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HDTboy
28th March 2006, 13:18
Can anybody see any obvious problems with filling ones tyres with Helium? Other than the cost

justsomeguy
28th March 2006, 13:20
How much weight will that save?

SimJen
28th March 2006, 13:27
Race teams use Nitrogen because it keeps a more stable pressure than Helium.

bugjuice
28th March 2006, 13:28
not a lot..
I thought they use Nitrogen (http://www.kstatecollegian.com/article.php?a=7252) or something else.. that cold stuff, I thought..

reducing unsprung weight would be things like magnesium, titanium or cabon fibre wheels, all of which are fragile to curbs and the like..

you could always just try a diet, tubby

WRT
28th March 2006, 13:32
Besides, your still not reducing the mass. Sure, filling the tyres with helium will make them lighter in relation to gravity, but will it really have an effect on how quickly the suspension moves in relation to the road and the bike? Someone with an engineering degree might be able to confirm or deny, but in my laymans train of thought, I cant actually see it having any difference what so ever.

skelstar
28th March 2006, 13:34
Did I hear that Helium will leak out of a rubber tyre wall due it being smaller in particle dimenisions (compared to air that is)?

svs
28th March 2006, 13:34
won't save you much weight. probably not worth it

Some race teams use nitrogen, but that's mainly for consistency with no contaminants from the air and consistant humidity etc. which means there is less variation in tyre pressure when it heats up, and partly cos sometimes it's easier to carry a nitrogen tank than a compressor.

Me, I'll stick with with plain old air, I doubt my gauge is accurate enough to notice the difference anyway.

Oh and helium diffuses very rapidly through rubbery materials -- the cause
of the short life of helium filled party balloons

SimJen
28th March 2006, 13:41
Carbon or Superlite magnesium wheels will make a far bigger difference.
I gather you've already tried making the bike lighter in other areas? if you haven't then why are you bothered.

Make the fairings from only a few layers of FG
Only put the thinnest coat of paint on
Make sure you take a good dump before riding
Fill your lungs with Helium, it will also make you lighter albeit squeeky
Remove the lights/indicators
Put a lightweight full system on
etc

sAsLEX
28th March 2006, 15:15
Besides, your still not reducing the mass. Sure, filling the tyres with helium will make them lighter in relation to gravity, but will it really have an effect on how quickly the suspension moves in relation to the road and the bike? Someone with an engineering degree might be able to confirm or deny, but in my laymans train of thought, I cant actually see it having any difference what so ever.

a box of helium weighs say 1kg and a box or air weighs say 2 kg, now you tell me if there is a difference trying to swing them about

bugjuice
28th March 2006, 15:17
how would you stop the helium escaping out the box? It's bad enough just trying to keep air in it..

The Stranger
28th March 2006, 15:21
Remove the brakes, all those heavy discs and calipers can't be good for unsprung weight.

froggyfrenchman
28th March 2006, 15:22
Did I hear that Helium will leak out of a rubber tyre wall due it being smaller in particle dimenisions (compared to air that is)?

As far as i know, you are right

HDTboy
28th March 2006, 15:32
a box of helium weighs say 1kg and a box or air weighs say 2 kg, now you tell me if there is a difference trying to swing them about
saslex is following my train of thought.

I'm aware of the use of Nitrogen for stability, the Helium thought was because it's a shitload cheaper than aftermarket wheels


Remove the brakes, all those heavy discs and calipers can't be good for unsprung weight.
True, that's why we have alloy callipers and disc hats

SixPackBack
28th March 2006, 16:46
Did I hear that Helium will leak out of a rubber tyre wall due it being smaller in particle dimenisions (compared to air that is)?

Disregarding other aspects of your theory HDTboy, as Skelstar points out containment of Helium is by far the biggest hurdle to testing.

