MotoGP 2015

[Grumph]

...tyres, but if you want to cross over to that side...I ride as much as before but my destination is not as far as it was some years back and sometimes I fall off before I get there...

Hahaha.

I ride mine as much as often, but occasionally have had too much to drink and fail to ride it all the way home.

Next time i see you both at a race meeting i must introduce you....talk about dad 'n dave....

[J.A.W.]

Next time i see you both at a race meeting i must introduce you....talk about dad 'n dave....

Translation for those who aint greybeards.. D & D = Dumb & Dumber..

[Ruahine]

Different gasses are different 'weights'. That 'weight' dictates how it reacts to temp and pressure.

To say they all do the same thing at certain temp is fucken retarded.

He is right though. Avogrado's law states that 1 mole of any gas at the same temperature and volume will exert the same pressure. The atomic weight has no relevance.

[Ruahine]

You are correct but you need to account for the different mass.
Pressure
_______________ = constant
Temperature

Thus For a fixed mass of gas, at a constant volume, the pressure (p) is directly proportional to the absolute temperature (T)."
But you need to remember not all gasses have equal mass.Thus not all gases respond to heat the same for a given pressure.


In fairness 80% of the air is nitrogen anyway.
But if the other bikes were using Nitrogen, Danni could have used Simple compressed air.


Gas Molecular weight

Helium 4.02
Nitrogen 28.02
Air 29
CO2 44.01

As Shaun said HRC know all this or have people that do.

Its not the atomic mass that but the number of molecules (moles) which relates to pressure. In theory a mole of oxygen gas will exert the same pressure as a mole of nitrogen gas provided they are in the same volume and at the same temperature.


My understanding of the use of pure nitrogen is that it is dry. Using compressed air may introduce water into the tyre which will affect the pressure/temperature relationship. The introduction of water into tyres is also an issue for aircraft which cruise at high altitude as it can freeze. Nitrogen also has the advantage of being a larger molecule so is less able to escape from the tyre compound than oxygen.

[Shaun Harris]

Its not the atomic mass that but the number of molecules which relates to pressure.


My understanding of the use of Nitrogen is that it is dry. Using compressed air may introduce water into the tyre which will affect the pressure/temperature relationship. The introduction of water into tyres is also an issue for aircraft which cruise at high altitude as it can freeze. Nitrogen also has the advantage of being a larger molecule so is less able to escape from the tyre compound than oxygen.

This I agree and understand. What I do not understand is, if the facts mentioned by others and you are correct, why do the top class world bike race teams not use Nitrogen all the time? There is some thing being missed by all of us obviously.

[husaberg]

Its not the atomic mass that but the number of molecules (moles) which relates to pressure. In theory a mole of oxygen gas will exert the same pressure as a mole of nitrogen gas provided they are in the same volume and at the same temperature.


My understanding of the use of pure nitrogen is that it is dry. Using compressed air may introduce water into the tyre which will affect the pressure/temperature relationship. The introduction of water into tyres is also an issue for aircraft which cruise at high altitude as it can freeze. Nitrogen also has the advantage of being a larger molecule so is less able to escape from the tyre compound than oxygen.

Molecular mass or molecular weight refers to the mass of a molecule. It is calculated as the sum of the mass of each constituent atom multiplied by the number of atoms of that element in the molecular formula.

All the bottom stuff is also true, plus Nitrogen gas is inert. it removes a variability, but like I said this thread isn't a place for this stuff.

The original point discussed was pedro and tyre pressure. Why he would feel he had to have less than 25 psi or that he was hard done by compared to the others.

[Grumph]

This I agree and understand. What I do not understand is, if the facts mentioned by others and you are correct, why do the top class world bike race teams not use Nitrogen all the time? There is some thing being missed by all of us obviously.

Could it be rider preference ? Some may be able to live with low pressures early on better than others who may want a rapid pressure rise. If the end temp is the same it would only be the period of temp and pressure rise where there'd be a noticeable difference.

[Ruahine]

This I agree and understand. What I do not understand is, if the facts mentioned by others and you are correct, why do the top class world bike race teams not use Nitrogen all the time? There is some thing being missed by all of us obviously.

What else do they use? I am no expert but in terms of temperature vs pressure there is no inherent advantage to nitrogen (other than it being cheap and inert) over any other gas so I suspect that compressed air with the moisture removed would be as good at maintaining predictable tyre pressures?

[Shaun Harris]

What else do they use? I am no expert but in terms of temperature vs pressure there is no inherent advantage to nitrogen (other than it being cheap and inert) over any other gas so I suspect that compressed air with the moisture removed would be as good at maintaining predictable tyre pressures?

Compressed Air mate.

[Autech]

Next time i see you both at a race meeting i must introduce you....talk about dad 'n dave....

Haha, look forward to it!

So forward racing are off to WSBK to work with MV, with Marco Melandri as their test rider. Hasn't he already tried to develop a bike recently?


Sent from my iPhone using Tapatalk

[BMWST?]

You are correct but you need to account for the different mass.
Pressure
_______________ = constant
Temperature

Thus For a fixed mass of gas, at a constant volume, the pressure (p) is directly proportional to the absolute temperature (T)."
But you need to remember not all gasses have equal mass.Thus not all gases respond to heat the same for a given pressure.


In fairness 80% of the air is nitrogen anyway.
But if the other bikes were using Nitrogen, Danni could have used Simple compressed air.


Gas Molecular weight

Helium 4.02
Nitrogen 28.02
Air 29
CO2 44.01

As Shaun said HRC know all this or have people that do.

By air you mean oxygen.All that shit mixed together is AIR.

[husaberg]

By air you mean oxygen.All that shit mixed together is AIR.

By air I meant atmospheric air, Funny enough its actually mostly Nitrogen with some oxygen plus some other stuff, maybe you have less where you are?

[BMWST?]

Molecular mass or molecular weight refers to the mass of a molecule. It is calculated as the sum of the mass of each constituent atom multiplied by the number of atoms of that element in the molecular formula.

All the bottom stuff is also true, plus Nitrogen gas is inert. it removes a variability, but like I said this thread isn't a place for this stuff.

The original point discussed was pedro and tyre pressure. Why he would feel he had to have less than 25 psi or that he was hard done by compared to the others.

we have already discussed this.Pedro is so light he can run lower pressures and acheive the same tyre heating as the others.The minimum pressure is too hard for him.(at PI anyway,)

[Moise]

...mine lasts twice as long if I only ride half of the time that I should...

The rear was almost worn out a couple of months ago but the weather has been shit lately so it may last until the holidays.

[Moise]

What else do they use? I am no expert but in terms of temperature vs pressure there is no inherent advantage to nitrogen (other than it being cheap and inert) over any other gas so I suspect that compressed air with the moisture removed would be as good at maintaining predictable tyre pressures?

Exactly. The issue is producing dry air but it's not that difficult.

I'd use nitrogen if cost isn't an issue.