Hey ive heard a lot of stuff about helium filled tires i was wondering if it really made a differance in hopping capabilities.
no but i have heard somthing about magic lobsters…
Mike
If you are suggesting that the helium makes the unicycle lighter, I seriously doubt the tire would hold enough helium to make any significant difference in weight.
Nothing scientific here, just my opinion. Consider this. A toy balloon would probably hold about the same volume of helium as a unicycle tire and that just barely holds up the toy balloon.
EEK
yes but ive heard that the tire getty squishier and more bouncy than normal air.
Helium is a waste of time and stuff. The helium will not stay in the tube for very long, and when the helium really is in the tube it will make as much diference as if you cleaned your uni from dust before you went out for a ride.
But I see much potential in the magic lobsters…
There have been many threads on this, i’m not sure about the dust but certainly scrapping the paint of your frame would save more weight. Using nitrogen would mean that the tyre pressure was affected less by temperature (that’s why it’s used in Formula 1) but because of the change in the properties of the rubber the tyre pressure would need to be changed anyway, so no help there. As fexnix suggested, air tight does not mean sealed for all gases, helium is the second smallest molecule gas, it’s pretty hard to keep it in one place for very long.
I can’t eat lobsteres, magic or otherwise.
You don´t eat them silly…
screw helium… go hydrogen!.. actually… i dont think you could find a difference… you might be able to make the hydrogen blow up… but that would take a ton of skill to get a spark inside your tube…
Not really just run some electirc wires inside the tube. The run a current through it. KBAM… Runs outside to try…
i saw on tv one time it took 75 helium balloons to lift up a chiuaua.
Nitrogen less temperature-sensitive? Doesn’t it follow the law of Boyle - Gay Lussac then?
Hydrogen in your tyre does not explode when a spark is ignited in it. Only if you mix it with oxygen, which would negate the weight issue.
There have been lots of threads about helium in the tyre. The physical effect is very small. As always, the Google search facility is more powerful than this site’s search to find them. I’ve done the (little) work for you:
“The unicycle’s burst into flame! …And…it’s crashing. It’s a tremendous fireball. Oh, this is the worst thing in the world. Oh the humanity!”
Speaking of lifting stuff with balloons:
We saw the new Cirque du Soleil show, Corteo, the other night. Excellent show; one of the best Cirque shows I’ve seen! In one part of the show, a performer comes out in a harness, attached to a bunch of weather-sized balloons. At least eight of them. Her harness allows her to spin around in various directions. After a while, it becomes apparent that her rigging must be pretty sophisticated. Then, the guy tossing her up and down tosses her out over the audience. Members of the audience have to push her back up into the air! At this point it’s obvious there is no rigging attaching her balloons to anything else. She’s really floating, made almost neutrally bouyant by those balloons!
But it’s a lot of balloons, and she’s a very small person, maybe 3’ tall.
Still, I’d love to play with a setup like that…
John - it’s been done - just make sure that you incorporate some kind of altitude control in you plans!
http://www.zipadeeday.com/viewarticle.asp?article=3
Hooked
Not necessarily, they only apply if the gas is of sufficiently low density to say there is no particle interaction (i.e. an Ideal gas)
I’m not sure if pv=nRT can be applied in this situation for that reason, the compressibilty factor Z needs to be taken in to account in the calculation. Now i can’t remeber if Z depends on the gas being used or not, but i think it does because it’s to do with, amongst other things, the size of the molecules and the inter-molecular forces, which are different for each element. To be honest i’m not entirely sure what the answer is, although i am sure we can work it out between us.
Yes, Kris Holm has a throng of magic lobsters and wires at his disposal.
this issue is sort of a joke amongst unicyclists.
It, i believe, came up in a thread about weight of a unicycle.
Z is indeed different for different gases but that’s not the point because it has to do with the P versus V relationship, not su much P versus T. Through some Googling I have found that the main reason that some tyres (e.g. Formula One) are filled with nitrogen is that they run cooler than with air. Therefore, the pressure increase due to riding is also smaller, which is what might have caused your earlier statement. I haven’t been able to find out why nitrogen-filled tyres run cooler. The viscosity of N2 is only marginally lower than that of air.
Teetering on the brink of bad taste, but falling just the right side! I see the giant envelope of the Coker tyre with flames rippling across its surface, and people scattering. I will never proof my inner tube with rocket fuel again.
As for the helium in the tyre thing. It would make a difference, but retaining the helium would be a serious problem. My step father told me a tale of a friend who wanted to make a model hydrogen balloon. He set up the chemical reacction (what is it? Limestone in hydrochloric acid?) and a system of tubes to direct the hydrogen into the er… polythene envelope. Went out for a couple of hours, came back in, saw that the envelope was still disappointingly flat and was only just stopped from turning the light on to have a closer look.
The weight of the uni is more important than the weight of the rider, and the weight of the wheel (especially the tyre/tube/rim) is more important than the weight of the frame or seat. However, I suggest anyone really wanting to make significant savings would be better advised to drill the rim - or buy a Sheldon Brown monospoke hubset.
I first thought you said thong, realy bad mental image