ZorsT
28th March 2006, 16:55
would it stay in a tubed tyre?

qldzxr250a
28th March 2006, 19:22
they use nitrogen in tyres because it is far more stable then just air and far lees chance of combustion/exploding when the tyres are hot.

as everyone know when air gets hot molecules expand inside the tyre increasing the pressure in the tyre in relation to road/tyre temps.

nitrogen is more stable and less prone to blowouts (has more room for inaccurate tyre pressures)

thats what the tyre shop told me. :rockon:

Warren
28th March 2006, 19:44
I don't think helium will make any difference, as a helium baloon will only hold up at max 1 miniture G.I.Joe. If you really want to reduce the unsprung weight you have to attach a few thousand baloons to the front forks and rear swingarm.

FROSTY
28th March 2006, 19:47
beyeebers reeves--just eat one less mack attack and youll be heaps faster

Motoracer
28th March 2006, 20:12
But... but... what if the bike slips away from you and flys away, into the sky?

cowpoos
28th March 2006, 20:28
Did I hear that Helium will leak out of a rubber tyre wall due it being smaller in particle dimenisions (compared to air that is)?

yes yes yes yes.....bling dispatched.... permiates I think is the word....

skelstar
29th March 2006, 08:22
But does the helium aid in the gyroscopic effect poos? ;)

SixPackBack
29th March 2006, 08:50
But does the helium aid in the gyroscopic effect poos? ;)

Reduction in unsprung weight will reduce gyroscopic effect.

sAsLEX
29th March 2006, 09:10
for all those people still confused over sprun and unsprung weight heres how you tell, sit on yur bike and everthing that moves cloeser to the ground like the muffler, engine you are sprung weight and the things that dont move closer to the ground like the wheels, brakes, forks lowers are unsprung weight.

jonbuoy
29th March 2006, 09:42
Would have more of an effect than helium in your tyres - only on your sprung weight though!

ManDownUnder
29th March 2006, 09:43
Each helium molecule is considerably smaller than anything in the air, and WILL leak from a rubber tire and or rubber tube. It won't be a fast leak - but it'll be consistant.

I'd expect the weight saved to be less than that of adding the tube to contain it too - so there's a negative gain too.

I understand the reason Nitrogen is used it either because it has less moisture in it, and/or because it expands less with heat. Either way it gives a lot more stable tire pressure when they're hot and cold...

Unsprung weight reducton would be best achieved by looking at the densest unsprung parts of the beast. Tires, rims, lower shock and possibly fork oil (although I'd be inclined to stay away from that). Britten did a good job addressing this issue by putting everything in Carbon Fibre.

Strong as hell, and light light light.

If you can come up with a new solution to the problem - go for it, let us know how you get on!
MDU

sAsLEX
29th March 2006, 09:57
this issue by putting everything in Carbon Fibre.

Strong as hell, and light light light.

Wont mention how carconogenic most of the stuff he worked with by hand was......

ManDownUnder
29th March 2006, 10:00
Wont mention how carconogenic most of the stuff he worked with by hand was......

I hear ya - but then there's a lot of things out there that'll kill ya. Besides, it wasn't the material that killed him, it was the lack of safety gear while handling/working it.

There's a lot of people out there working with it, but they have the gear.

svs
29th March 2006, 12:56
Apart from the leakage issue, I reckon by some really rough calculations that you'd save around 50g per tyre.

So is it worth it for 100g reduction in weight - I doubt you'd notice the difference. Start saving for the carbon dymags.

HDTboy
29th March 2006, 12:58
Could do burnouts and save more weight huh?

ManDownUnder
29th March 2006, 13:02
Apart from the leakage issue, I reckon by some really rough calculations that you'd save around 50g per tyre.

So is it worth it for 100g reduction in weight - I doubt you'd notice the difference. Start saving for the carbon dymags.

And has been suggested... take a dump before the race. In fact - down a 1/2 bottle of castor oil... hang around the loos till you're ok to put your clothes back on (let's face it - it IS the decent thing to do), cut down on the maccas and you'll be good.

Unsprung weight - svs has it sussed.
MDU

sAsLEX
29th March 2006, 14:22
Apart from the leakage issue, I reckon by some really rough calculations that you'd save around 50g per tyre.

