Tyre pressures.

[FROSTY:Me]

Just a lil reminder
Our modern good quality tyres are fantastic at keeping the bike right side up.
But as they get stickier they also leak more air.
Checking tyre pressures regularly is essential to keeping the shiney side up

[Right Charlie]

Hmm, i think ill fill mine up with Nitrogen, bigger molecules stay in longer.

They use it in our Aircraft, just have to be carefull, 180psi Air System i beleive, as oppsed to the 60psi at your garage, it packs a whallop.

[FROSTY:Me]

charlie--you have ready access to nitrogen (he says with his ears perked up)

[k14]

Hmm, i think ill fill mine up with Nitrogen, bigger molecules stay in longer.

They use it in our Aircraft, just have to be carefull, 180psi Air System i beleive, as oppsed to the 60psi at your garage, it packs a whallop.

Huh?? Nitrogen molecules are actually smaller than oxygen (and only by the smallest amount). The atmosphere is made up of over 80% nitrogen anyway so its mostly that in your tyres when you pump them up at the petrol station. AFAIK the reason people use nitrogen to pump up tyres is because it expands less due to heat, so the cold to hot pressures don't vary as much.

[Right Charlie]

Huh?? Nitrogen molecules are actually smaller than oxygen (and only by the smallest amount). The atmosphere is made up of over 80% nitrogen anyway so its mostly that in your tyres when you pump them up at the petrol station. AFAIK the reason people use nitrogen to pump up tyres is because it expands less due to heat, so the cold to hot pressures don't vary as much.

For years, over the road truckers, auto racers and the U.S. military have been filling tires on their vehicles with pure nitrogen. Here's why. In a tire filled with compressed air, the oxygen molecules tend to "migrate" through the wall of the tire over time. That's why, when you open the garage to check on your aunt's dust-covered 1980 Pontiac the tires are often flat. But nitrogen molecules migrate 3 to 4 times more slowly than oxygen, so tires stay properly inflated longer. There are other benefits. Nitrogen retains less heat than oxygen and therefore allows tires to run cooler.

While nitrogen is dry and benign and will not combine chemically with other materials (the metal in tire rims, for instance), compressed air contains trace amounts of water and the oxygen tends to combine with other materials, causing rust and corrosion. If you were to see the inner face (the part enclosing and sealing the inside of the tire) of some fancy aluminum wheels you would be surprised at how corroded they become due to oxidation.

Tour de France bicyclists fill their tires with nitrogen. So do NASCAR, Indy and Formula One racing teams, over-the-road truckers, some fire departments and the U.S. military.

An oxygen molecule is 0.29 nanometers in diameter and a nitrogen molecule is only slightly bigger: 0.31 nanometers

Lord Bless Google

[Right Charlie]

charlie--you have ready access to nitrogen (he says with his ears perked up)

Thats Nitrogen, Pure Nitrogen, not Nitrous Oxide which i suspis you are after

[TwoSeven]

I check mine every day mainly because I notice the difference in a couple of PSI (it depends on how lazy I am whether I actually adjust the pressure or not tho). Over the years I've gotten into the habbit of sticking the pressure guage on - its always close by the bike. Its just part of my pre-ride check I do each day.

On the krappisaki I have leaky valves, so after a week it drops down to 20 or so psi on each tire and I really do have to reinflate them (they are tubed).

[FROSTY:Me]

nope dude--nitrogen for my tyres -keeps em cool -etc etc

[Right Charlie]

nope dude--nitrogen for my tyres -keeps em cool -etc etc

The problem being to inflate them with nitrogen one must first deflate the tire of air.

If the tire becomes unseated i dont have the know how to re-seat it. The nitrogen supply is in the hangar.

[Flyingpony]

I notice the loss of 2psi (or more) so end up inflating every two weeks.
Have a ratio of check typre pressure against fill her up between 2:1 & 4:1.
I'm one of those frequent visitors who rarely tanks, as it appears.

Car tyres get done every month with spare every 2nd.
Air pressure loss on bike is higher than car but then bike travels more km.

[Gremlin]

From my observations I have found that I seem to lose less air if the bike is ridden daily, and if the bike sits for a week it loses more...

Is this actually true??

And boy did I find out the value of air. One ride I went on by myself I hadn't checked the pressure for a week and a bit, and I can only surmise that that was the cause of my handling problems. The ride was very uncomfortable and everything simply felt wrong...

[TwoSeven]

Generally when a tire goes thru a heat cycle it will have lost air when its cooled again. Its unusual to lose much pressure for a tire thats not changed in pressure much (ie. cold) apart from a small amount caused by a leaking valve.

[bugjuice]

I thought tyres run best when they're hot, to make them sticky..?? If they're cool, then surely they'd loose what little heat they would build up..?

[FROSTY:Me]

Different issue entirely BJ --Yea tyres at opperating temp work best but there is also optimum tyre PRESSURE. what using nitrogen does is reduce pressure variations during the heat cycle so the tyres stay at optimum pressure.
Also I notice around a 4-5 psi drop in my race bike tyres between meetings
5 psi over 3 weeks

[Biff]

I run my tyres a few (2-3) PSI below the manufacturers recommended pressure. I find it improves the handling on my bike.