the world's craziest idea

[Nicf]

what would happen if you filled a unicycle with helium like the tire and frame I have a friend that was looking into buying a bike that was filled with helium and was really lite but does the helium realy make it lighter?? or is it just the carbon frame ? this bike is lighter that light and I like the concept like what if you could make a unicycle that is extremely lite would this really work???

This is really my friend asking but still seams like a good idea.
whynot?
try this link
hope I don't sound crazies

[Klaas Bil]

What are you filling with helium?

The frame? If it's gas-tight anyway, you'd better suck it vacuum.

The tyre? Would make a unicycle one or a few grams lighter (compared to air-fill) depending on the tyre size. However, regular tyres don't hold helium for a long time.

Conclusion: impractical idea.

[adjuggler]

Originally Posted by Klaas Bil

What are you filling with helium?

The frame? If it's gas-tight anyway, you'd better suck it vacuum.

The tyre? Would make a unicycle one or a few grams lighter (compared to air-fill) depending on the tyre size. However, regular tyres don't hold helium for a long time.

Conclusion: impractical idea.

+1

Even if you could spend all that extra cash to seal and use parts to hold the helium, it would not be worth the weight reduction to fill it with helium. It would be as rediculus as filling it with... well, puppies.

[oneisenough]

I've heard of this idea before, I think it was in BMX, but i don't remember any of the details, as I was in like 4th grade and thought that all the pros used it I don't remember if someone actually tried this, or if it was like this, just a theory

[Joseppi]

Helium is lighter than air because it is less dense. Ergo, to fill a tire properly with helium, you would need more helium than you would need normal air in order to get enough pressure in the tire. In the end, you wouldn't really lose any weight at all.

[hobo_chuck]

Originally Posted by Joseppi

Helium is lighter than air because it is less dense. Ergo, to fill a tire properly with helium, you would need more helium than you would need normal air in order to get enough pressure in the tire. In the end, you wouldn't really lose any weight at all.

nah, it's still less dense under the pressure of the atmosphere, under the pressure of a balloon, etc.
Why not tire pressure? Though you would probably only save a few grams.....

Originally Posted by Klaas Bil

What are you filling with helium?

The frame? If it's gas-tight anyway, you'd better suck it vacuum.

+1

[Emile.m]

Originally Posted by Klaas Bil

The frame? If it's gas-tight anyway, you'd better suck it vacuum.

If there's no air, no gaz, no nothing inside the frame, it would crush because of the atmospheric pressure.

[hobo_chuck]

Originally Posted by Emile.m

If there's no air, no gaz, no nothing inside the frame, it would crush because of the atmospheric pressure.

It would certainly dent/bend more easily.
But why is that an issue on a road bike?
It's not like this is being considered for a trials..and even then you could find a good compromise. It's not like frames bend inwards before they simply break at the weld.

[Spudman]

Air weighs about 0.075 lbs per cubic foot at standard atmospheric pressure. If you have some huge trials frame made of 1" tubing, we can estimate the volume to be somewhere around 30 cubic inches (way bigger than it really is). If you pull a vacuum in said frame you'll be able to save a whopping 0.001 lbs, or about half a gram!

[tim_desmet]

lol, it wouldn't make your unicycle a lot lighter, and I think it's expensif to fill your tire,... with helium
But you can try it

[hobo_chuck]

Originally Posted by Spudman

Air weighs about 0.075 lbs per cubic foot at standard atmospheric pressure. If you have some huge trials frame made of 1" tubing, we can estimate the volume to be somewhere around 30 cubic inches (way bigger than it really is). If you pull a vacuum in said frame you'll be able to save a whopping 0.001 lbs, or about half a gram!

yup. but you have to consider the seatpost, which isn't practical to have a vacuum in at all, so with 22" of 1" tubing (the sides on a trials frame) I would estimate the volume at 69.1150384 cubic inches, actually.
I dunno where you got 30, so double your calculations
double again for a 36er
and again for the Coker V2
nothing for the nimbus(no air)

[catinabag1]

even if the uni is lighter, it still has the same mass. it would still be just as hard to move around.

[hobo_chuck]

Originally Posted by catinabag1

even if the uni is lighter, it still has the same mass. it would still be just as hard to move around.

air has mass
more so then helium and umm.....a very large number of times that of a vacuum.(you'll never get a perfect vacuum, sorry.)

[Spudman]

Originally Posted by hobo_chuck

yup. but you have to consider the seatpost, which isn't practical to have a vacuum in at all, so with 22" of 1" tubing (the sides on a trials frame) I would estimate the volume at 69.1150384 cubic inches, actually.
I dunno where you got 30, so double your calculations
double again for a 36er
and again for the Coker V2
nothing for the nimbus(no air)

I gave it 40" of 1" tubing (includes the seatpost)

40*(pi*0.5^2) = 31.4 cubic inches.

[hobo_chuck]

Originally Posted by Spudman

I gave it 40" of 1" tubing (includes the seatpost)

40*(pi*0.5^2) = 31.4 cubic inches.

sorry, I squared the diameter
my bad.
You're still off though, in the same direction I was.
How do you square a half again?
(ok, the seatpost COULD potentially be two feet long....but no vacuum there by any reckoning of mine)