who really cares about them.

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By the time you've compressed it all enough to have any beneficial effects, the gas itself would weight more than the standard air, but obviously in an ideal world where it doesn't leak etc, the helium would be lifting itself too when you'd found a point of equilibrium to effectively make the bike 'weightless'

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I thought this thread would die ages ago - seems to have a mix of people taking the piss and a couple actually believing what's been said...

Some clarification:

1. Helium is a inert gas, a welder will not ignite it (Helium weighs twice as much as a H2 (Hydrogen) molecule, but is currently used in preference to Hydrogen for balloons and lighter than air vehicles because of its inertness).

2. A tyre filled with Helium will lose pressure about 2.5 times as quickly as one filled with air according to Graham's law. It will feel exactly the same in terms of bounciness though.

3. To work out the weight saving, consider that 1 mole (6.02x10^23 molecules) of air at atmospheric pressure and 25 degC occupies 24.47 litres and weighs 23.97 grammes, 24.47 litres of Helium will weigh 4.003 g. At 30 psi (About 2 Atmospheres gauge, or 3 atmospheres absolute pressure) your tyres will contain 3 times the mass of gas they would contain if they were just at atmospheric pressure. The volume of all the tubes of your frame plus 3 times the volume of both tyres probably comes in around the 24 litre mark, so your weight saving switching to He will be about 20g.

4. Sealing your frame and evacuating all the air from it will save more weight than filling with Helium, but this is still negligible compared to the weight saving possible if you just ride trials naked...

Edited by psycholist
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to get any lift from helium, you would have to put a high concentration in the only way to do that would be compressing it all in, lots in would surely require thicker frame material to contain it, hence extra weight.

Huh, :blink:

As a chemist that dose not make any sense, helium is lighter because is has a lower relative atomic mass of 4, were as air (mostly nitrogen is RAM is 14). Ok, baring that in mind, when you concentrate things in a given volume there is more of the thing being concentrated; ok so there would be more moles (unit of amount of substance) so concentrating it would make it heavier as there would be more of it in an area. For example dense air drops where as lese dense air rises.

So concentrated helium would be heavier than normal pressure of helium, just though i would clear this up before every one get some crazy ideas, soz if ive put all you on a downer, or boaring you but you should know what’s correct. :)

max

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Huh, :blink:

As a chemist that dose not make any sense, helium is lighter because is has a lower relative atomic mass of 4, were as air (mostly nitrogen is RAM is 14). Ok, baring that in mind, when you concentrate things in a given volume there is more of the thing being concentrated; ok so there would be more moles (unit of amount of substance) so concentrating it would make it heavier as there would be more of it in an area. For example dense air drops where as lese dense air rises.

So concentrated helium would be heavier than normal pressure of helium, just though i would clear this up before every one get some crazy ideas, soz if ive put all you on a downer, or boaring you but you should know what's correct. :)

max

to get the bike in to a state of weightlessness, you could tie lots of balloons with helium to the bike, if it was inside the tubing, you would have to compress it to fit it all in, this would need chunckier tubes to hold it. i havent really thought it through, thats just my initial thoughts...

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