So is it worth it for 100g reduction in weight - I doubt you'd notice the difference. Start saving for the carbon dymags.

there is a write up in this months superbike where they data log a bike with standard then bst carbon wheels, up to 150mph the carbon wheels have over a hundered metre advantage and they stop quicker as well!

scroter
29th March 2006, 14:33
Can anybody see any obvious problems with filling ones tyres with Helium? Other than the cost

no offence intended, but can you really ride that hard that youll notice the difference. Basically ive never heard of any of the racers talking about that and they still make a bike go pretty darn quick. anyway good luck finding out

sedge
29th March 2006, 15:47
Buy some worn slicks, they'll weigh less due to the lack of rubber... scrape the paint off the wheels, dremel attack the fork lowers and get rid of unwanted castings/sharp edges, use worn brake pads... Ah... Sounds like one of my old bikes already... Heh heh... It wasn't shite, just in a permanent state of reduced unsprung weight.

Sedge.

Ixion
29th March 2006, 16:19
Main things that contribute to unsprung weight are the mass of the brake rotors, the tyres, and the wheel rims.

To reduce the contribution that the weight of the brake rotors make to unsprung weight, they drill holes in them (the rotors - and I know it serves other purposes as well).

So, extend the logic to the other heavy bits, the tyres and wheel rims. Drill holes in them too. That will make them MUCH lighter.

And the best thing is, you can easily do it yourself at home, and it costs nothing. Just get out the electric drill and a decent sized drill bit , and drill away.

DEATH_INC.
31st March 2006, 18:32
Besides, your still not reducing the mass. Sure, filling the tyres with helium will make them lighter in relation to gravity, but will it really have an effect on how quickly the suspension moves in relation to the road and the bike? Someone with an engineering degree might be able to confirm or deny, but in my laymans train of thought, I cant actually see it having any difference what so ever.
This is correct, it may weigh less on the scales, but the force required to move it is still the same......so no advantage whatsoever.

FROSTY
31st March 2006, 19:19
I want some of those super duper light wheels --ferry sexy.

cowpoos
31st March 2006, 19:27
Could do burnouts and save more weight huh?
are u meaning anything by that new sig of yours fella???

it don't make scence??

cowpoos
31st March 2006, 19:31
Main things that contribute to unsprung weight are the mass of the brake rotors, the tyres, and the wheel rims.

To reduce the contribution that the weight of the brake rotors make to unsprung weight, they drill holes in them (the rotors - and I know it serves other purposes as well).

So, extend the logic to the other heavy bits, the tyres and wheel rims. Drill holes in them too. That will make them MUCH lighter.

And the best thing is, you can easily do it yourself at home, and it costs nothing. Just get out the electric drill and a decent sized drill bit , and drill away.
but does a 10inch wheel weighing the same...disc's,bearings,tyres,air included....make the same gyroscopic force as a 17inch wheel??? ponder over it for a while.....

ducatilover
31st March 2006, 21:33
all i know is you can make a huge difference to lap times by using lighter rims, they not only take less force to rotate they also change direction quicker, and they force acting upon it doesnt need to be as great so its easyier to counter-react [brakes i geuss thats what does that other than friction and blah blah] so if it can turn in quicker, accellerate quicker and stop quicker by having lighter rims then why not get them? or why not learn how to ride the bike to its full potential as rossi would? i am a huge fan of weight reduction [and im only 55kg so im not too woried about taking a dump, although it would help cos im fulla shyte]and id rather take weight of my bikes than add power [but doing both is even better]:cool:

Pixie
31st March 2006, 21:41
And has been suggested... take a dump before the race. In fact - down a 1/2 bottle of castor oil... hang around the loos till you're ok to put your clothes back on (let's face it - it IS the decent thing to do), cut down on the maccas and you'll be good.

Unsprung weight - svs has it sussed.
MDU
And use meth for six months.

Really, this forum attracts some pointless discussions